Elevated Serum Potassium Linked to Higher Mortality in over 2 Million Patients

Boston, MA - Both low and high levels of serum potassium are associated with an increased risk of mortality, according to research results presented at the National Kidney Foundation 2016 Spring Clinical Meetings.

Extremely high or low potassium levels are life-threatening but the frequency and the risks associated with milder potassium abnormalities (outside the normal range of 3.5 to 5 mmol/L) is less well understood.

“There is also a suggestion that potassium levels differ across racial groups, either due to diet or excretion, and these differences and their relationship to medications and risks need to be better understood,” said Morgan Grams, MD, PhD of Johns Hopkins School of Medicine.

Researchers from Johns Hopkins University collaborated with researchers at the University of Tennessee Health Science Center, the Memphis VA Medical Center and University of California Irvine to evaluate outpatient testing records among 2.7 Million US veterans over a two-year period.

High serum potassium concentration (>5 mmol/L) was present in 4.2% (>5.5% in 0.6%) and low serum potassium concentration (<3.5 mmol/L) was present in 2.8% of the patients undergoing outpatient laboratory testing.  The researchers further classified abnormally high levels, called hyperkalemia, as transient (assessed as one-time elevations), intermittent (≤50% of tests elevated), and persistent (>50% of tests elevated >5 mmol/L).

Researchers found that African-Americans were more likely to have low levels and less likely to have high levels than white patients, but both low and high levels outside the tightly regulated range for serum potassium were associated with an increased risk of mortality in all groups. 

Elevated potassium was also associated with a higher risk of subsequent kidney failure requiring dialysis or a kidney transplant. Although black persons had lower potassium levels, the association between potassium and mortality and kidney failure was similar by race.

Both transient and persistent elevations were strongly associated with poorer kidney function, diabetes and use of angiotensin converting enzyme medications after adjusting for a wide range of factors

Potassium balance is integral for many physiological functions. Physicians often check potassium levels to determine the need for changing medications or diet or adding new agents to control abnormally high potassium levels.

“In our study, the risk of mortality subsequent to potassium testing was elevated among patients with both low and high levels emphasizing the utility of this laboratory measure,” said Josef Coresh, MD, PhD, of the Bloomberg School of Public Health and Johns Hopkins School of Medicine. “This research should inform the interpretation of serum potassium levels and attempts to optimize patient outcomes.”

The NKF 2016 Spring Clinical Meetings are being held April 27 to May 1, in Boston, MA. For additional program information, visit www.NKFClinicalMeetings.org.

The National Kidney Foundation is the leading organization in the U.S. dedicated to the awareness, prevention and treatment of kidney disease. For more information, visit www.kidney.org