The optimal range of plasma potassium varies by stage of chronic kidney disease (CKD), a new study suggests.
In a paper published in Nephrology Dialysis Transplantation, investigators wrote that “although our study supports the view that hyperkalaemia is better tolerated in CKD, it challenges the current use of a single clinical K+ range for all patients.”
Juan-Jesús Carrero, PhD, of Karolinska Institutet in Sweden, and his team investigated plasma potassium levels in 831,760 participants in the Stockholm CREAtinine Measurements (SCREAM) project. Of these, 8.5% had stage 3 CKD and 1.1% stage 4 to 5 CKD. Results showed that plasma potassium increased with CKD stage from a median 3.98 mmol/L in those with an estimated glomerular filtration rate (eGFR) more than 90 mL/min/1.73 m2 to 4.43 mmol/L for those with an eGFR less than 15 mL/min/1.73 m2.
As plasma potassium increased, mortality risk dipped and then rose again in a U-shaped pattern. Each group exhibited a different safe range of plasma potassium. The optimal range associated with 90-day mortality risk was 3.45 to 4.94 mmol/L in patients with an eGFR greater than 60 mL/min/1.73 m2, but it widened in patients with CKD: 3.36 to 5.18 mmol/L for stage 3 and 3.26 to 5.53 mmol/L for stage 4 to 5.
Patients with advanced CKD may develop greater tolerance to potassium retention, the authors stated. They added that disease-specific potassium ranges may be needed so clinicians can know the exact point at which alternate therapy should be considered.
Gasparini A, Evans M, Barany P, et al. Plasma potassium ranges associated with mortality across stages of chronic kidney disease: the Stockholm CREAtinine Measurements (SCREAM) project. Nephrol Dial Transplant 2018;1–8. DOI: 10.1093/ndt/gfy249