Higher Serum Potassium Level Associated with Late Stage Chronic Kidney Disease

Background: The serum potassium (K+) level is kept in a narrow range to sustain normalphysiology within the human body by the kidneys. The serum K+level indifferent stages of chronic kidney disease (CKD) remains undefined.Methods: We conducted a cross-sectional study to observe the serum K+level inpatients without clinical manifestations of hyperkalemia in the late stages ofCKD (stages 3-5). A total of 531 patients with late stage CKD were includedand followed up for at least 1 year, from March 2006 to May 2007. Thepatients were sub-grouped by stages of CKD, which were determined by a“Modification of Diet in Renal Disease” equation estimating the glomerularfiltration rate (eGFR). The serum creatinine, eGFR and K+levels wererecorded at least twice during the study. We analyzed the average K+level inthese late-stage CKD patients.Results: The average K+level increased along with renal function deterioration in thelate stages of CKD (stage 3: 4.36 0.49; stage 4: 4.50 0.55; stage 5: 4.69 0.73 mEq/L, p < 0.05). Men and patients with diabetes mellitus, a loweGFR, and a low hemoglobin might have higher levels of serum K+. We alsonoticed that there was a linear increase in the standard deviation of the serumK+level as renal function deteriorated. The use of angiotensin-convertingenzyme inhibitors and angiotensin II receptor blockers was not associatedwith hyperkalemia in our patients.Conclusion: Our results reflected that the serum K+level increased in correlation with thedecline in the eGFR in the late stages of CKD. Also, male gender, diabetesmellitus, and anemia might be risk factors for higher K+levels in CKDpatients. The variation in the serum K+level became wider as renal failureprogressed.