NKF KDOQI GUIDELINES 2000
GUIDELINES FOR ANEMIA OF CHRONIC KIDNEY DISEASE
III. Iron Support
Iron is essential for hemoglobin formation, as is erythropoietin. Several important issues related to iron deficiency and its management in the CKD patient, particularly in patients receiving Epoetin therapy should be considered:
1. Iron (blood) losses are high, particularly in the hemodialysis patient.
2. Oral iron usually cannot maintain adequate iron stores, particularly in the hemodialysis patient treated with Epoetin.
3. Epoetin, by stimulating erythropoiesis to greater than normal levels, often leads to functional iron deficiency.
4. Prevention of functional (and absolute) iron deficiency by regular use of intravenous iron (ie, small doses, weekly, to replace predicted blood losses) improves erythropoiesis.
5. The serum iron, total iron binding capacity, and serum ferritin are the best indicators of iron available for erythropoiesis and iron stores, but they do not provide absolute criteria for either iron deficiency or iron overload.
These guidelines suggest that the regular use of small doses of IV iron, particularly in the hemodialysis patient, will prevent iron deficiency and promote better erythropoiesis than can oral iron therapy.
6. Prior to July 1999, the only IV iron preparation available in the United States was iron dextran. The doses recommended for iron dextran are detailed in these Guidelines. Since July 1999, iron gluconate and iron sucrose have become available for IV use in the United States. Since the amount of iron gluconate per vial differs from that of iron dextran, the Work Group recommends that the substitution of iron gluconate for iron dextran would be 8 doses of 125 mg of iron gluconate (over 8 weeks per quarter), or 8 doses of 62.5 mg of iron gluconate over 8 weeks instead of 10 doses of 50 mg of iron dextran over 10 weeks. Doses of iron gluconate larger than 125 mg given at one time are not recommended by the manufacturer, whereas iron dextran can be given at one time at doses of 250, 500, and/or 1,000 mg doses, if indicated. Iron sucrose can be given in doses of 100 mg or less.
Assessment of Iron Status
Iron status should be monitored by the percent transferrin saturation (TSAT) and the serum ferritin. (Evidence)
Target Iron Level
A. CKD patients should have sufficient iron to achieve and maintain an Hgb/Hct of 11 to 12 g/dL/33% to 36%. (Evidence)
B. To achieve and maintain this target Hgb/Hct, sufficient iron should be administered to maintain a TSAT of >20%, and a serum ferritin level of >100 ng/mL (Evidence).
C. In hemodialysis patients in whom TSAT is >20% and the serum ferritin is >100 ng/mL, yet the Hgb/Hct is 11 g/dL/<33%, as well as in patients requiring comparatively large doses of Epoetin to maintain an Hgb/Hct of 11 to 12 g/dL/33% to 36%, the patients response to 1.0 g of IV iron given over 8 to 10 weeks should be observed. (Opinion) If in response to this course of iron, there is no increase in Hgb/Hct and no increase in serum ferritin and TSAT level, at the same dose of Epoetin, a second course of IV iron should be tried. (Opinion) If, in response to this second course of IV iron, there still is no increase in Hgb/Hct, but either the TSAT or serum ferritin level increases, then the weekly dose of IV iron should be reduced to the lowest amount required to maintain the TSAT >20% and serum ferritin at >100 ng/mL. (Opinion) If, on the other hand, in response to either of these courses of IV iron, there is an increase in Hgb/Hct at a constant dose of Epoetin, or a stable Hct at a decreased dose of Epoetin, then it is reasonable to administer 1.0 g of iron IV over 8 to 10 weeks again in an effort to achieve and maintain the Hgb/Hct at 11 to 12 g/dL/33% to 36%. (Opinion)
D. CKD patients are unlikely to respond with a further increase in Hgb/Hct and/or a further reduction in Epoetin dose required to maintain a given Hgb/Hct if the TSAT increases to >50% and/or the serum ferritin level increases to >800 ng/mL. (Evidence)
Monitoring Iron Status
A. During the initiation of Epoetin therapy and while increasing the Epoetin dose in order to achieve an increase in Hgb/Hct, the TSAT and the serum ferritin should be checked every month in patients not receiving intravenous iron, and at least once every 3 months in patients receiving intravenous iron, until target Hgb/Hct is reached. (Opinion)
B. Following attainment of the target Hgb/Hct, TSAT and serum ferritin should be determined at least once every 3 months. (Opinion)
C. Intravenous iron therapy, if given in amounts of 100 to 125 mg or less per week, does not need to be interrupted in order to obtain accurate measurements of iron parameters. (Evidence)
D. If individual doses of intravenous iron are 1,000 mg or larger, an interval of 2 weeks should occur before accurate assessment of serum iron parameters can be determined (Evidence). Accurate assessment of iron parameters after intravenous infusion of 200 to 500 mg of iron may require an interval of 7 or more days (Opinion).
E. In CKD patients not treated with Epoetin and whose TSAT is >20% and serum ferritin is >100 ng/mL, the iron status should be monitored every 3 to 6 months. (Opinion)
Administration of Supplemental Iron
A. Supplemental iron should be administered to prevent iron deficiency and to maintain adequate iron stores so that CKD patients can achieve and maintain an Hgb 11 to 12 g/dL (Hct 33% to 36%) in conjunction with Epoetin therapy. (Evidence)
B. If oral iron is given, it should be administered at a daily dose of at least 200 mg of elemental iron for adults and 2 to 3 mg/kg for pediatric patients. (Evidence)
C. The adult CKD, home hemodialysis, and peritoneal dialysis (PD) patient may not be able to maintain adequate iron status with oral iron. (Evidence) Therefore, 500 to 1,000 mg of iron dextran may be administered IV in a single infusion, and repeated as needed, after an initial one-time test dose of 25 mg. As of January 2000, it is not recommended to give these large doses of iron gluconate as a single infusion. (Opinion)
D. A trial of oral iron is acceptable in the hemodialysis patient (Opinion), but is unlikely to maintain the TSAT >20%, serum ferritin >100 ng/mL, and Hgb/Hct at 33% to 36%/11 to 12 g/dL. (Evidence)
E. To achieve and maintain an Hgb 11 to 12 g/dL (Hct of 33% to 36%), most hemodialysis patients will require intravenous iron on a regular basis. (Evidence)
F. Intravenous iron can be given on a variety of dosage schedules. If the TSAT is <20% and/or the serum ferritin is <100 ng/mL, the Anemia Work Group recommends that, in adults, 100 to 125 mg of iron be administered IV at every hemodialysis for 10 to 8 doses, respectively. (Opinion) If the TSAT remains <20% and/or the serum ferritin <100 ng/mL, another course of IV iron (100 to 125 mg per week for 10 to 8 weeks) is recommended. Once the patients TSAT is >20% and the serum ferritin is >100 ng/mL, the Anemia Work Group recommends that 25 to 125 mg of iron be given IV once per week (see Guideline 6: Target Iron Level). (Opinion) Schedules for IV iron administration ranging from three times per week to once every 2 weeks are also reasonable in order to provide 250 to 1,000 mg of iron within 12 weeks. (Opinion)
G. Most patients will achieve an Hgb 11 to 12g/dL (Hct of 33% to 36%) with TSAT and serum ferritin levels <50% and <800 ng/mL, respectively. (Evidence) In patients in whom TSAT is >50% and/or serum ferritin is >800 ng/mL, IV iron should be withheld for up to 3 months, at which time the iron parameters should be re-measured before IV iron is resumed. (Opinion) When the TSAT and serum ferritin have fallen to ñ50% and ñ800 ng/mL, IV iron can be resumed weekly at a dose reduced by one third to one half. (Opinion)
H. It is anticipated that once optimal Hgb/Hct and iron stores are achieved, the required maintenance dose of IV iron may vary from 25 to 125 mg/week for hemodialysis patients. The goal is to provide a weekly dose of IV iron in hemodialysis patients that will allow the patient to maintain the target Hgb/Hct at a safe and stable iron level. The maintenance iron status should be monitored by measuring the TSAT and serum ferritin no less than every 3 months. (Opinion)
I. Oral iron is not indicated for the CKD patient who requires maintenance doses of IV iron. (Opinion)
RATIONALE FOR GUIDELINES 5-8
Effective erythropoiesis requires both iron and erythropoietin. When CKD patients lack an adequate supply of either one or both, anemia results. Among United States ESRD patients receiving Epoetin, more than 50% are iron deficient, which probably accounts, at least in part, for why the mean Hct among ESRD patients in the United States in 1993 was 30.2%, with 43% having a Hct <30% (Endnote f).66 To remedy this problem, clinicians will need to address three important issues regarding management of iron in CKD patients:
1. Under what circumstances should a patient receive supplemental iron?
2. How much iron should they receive?
3. How (by what route and according to what dosing schedule) should they receive it?
The Iron Support section of these guidelines (Guidelines 5-10) addresses how to ensure that patients have sufficient iron to achieve and maintain a target Hgb 11 to 12 g/dL (Hct of 33% to 36%). The Administration of Epoetin section (Guidelines 11-19) addresses how to ensure that patients receive sufficient Epoetin to achieve and maintain a target Hgb 11 to 12 g/dL (Hct of 33% to 36%).
In formulating its recommendations regarding these issues, the Anemia Work Group focused on the following:
1. The iron needs and the importance of maintaining adequate iron status in CKD patients
2. Assessment of iron status: the sensitivity and specificity of the TSAT and serum ferritin in detecting absolute and functional iron deficiency, as well as iron overload
3. An analysis of the effectiveness of oral versus IV iron
4. Administration of IV iron, and its potential associated risks
5. Iron overload
Iron Needs in CKD Patients
Iron deficiency is common in CKD, particularly in hemodialysis patients, for several reasons, including substantial losses of blood from frequent blood tests, blood remaining in the dialysis tubing and dialyzer, and gastrointestinal blood losses, that cannot be compensated for by sufficient absorption of iron from the gastrointestinal tract. Epoetin therapy increases the rate of erythropoiesis and therefore the demand for iron, which, when coupled with substantial blood losses, compounds the difficulty of maintaining adequate iron stores in hemodialysis patients.
Normal body iron stores are 800 to 1,200 mg.132 If the initial Hct is 25% and the target Hct is 35%, the magnitude of supplemental iron required by patients during the first 3 months of Epoetin therapy is approximately 1,000 mg. Of this, approximately 400 mg of iron are needed simply to replace iron losses during 3 months of hemodialysis (Endnote g). The other 600 mg of iron are needed to support production of sufficient numbers of red blood cells to achieve the target Hgb/Hct (Endnote h). Once the target Hgb/Hct is achieved, approximately 400 to 500 mg of supplemental iron will be needed every 3 months to replace iron losses and maintain adequate iron stores.
In children, mean daily intestinal blood losses (pre-dialysis) are 6 mL/m2 BSA. For pediatric hemodialysis patients, mean daily GI blood losses increase to 11 mL/m2, and dialysis-associated blood losses are 8 mL/m2 per treatment. Cumulative annual iron losses therefore approximate 1.6 g/1.73 m2 in pediatric hemodialysis patients, and 0.9 gm/1.73 m2 in predialysis pediatric patients and probably in those on PD.133 Although there are no data on the calculated iron needs in pediatric patients on dialysis, the rationale for iron supplementation is similar to that described for adults.
Assessment of Iron Status
An ideal test of a CKD patients iron status would accurately indicate whether the patient has:
1. Sufficient amount of iron available to support achievement and maintenance of an Hgb 11 to 12 g/dL (Hct of 33% to 36%); and
2. An excessive amount of body iron.
Unfortunately, no test exists which accomplishes either of these goals and which is practical to administer (Endnote i).
Currently, the two best tests of iron status are the percent TSAT and the serum ferritin. The percent TSAT (serum iron multiplied by 100 and divided by total iron binding capacity [TIBC]) reflects iron that is readily available for erythropoiesis. The TIBC essentially measures circulating transferrin. The transferrin molecule contains two binding sites for transporting iron from iron storage sites to erythroid progenitor cells. A TSAT of 50% indicates that half of the binding sites are occupied by iron. Normally there is a diurnal variation in the level of serum iron and, thus, the TSAT. Since blood for these tests is generally obtained at the same time of day in relation to either clinic or dialysis visits, serial measurements of TSAT typically are not affected by this diurnal variation.
The distinction between absolute and functional iron deficiency is crucial to understanding what constitutes adequate TSAT and serum ferritin levels in Epoetin-treated patients. In otherwise healthy subjects, iron deficiency is considered "absolute" when iron stores are depleted, as indicated by serum ferritin levels <12 ng/mL,54 and iron delivery to the erythroid marrow is impaired, as evidenced by TSAT levels below 16%.53 Absolute iron deficiency in CKD patients has been defined as serum ferritin levels <100 ng/mL and TSAT levels <20%. In contrast to absolute iron deficiency, functional iron deficiency results when there is a need for a greater amount of iron to support hemoglobin synthesis than can be released from iron stores (reticuloendothelial cells). This situation, which can be caused by pharmacological stimulation of erythropoiesis by Epoetin, can occur in the presence of adequate iron stores. As a result, the percent TSAT decreases to levels consistent with iron deficiency despite a normal or elevated serum ferritin.35,134-136 Patients with this condition do not meet traditional laboratory criteria for absolute iron deficiency, but may demonstrate an increase in Hgb/Hct when IV iron is administered.
A common clinical problem is distinguishing between functional iron deficiency and an inflammatory iron block, since the TSAT may be <20% and serum ferritin may be 100 to 700 ng/mL in both situations (although the serum ferritin can be even higher in the presence of inflammation). In the former condition, serial levels of serum ferritin decrease during Epoetin therapy, yet remain elevated (>100 ng/mL); in contrast, in the latter condition, there is usually an abrupt increase in serum ferritin associated with a sudden drop in the TSAT. If it is not clear which of these conditions exists, it is recommended that weekly IV iron (50 to 125 mg) be given for up to 8 to 10 doses. If no erythropoietic response occurs, an inflammatory block is most likely, and no further IV iron should be given until the inflammatory condition has resolved.
Transferrin Saturation Traditionally, a TSAT of <20% in hemodialysis patients has been considered to be indicative of iron deficiency. However, several studies52,137-143 have demonstrated that a TSAT of <20% versus >20% is not an accurate discriminator between patients who are or are not iron deficient. Although the vast majority of patients who have a TSAT <20% are iron deficient, there are some patients who have a TSAT <20% who are able to achieve a Hct of 33% to 36% and/or do not respond to higher doses of iron (and TSAT levels) with either an increase in Hct or maintenance of Hct with a reduced dose of Epoetin. However, there also are many patients who have a TSAT >20% who are functionally iron deficient (ie, they respond to higher doses of iron, and a corresponding increase in their TSAT, with either an increase in their Hct or maintenance of their Hct at a reduced dose of Epoetin)52,137-143 (Endnote j).
Ferritin Whereas TSAT reflects iron that is readily available for erythropoiesis, serum ferritin reflects storage iron, ie, iron that is stored in liver, spleen, and bone marrow reticuloendothelial cells. As is the case with the TSAT, the serum ferritin level is most accurate as a predictor of iron deficiency or iron overload when it is extremely low or extremely high, respectively.
Just as serum ferritin is not perfectly sensitive, it also is not perfectly specific. In part, this is due to the fact that, in addition to reflecting body iron stores, serum ferritin also is an acute phase reactant. As such, it can increase in the setting of either acute or chronic inflammation.
While no single value of TSAT or serum ferritin accurately discriminates between CKD patients who are or are not functionally iron deficient, available data demonstrate that the lower the TSAT and the serum ferritin, the higher the likelihood that a patient is iron deficient, and the higher the TSAT and the serum ferritin, the lower the likelihood that a patient is iron deficient.139-146
Other tests of iron status, such as zinc protoporphyrin or RBC ferritin, are less widely available and appear to offer no increase in diagnostic sensitivity or specificity over serum ferritin and TSAT.147 The percent of hypochromic red blood cells does appear to be a sensitive and reliable indicator for iron deficiency and has been shown to be helpful in the diagnosis of functional iron deficiency.55,56 Normally, there are less than 2.5% of red blood cells with individual cell hemoglobin levels of less than 28 g/dL. Values exceeding 10% are compatible with iron deficiency in the Epoetin-treated patient. This measurement is presently performed as part of a routine full blood count sample that requires a Technicon H-1, H-2, or H-3 automated cell counter, which is specialized equipment (Bayer Diagnostics) available in parts of Europe, but is presently not available in most medical centers in the United States.
Several recommendations of a European Erythropoietin Symposium regarding iron supplementation (whether oral or IV) during Epoetin therapy were as follows:
1. Serum ferritin should be maintained at greater than 100 ng/mL. No upper limit was set.
2. Transferrin saturation should be maintained at greater than 20%. Hypochromic red blood cells should be maintained at less than 10%. Iron status should be evaluated monthly initially, then every 2 to 3 months.148
Use of Oral Versus Intravenous Iron
Inadequacy of Oral Iron in Hemodialysis Patients A number
of studies have documented the failure of oral iron supplements to maintain
adequate iron stores in Epoetin-treated hemodialysis patients52,134,135,139,141,149-153
(Table IV-2). Even though there may be temporary improvement
in the Hct with oral iron therapy, blood (iron) losses exceed the absorption
of iron from oral supplements in most Epoetin-treated hemodialysis patients
and ultimately iron stores decrease (as indicated by decreasing serum ferritin
levels; Table IV-2). Eventually, as negative iron balance
continues, iron stores decrease and will become inadequate.
Table IV-2. Effects of Oral Iron Therapy in Hemodialysis Patients
|Study||No. of Patients||Elemental Iron/Day||Duration (mo)||Hgb/Hct||%TSAT||Ferritin||Epoetin Dose|
|Kooistra et al151||19||105||10||22.8-32.8||25-24||447-265||75 U/Kg/wk|
|Dunea et al152||73||260||12||2-4,000 U/HD|
|Bergmann et al149||7||227||5||22.0-29.0||NA||400-100||360 U/kg/wk|
|Macdougall et al 141||13||120||4||7.2-10.0||27-31||309-100||75 U/kg/wk|
|Wingard et al150||46||200||6||26.3-29.7||20-211||151-106||0,660 U/HD|
|Anastassiades et al153||38||300||3||6.9-10.4||29-27||211-92||110 U/kg/wk|
|Fishbane et al139||32||195||4||31.8-31.8||21-20||179-157||7563 U/HD|
|Horl et al135||12||40-80||3||22.5-33.0||NA||1,145-251||150 U/Kg/wk|
Although there is no evidence to suggest that gastrointestinal iron absorption is impaired in patients with kidney failure,154-156 even in non-CKD individuals only a small fraction of oral iron is absorbed. Consequently, 200 mg of elemental iron ingested daily usually cannot meet the demands of Epoetin-induced increase in erythropoiesis and hemodialysis-associated blood losses. Moreover, since oral iron absorption is inversely correlated with body iron stores, it is unlikely that even a greater amount of oral iron would be absorbed when the serum ferritin level exceeds approximately 200 ng/mL155,157 or the transferrin saturation exceeds 20%158 levels that are needed for optimal erythropoiesis. On the other hand, iron absorption also correlates with the degree of erythropoiesis, and can be increased during Epoetin therapy.159,160 However, in the latter study involving normal subjects,160 enhanced erythropoiesis was achieved with amounts of Epoetin greater than those generally given to patients with CKD.
Inadequate absorption of oral iron is exacerbated by the fact that patient compliance with oral iron regimens is often poor due to one or more of the following: the inconvenience of dosing (1 hour pre-prandial or 2 hours post-prandial administration for optimal absorption); side effects, including gastric irritation and constipation; and out-of-pocket cost.
Although most Epoetin-treated hemodialysis patients will require intravenous iron to maintain iron stores, a small percentage of hemodialysis patients, as well as many peritoneal dialysis and CKD patients, are able to maintain adequate iron stores using only oral iron supplements, perhaps as a result of augmented intestinal iron absorption,160 smaller blood losses, and/or lower Epoetin requirements.52,140
IV Iron Intravenous iron has been shown to improve responsiveness to Epoetin in selected patients with CKD and PD patients52,140,161 and may reduce the amount of Epoetin needed (if used) to achieve and maintain a target Hgb/Hct. In addition, frequent administration of low doses of IV iron improves the Hgb/Hct and can reduce Epoetin requirements in hemodialysis patients (Table IV-3)139-142,144-146,162 (Endnote k). In addition, several studies have shown that even without the use of Epoetin, the Hgb/Hct can increase in a significant number of patients treated with frequent doses of IV iron, but not always to the target level52,134,140 (Table IV-3). Several studies have shown the superiority of IV iron therapy by comparing it to oral iron therapy and showing that IV iron therapy either increases the Hgb/Hct and/or reduces Epoetin requirements.139,141,163 In the 8 studies, reported by 7 authors, in which iron stores were thought to be normal based upon a serum ferritin of >100 ng/mL (in 5 of these studies, the baseline TSAT values were 23% to 31%), the response to a prorated weekly dose of IV iron ranging from 30 to 200 mg resulted in an increase in Hgb/Hct of 19% ± 20% and a reduction in Epoetin requirements of 34% ± 27%.139-142,144,146,161,162 Other studies have shown the erythropoietic benefit of increasing the TSAT to >20% and serum ferritin to >100 ng/mL, respectively.138,143
Table IV-3. Effects of Intravenous Iron Therapy in Hemodialysis Patients
|No. of Patients||IV Iron (mg/wk)||Duration (mo)||
Effect in Iron Deficiency
|Sunder-Plassmann and Horl145||52||100||6||9.4-11.1||13-24||52-534||+18%||-17%|
|Taylor et al144||12||31||6||10.1-11.0||NA||68-211||+09||-33%|
|Sepandj et al146||50||50||6||8.8-10.0||NA||36-217||+14%||-34%|
|Effect with "Normal" Iron Stores|
|Silverberg et al140||41||50||6||28.7-33.7||27-31||99-403||+17%||0|
|Senger and Weiss162||13||25-50||12||32.6-34.7||14-36||111-609||+06||-75%|
|Taylor et al144||34||31||6||9.9-11.3||NA||176-305||+14||-33%|
|Fishbane et al139||20||200||4||32.5-34.4||23-75||191-754||+12||-46%|
|Granolleras et al142||18||30||4||29.0-31.0||31-33||321-654||+07||-30%|
|Silverberg et al140||41||50||6||33.7-33.6||31-29||403-383||0||-61%|
|Macdougall et al141||12||125||4||7.3-11.9||26-23||345-350||+63||0|
|Suh and Wadhwa161||7*||100||7||29.0-38.0||18-35||267-660||+31||-27%|
|Effect without Epoetin|
|Allegra et al134||11||93||6||7.0-8.0||NA||60-500||5/11 pts responded|
|7 93||6||7.0-7.0||NA||700-900||0/7 pts responded|
|Silverberg et al140||5*||50||6||27.7-35.6||24-36||145-460||+17%|
|Silverberg et al52||33||50||5||29.6-31.5||22-27||106-297||66%|
|* CAPD patients.|
| CKD patients.|
IV Iron Protocol
The protocol that the Anemia Work Group recommends for administering IV iron dextran or iron gluconate in adult hemodialysis patients with absolute iron deficiency is 100 mg of iron dextran or 125 mg of iron gluconate during each dialysis for 10 or 8 doses respectively. For maintenance iron therapy, and treatment and prevention of functional iron deficiency, the recommendation is 25 to 100 mg of IV iron dextran every week for 10 weeks, or 31.25 to 125 mg of iron gluconate every week for 8 weeks, with measurement of the TSAT and serum ferritin no sooner than 2 to 7 days after the last dose, depending on the magnitude of the above doses. Doses of 100 to 125 mg require 7 days to elapse for accurate monitoring.164-168 Measurement of transferrin saturation and serum ferritin may be inaccurate if they are performed within 14 days of receiving a single dose of 1 gram or more of iron intravenously.143,168,169
The frequency of maintenance IV iron therapy can be thrice weekly (with every hemodialysis),142 twice weekly,139,144 weekly,140,145,161,162 or every other week,141 but should provide 250 to 1,000 mg of iron within 12 weeks. Iron status during the maintenance phase of Epoetin treatment should be monitored by measuring the TSAT and serum ferritin every 3 months.
Dosing of IV iron in pediatric patients should be adjusted to weight. The regimen employed successfully for a 10-dose course of IV iron in one study for pediatric hemodialysis patients is shown in Table IV-4.170 The dosing recommendations for pediatric CKD and PD patients are shown in Table IV-5.
Table IV-4. Iron Dextran Dosing Recommendations for Pediatric Hemodialysis Patients
|10 to 20 kg||>20 kg|
Each dose of a 10-dose course
|0.5 mL (25 mg)||
1.0 mL (50 mg)
|2.0 mL (100 mg)|
Table IV-5. Iron Dextran Dosing Recommendations for Pediatric Predialysis and PD Patients
|10 to 20 kg||>20 kg|
|Iron dose||125 mg||250 mg||500 mg|
Volume of saline for infusion
|75 mL||125 mL||250 mL|
There have been no studies of the maintenance use of IV iron in pediatric patients. There is no rationale for prescribing oral iron supplements, given their inconvenience, cost, and side effects, when IV iron is required.
Another recommendation of the European Erythropoetin Symposium regarding iron supplementation during Epoetin therapy was as follows: IV iron is preferable for hemodialysis patients and may also be appropriate for some patients on CAPD and for some CKD patients not on dialysis.148
The rationale for recommending regular amounts of IV iron therapy to patients receiving Epoetin for treatment of anemia of CKD is that:
1. Erythropoiesis requires both iron and erythropoietin.
2. Oral iron fails to maintain adequate iron stores in most hemodialysis patients, resulting in persistence of moderate anemia, which increases morbidity and mortality.
3. The use of IV iron will increase Hgb/Hct, and therefore improve morbidity and survival in CKD patients.
4. The health benefits of IV iron are expected to exceed its adverse effects (see Guideline 9: Administration of a Test Dose of IV Iron Dextran), resulting in a net health benefit.
The Use of Intravenous Iron Preparations
There are two iron dextran preparations available for IV use in the United States, INFeD® and Dexferrum®, both of which are clinically effective. In 1999 the intravenous iron preparation, ferric sodium gluconate, Ferrlecit®, and in 2000 iron sucrose were approved for use by the Food and Drug Administration. Ferric sodium gluconate and iron sucrose have had extensive use in Europe and other countries and there is literature regarding their safety and efficacy.134,140,144,145,166,167,171-175 Intravenous iron dextran may cause dose-related arthralgias and myalgias, as well as idiosyncratic reactions (anaphylactic-like, hypotension) that are not dose-related (see Guideline 9: Administration of a Test Dose of IV Iron Dextran). Dose-related adverse effects occur infrequently and are generally mild when doses of ñ100 mg are used.176,177 It is therefore recommended that in-center hemodialysis patients be given no more than 100 mg per dose of iron dextran IV to minimize the dose-related arthralgias/myalgias. The use of frequent, small doses of iron dextran, given as an IV "push" over 2 minutes, is also more economical than giving larger boluses administered as an intravenous infusion in dextrose in water or saline.178 However, it is not realistic to expect a CKD, home hemodialysis, or PD patient to come to a clinic for 10 consecutive weeks to receive a cumulative iron dose of 1,000 mg in 100 mg increments. Therefore, for CKD, home hemodialysis, and PD patients who, despite oral iron supplementation, have developed evidence of iron deficiency, it is reasonable to administer IV iron dextran (in the clinic or dialysis center) in single doses of 500 to 1,000 mg diluted in 250 mL of normal saline and infused over 1 hour, and repeated as often as necessary to maintain adequate iron stores. Patients should be informed of the increased incidence of myalgias/arthralgias associated with such doses.
Intravenous ferric sodium gluconate is now available in 62.5 mg/5.0 mL ampules. This form of IV iron has been claimed to cause "oversaturation" of transferrin, leading to hypotension, caused by free iron.167 However, it is now known that the term "oversaturation" may be an artifact, depending on how serum iron is measured in the clinical laboratory. One method used in the United States utilizes an acetate buffer with hydroxylamine hydrochloride, which mainly measures iron bound to transferrin (true bioavailable serum iron). However, a method that uses a buffer with ascorbic acid and guanidine, releases more iron from recently administered IV iron compounds, thus artifically raising the serum iron level, and contributing to possible "oversaturation" of transferrin, thus overestimating availability of "free iron."179 If the ascorbic acid/guanidine buffer method is utilized, infusion of 62.5 mg over the course of 4 hours of dialysis will avoid this artifact, whereas the infusion of the same amount over 30 minutes and the infusion of 125 mg over 4 hours may result in transient "oversaturation" of transferrin.167 However, few adverse effects were reported when 62.5 mg and 125 mg doses of iron gluconate were mixed in 50 or 100 mL of saline, respectively, and infused over 30 or 60 minutes.165 Clinical trials are now in progress to determine whether bolus infusions of these amounts of iron gluconate over 5 to 10 minutes are safe. However, the infusion of more than 125 mg of iron gluconate as a bolus or infusion is not recommended at this time by the manufacturer. Therefore, the way in which intravenous iron is administered should depend upon the form of iron preparation that is used and the amount. Also, shortly after the IV administration of iron preparations, spuriously high transferrin saturation levels may occur due to the measurement of circulating drug iron.
Possible Adverse Effects Related to Intravenous Iron Preparations The safety of IV iron dextran, iron gluconate, and iron sucrose must be considered before recommending their routine use in adult or pediatric patients as part of the overall approach to the management of anemia of CKD. There are very few large-scale studies that have examined the incidence of adverse effects associated with these preparations.180 The incidence of life-threatening/serious acute reactions to IV iron dextran has been reported to be 0.65% (3 of 471 general patients)176 and 0.7% (4 of 573 dialysis patients).181 Because patients may have a serious adverse reaction to IV iron dextran after having received IV iron dextran without incident in the past, and because patients who have a serious adverse reaction to IV iron dextran tend not to receive IV iron dextran again, the rate of serious or potentially life-threatening adverse reactions to IV iron dextran, as a proportion of injections, rather than patients, is even smallerapproximately 0.1%.176 Although this incidence is low, it suggests that 1,200 life threatening/serious acute reactions could occur in the 200,000 hemodialysis patients in the United States if all received IV iron dextran. Some data are based on patients who received iron dextran formerly sold as Imferon®,176 which is no longer produced in the United States, and InFeD®,181 whose molecular weight is 96,000. Most of the reported adverse events were related to the use of Imferon. It is not clear whether the incidence of side effects from InFeD® is identical to that from Imferon®.182 Another intravenous iron dextran preparation, DexFerrum® has a molecular weight of 265,000.168,180 There are no published data documenting the incidence of adverse events with the use of DexFerrum®. Prospective information needed to compare reaction rates between these two agents (InFeD® and DexFerrum®) is lacking. In the absence of information on mechanism of reaction, patients who have shown severe reactions to either agent should not be administered the other.
Delayed reactions to IV iron dextran, characterized by arthralgias and myalgias, are dose-related and rarely occur with doses of 100 mg or less.176 By contrast, as many as 59% of patients experience the arthralgia-myalgia syndrome after total dose infusion (TDI).183-186 Occurrence of an arthralgia-myalgia reaction should prompt a decrease in the dose of IV iron dextran administered. Low dose administration, however, may require more frequent dosing to maintain optimum iron status. Although arthralgias and myalgias have been reported with iron gluconate, these are acute, rather than delayed, and are likely attributable to the same mechanism as the arthralgias and myalgias associated with iron dextran. The relationship of arthralgias and myalgias to the rate of administered dose or total dose of iron gluconate has not been examined.
Use of ferric sodium gluconate (Ferrlecit®) may rarely be associated with hypotension and flushing, loin pain and intense upper gastric pain, the latter without hypotension.175 A subsequent report from the same institution regarding the same iron preparation claimed that there were no immediate or delayed adverse effects, when 62.5 mg was diluted in 50 mL of saline and given over 30 minutes.172 Another report describes a study in which ferric gluconate was administered to three patients who were also receiving an ACE inhibitor. These patients all had iron deficiency and had normal renal function. One patient received 120 mg of ferric gluconate daily and, after the fourth infusion, developed abdominal cramps and hypotension.176 Two other patients received 62.5 mg of ferric gluconate and developed abdominal cramps, diarrhea, and hypotension 1 hour after the end of a slow infusion of the compound. It is not clear whether the use of an ACE inhibitor was a factor in these reactions. Reactions to iron gluconate are somewhat less common than to iron dextran, and of lesser severity. There have been no reported deaths due to the IV use of iron gluconate.180 In the hemodialysis patients participating in one of the first US trials with sodium gluconate,there is no evidence that patients who react to iron dextran will react to iron gluconate.165
One report166 noted that if transferrin levels were less than 180 mg/dL, free iron might occur if 100 mg of iron saccharate were administered. The administration of doses of 10, 20, or 40 mg of iron saccharate did not result in free iron.
Iron sucrose (Venofer) has completed clinical trials in the United States, and is used extensively in Europe and Israel. The FDA approved this drug in November 2000. It is available in 100 mg (5 mL) vials.
Since there are so little data published concerning the possible adverse effects of IV iron preparations, the Anemia Work Group recommends the establishment of a registry for monitoring the incidence of severe, acute, adverse reactions to IV iron in CKD patients. Such a registry should be designed by a committee of clinical, scientific, and methodological experts, maintained by parties, such as NKF-KDOQI, without an economic interest in parenteral iron or Epoetin therapy, and used to provide periodic, published reports.
There is little information in the literature which clearly establishes the upper limit of safety for serum ferritin in patients receiving IV iron therapy. For instance, iron overload has been defined as being present when the serum ferritin chronically remains above 1,000 ng/mL154 or above 500 ng/mL153 by the same authors. On the other hand, a study in which bone marrow iron stores were assessed in conjunction with serum ferritin levels in Epoetin-treated dialysis patients indicated that iron overload was not present in conjunction with a serum ferritin level as high as 1,047 ± 445.183 While accumulation of iron in tissues such as the heart, liver, and pancreas (as seen in primary hemochromatosis) can be hazardous, most of the iron accumulation from iron overload in dialysis patients is in the reticuloendothelial cells,169 with very little parenchymal cell damage.187 Iron deposition in proximal muscle was demonstrated in 10 iron overloaded hemodialysis patients, whose serum ferritin levels were 1,030 to 5,000 ng/mL.188 However, these patients inherited the hemochromatosis alleles. Liver cell damage was noted in the pre-Epoetin era when some adult and pediatric dialysis patients developed transfusional hemosiderosis and had serum ferritin levels in excess of 7,500 ng/mL and TSAT levels greater than 88%189,190 (Endnote l). However, it is difficult to separate the effect of hepatitis B or C, which commonly occurred in this setting, from the effect of iron overload per se.
Transferrin, which is present in plasma and lymph, normally is not more than 50% saturated with iron. In this setting, there is no free iron available for cell growth of microorganisms.191 An increased incidence of bacterial infections has been reported to be associated with iron overload.192-194 However, there is a dichotomy between the in vitro and in vivo data as to whether iron suppresses phagocytosis192,195,196 and whether iron overload induces infection.197 It is known that anemia is associated with an increased incidence of infection, that idiopathic hemochromatosis is not associated with an increased incidence of infection and that patients with thalassemia who receive multiple transfusions and develop hemosiderosis only develop an increased incidence of infections if they have had a splenectomy.197 Furthermore, it is difficult to differentiate between the immunological suppression that results from multiple transfusions and any effect of iron overload per se in causing bacterial infections (Endnote m). A more recent study by authors who had earlier noted an increased incidence of infection in association with high serum ferritin levels (Endnote m)194 in anemic hemodialysis patients prior to the advent of Epoetin therapy re-examined this issue and found that anemia (Hgb ñ9 gm/dL), and not an elevated serum ferritin level, is a risk factor for an increased incidence of bacteremia.198 The polymorphonuclear granulocyte dysfunction that may be present in iron-overloaded dialysis patients has been shown to normalize following either desferoximine or Epoetin therapy with serum ferritin levels still remaining greater than 1,000 ng/mL.199,200 On the other hand, neutrophil dysfunction has also been noted in hemodialysis patients who are not iron overloaded, but who are receiving IV iron, with transferrin saturation values <20% associated with serum ferritin levels >650 ng/mL.201 Whether this dysfunction occurred because of associated inflammatory state or was related to functional iron deficiency is not clear. Moreover, since serum ferritin is an acute phase reactant, infection may increase the serum ferritin level into a range consistent with iron overload. In such circumstances, the association between an increased ferritin level and an increased incidence of infections is due to infection resulting in an increased ferritin level, rather than iron overload resulting in an increased risk of infection.
After reviewing this literature, the Anemia Work Group concluded that maintaining a serum ferritin level within the range recommended in these guidelines is unlikely to expose the patient with CKD to an increased risk of bacterial infections. Furthermore, in hemodialysis patients, because of repetitive dialyzer blood losses, serum ferritin levels will decline by withholding IV iron, as noted in two studies where the serum ferritin levels decreased from 754 ± 34 ng/mL and 836 ± 393 ng/mL to 183 ± 18 ng/mL and 477 ± 267 ng/mL, respectively, within 4 and 3 months.166,181 Furthermore, iron overload, if present, can be reduced by the combination of increased Epoetin therapy and regular phlebotomy.202
Available evidence demonstrates that:
1. Both iron and erythropoietin are needed to produce red blood cells; as a result, unless adequate iron is available, Epoetin will be relatively ineffective.
2. In the absence of provision of supplemental iron, iron deficiency is almost always present in nontransfused hemodialysis patients receiving Epoetin.
3. Although some hemodialysis patients have been able to avoid absolute and functional iron deficiency by taking only oral iron supplements, most hemodialysis patients require IV iron to maintain sufficient iron to achieve and maintain an Hgb (Hct) of 11 to 12 g/dL (33% to 36%).
4. Just as there is risk associated with the failure to use IV iron (because many patients will be anemic unless they receive IV iron, and anemia is associated with increased morbidity and mortality), there also is some risk associated with the use of IV iron dextran and ferric sodium gluconate (see Guideline 9: Administration of a Test Dose of IV Iron Dextran).
5. Although no tests are perfect indicators of the adequacy of iron stores, the TSAT and serum ferritin are the best measures of the bodys iron status that we currently have. The probability that iron deficiency is present increases as the values of these measures decrease.
6. Given the prevalence of iron deficiency in CKD patients, and the sensitivity and specificity of TSAT and serum ferritin in detection of iron deficiency, the likelihood of iron deficiency is sufficiently high when TSAT is <20% and the serum ferritin is <100 ng/mL. Therefore, the TSAT and serum ferritin should be maintained at a level of >20% and >100 ng/mL, respectively, in all patients.
7. Because many patients will still be functionally iron deficient even with a TSAT >20%, and/or serum ferritin >100 ng/mL, additional iron should be given to patients whose TSAT is >20% and/or serum ferritin is >100 ng/mL, whenever the Hct is <33% and/or Epoetin doses are greater than anticipated, so long as administration of such iron does not chronically maintain the TSAT at >50% or serum ferritin at >800 ng/mL. There is no single level of TSAT or serum ferritin that is optimal for all patients. The goal of iron therapy is to improve erythropoiesis, not to attain specific levels of TSAT and/or serum ferritin.203 The probability that functional iron deficiency exists despite a TSAT >20% is greater in patients who require higher doses of Epoetin.
8. The levels of TSAT or serum ferritin above which patients will have iron overload is not known. Patients with transfusional hemosiderosis have a TSAT >80%.190 There is no known risk associated with a TSAT that is ñ50%. Conversely, there is no physiologic or clinical rationale for maintaining TSAT >50%. Serum ferritin levels between 300 and 800 ng/mL have been common in dialysis patients, and there has been no evidence that such levels are associated with adverse, iron-mediated effects.
9. Because of the repetitive dialyzer-related blood losses in hemodialysis patients, iron overload can be avoided by temporarily withholding IV iron administration if TSAT or ferritin levels temporarily become too high.
10. By monitoring the TSAT and serum ferritin at least once every 3 months,
erythropoiesis can be optimized in hemodialysis patients by adjusting the pro-rated
weekly dose of IV iron to maintain adequate iron status.
Administration of a Test Dose of IV Iron
Prior to initiating IV iron dextran therapy, a one-time test dose of 25 mg (in adults) should be given IV. For pediatric patients weighing <10 kg, the test dose should be 10 mg; for pediatric patients weighing 10 to 20 kg, the test dose should be 15 mg. If no immediate allergic reaction occurs, subsequent routine doses can be given without a test dose. According to the package insert, iron dextran should be administered by slow IV push at a rate not to exceed 1.0 mL (50 mg, if undiluted) per minute. (Opinion)
Prior to initiating IV iron gluconate therapy in adults, a one-time test dose of 25 mg should be given IV. If no immediate allergic reactions occurs, subsequent routine doses can be given without a test dose. According to the package insert, the test dose should be diluted in 50 mL 0.9% sodium chloride for injection and administered over 60 minutes. Also, according to the package insert, iron gluconate has not been established to be safe and effective in pediatric patients.
Rationale Acute adverse reactions may be seen with administration of IV iron dextran and IV iron gluconate. In addition, delayed reactions may be seen with the use of IV iron dextran. Severe acute reactions resembling anaphylaxis with dyspnea, hypotension, chest pain, angioedema or urticaria are uncommon. Anaphylaxis-like reactions occur in fewer than 1% of iron dextran or iron gluconate administrations. Fatalities associated with the use of iron dextran are rare176,181 and have not been reported in association with the use of iron gluconate.175 A history of multiple drug allergies is associated with increased risk of an acute iron dextran reaction,176 but a similar association has not been reported for iron gluconate. Anaphylaxis-like reactions to iron dextran usually occur within a few minutes after injection and typically respond readily to treatment with IV epinephrine, diphenhydramine, and corticosteroids. It is common practice to wait 15 to 60 minutes after the initial test dose before the remainder of the initial therapeutic dose is injected, assuming no initial anaphylaxis-like reaction occurred. It is recommended that the test dose and subsequent doses of iron dextran, iron gluconate, or iron sucrose be administered by personnel trained to provide emergency treatment and that there be immediate access to the medications needed for the treatment in the rare case of a serious allergic reaction.
Table IV-6. Amount of Elemental Iron and Cost of Various Oral Iron Preparations208
Iron Preperation (without added vitamins or folic acid)
|Tablet Size (mg)||Amount of Elemental Iron (mg)||Average Monthly Wholesale Cost (200 mg/day*)|
|* Of elemental iron.|
| 150 mg iron per day.|
Test doses for iron dextran and iron gluconate are not interchangeable. An uneventful response to either agent does not preclude an adverse reaction to the other or to repeat administration of the same agent. It should be noted that a test dose for either iron dextran or iron gluconate has limited value. There is no evidence that acute, anaphylaxis-like reactions to iron dextran or iron gluconate are less severe after a 25 mg test dose than after a therapeutic 100 or 125 mg dose. For iron dextran, most patients who suffer severe acute reactions have successfully received both a test dose and multiple therapeutic doses in the past. For iron gluconate it is likely that the same phenomenon will be observed, although data on this point are not currently available. Thus, the test dose neither minimizes reaction to a first dose nor prospectively identifies the patient at increased risk for a severe reaction to a later dose. Caution is warranted with every dose of iron dextran that is administered.
Oral Iron Therapy
When oral iron is used, it should be given as 200 mg of elemental iron per day, in 2 to 3 divided doses in the adult patient, and 2 to 3 mg/kg/day in the pediatric patient. Oral iron is best absorbed when ingested without food or other medications. (Evidence)
Rationale In CKD and PD patients with minimal daily iron losses, provision of 200 mg elemental oral iron per day may be sufficient to replace ongoing losses and support erythropoiesis. Intestinal absorption of iron is inversely related to iron stores.155,156 Iron absorption is also increased as erythropoiesis increases, such as occurs with Epoetin therapy.150,159,160 While studies in the pre-Epoetin era indicated that iron absorption was minimal with serum ferritin levels above 100 ng/mL and TSAT values above 20%, the amount of iron absorbed in CKD patients in the presence of Epoetin therapy remains poorly documented. One study indicated minimal absorption if the serum ferritin was greater than 100 ng/mL.157
If oral iron is used, it should be in the form of one of the ionic iron salts, such as iron sulfate, fumarate, or gluconate, because they are the cheapest and provide known amounts of elemental iron. Iron polysaccharide, which is more expensive, is no better tolerated (no less nausea, vomiting, or abdominal discomfort leading to discontinuation) than ionic iron salts.204 Despite the perception by some that iron polysaccharide is more effective than the other iron salts, there have been no well-designed clinical studies which support that perception. In one study in which iron polysaccharide was one of four oral iron preparations given to Epoetin-treated hemodialysis patients,150 this form of iron was associated with the smallest rise in mean Hct and the only mean Hct that was not significantly increased from baseline after 6 months of therapy.
When food is eaten within 2 hours before or 1 hour after an oral iron supplement, the food will reduce iron absorption by as much as one half.205 Aluminum-based phosphate binders can also reduce iron absorption.206 Ascorbic acid does not improve ferrous iron absorption.207
Patients who have difficulty tolerating oral iron supplements may benefit from smaller, more frequent doses, starting with a lower dose and increasing slowly to the target dose, trying a different form or product, or taking the supplement at bedtime.
Table IV-6 provides information on the amount of elemental iron in different preparations and the monthly cost of taking 200 mg of elemental iron per day.
The standard oral iron supplement in a child is 2 to 3 mg/kg/day of elemental iron in divided doses. There are oral liquid iron preparations that might be more applicable for young pediatric patients than the solid dose forms noted in Table IV-6.
© 2001 National Kidney Foundation, Inc