Answers to Your Health Questions
Ask the Doctor with Dr. Leslie Spry MD, FACP
Q: How does smoking affect your kidneys?
A: Smoking has many negative effects on your health. I think of smoking as a way of stepping on the accelerator for any disease that you may have. Any disease that affects the kidney, such as diabetes and high blood pressure, is also made worse by smoking. For example, smoking can interfere with medicines used to treat high blood pressure. Uncontrolled or poorly controlled high blood pressure is a leading cause of kidney disease. Smoking also slows the blood flow to vital organs like the kidneys and can worsen already existing kidney disease. Hence, smoking not only causes lung cancer and lung disease, but makes other diseases such as kidney disease and heart disease worse. Smoking is also associated with kidney cancer and bladder cancer. Quitting smoking is difficult but if you speak to your healthcare provider they can offer suggestions to help you quit.
Q: How do salt intake and your food choices affect your heart and kidneys?
A: Under normal circumstances, the heart and kidneys are more able to sort out whatever diet is thrown at them and adapt. Unfortunately, if you have the genetics (family history) that put you at risk for high blood pressure, heart disease, diabetes, and/or kidney disease, high salt intake substantially increases that risk. The body can adapt to salt (sodium chloride) intakes from about 500 mg per day to well over 10,000 mg per day. The typical American diet has between 5000 and 8000 mg of salt intake per day. Many studies have shown, however, for those patients at risk for the diseases mentioned above, excess salt intake above the ideal (2000 to 3000 mg of sodium chloride per day) increases those risks and speeds up the complications of high blood pressure, heart disease and kidney disease. People with diabetes are prone to kidney disease and heart disease, and by increasing salt intake, these complications are made worse. Not all patients are at risk. White patients seem to have less risk from salt intake than blacks and Hispanics. Pacific Islanders also have excess risk from increased salt intake. Women seem to generally be more sensitive to salt intake than men. Younger patients are generally going to be less sensitive to salt than older patients. Obesity plus high salt intake is particularly potent at speeding the complications of high blood pressure, heart disease and kidney disease.
Fast foods are notoriously high in salt content. Lowering salt in the diet (such as that recommended in a DASH diet -see below) has been shown to lower blood pressure, decrease swelling and improve heart function in patients with congestive heart failure. Avoiding foods with high sodium content may also lead to weight loss.
The DASH diet (Dietary Approaches to Stop Hypertension) can be reviewed at: http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/new_dash.pdf Dietary restriction of salt intake should be at the cornerstone of all plans for therapy of heart disease and kidney disease.
Alphabet soup: Breaking down frequently used medical and health terms
CVD: Cardiovascular Disease is a general term used to describe conditions that affect the ability of the heart and blood vessels (also known as the vascular system) to pump oxygen and nutrient rich blood through the arteries to vital life-sustaining organs. A breakdown or interruption to this supply of oxygen and blood to your organs can cause serious internal damage or death.
LDL cholesterol – Low Density Lipoprotein or “bad cholesterol”. LDL gets this bad reputation because of its role in forming plaque on artery walls which can lead to cardiovascular disease. Your LDL cholesterol is determined by a blood test. The target range for LDL cholesterol is less than 130 mg/dL
HDL cholesterol – High Density Lipoprotein or “good cholesterol” helps to remove LDL/bad cholesterol from your blood stream. Your HDL cholesterol is determined by a blood test. The target range for HDL is greater than or equal to 40 mg/dL.
GFR – Glomerular Filtration Rate is a measurement of how much kidney function you have. It is calculated based upon the level of creatinine (a waste that comes from normal muscle activity) found in the blood as well as age, race and gender. If GFR is over 90, the kidneys are healthy and functioning normally. People with mildly low GFR (between 60 and 89) may not have kidney disease if there is no sign of kidney damage, such as protein in the urine. These people should have their GFR checked more often. When GFR is below 60 for a three-month period, that is an indicator of chronic kidney disease. People with GFR values below 60 may be referred to a nephrologist (kidney specialist) for evaluation and treatment.