Potassium Metabolism and Management in Patients with CKD

Abstract

Potassium (K), the main cation inside cells, plays roles in maintaining cellular osmolarity and acid-base equilibrium, as well as nerve stimulation transmission, and regulation of cardiac and muscle functions. It has also recently been shown that K has an antihypertensive effect by promoting sodium excretion, while it is also attracting attention as an important component that can suppress hypertension associated with excessive sodium intake. Since most ingested K is excreted through the kidneys, decreased renal function is a major factor in increased serum levels, and target values for its intake according to the degree of renal dysfunction have been established. In older individuals with impaired renal function, not only hyperkalemia but also hypokalemia due to anorexia, K loss by dialysis, and effects of various drugs are likely to develop. Thus, it is necessary to pay attention to K management tailored to individual conditions. Since abnormalities in K metabolism can also cause lethal arrhythmia or sudden cardiac death, it is extremely important to monitor patients with a high risk of hyper- or hypokalemia and attempt to provide early and appropriate intervention.

Keywords: CKD; blood pressure; hypertension; potassium; potassium excretion; salt; sodium.

Figure 1

Factors affecting potassium metabolism in chronic kidney disease. Various factors cause abnormal K metabolism in affected patients. Although sweat and the intestinal tract provide compensatory mechanisms, correction with medication is also usually needed.

Figure 2

Potassium dynamics in DM/non-DM dialysis patients (data from previous research). N-PCR was significantly and positively correlated with serum K levels at the pre-Monday or pre-Tuesday HD session, and interdialytic serum K gain from post-weekend HD to the next session (a,b), whereas no relationship was noted in the non-DM group (c,d).

Figure 3

Role of potassium in CKD pathogenesis. Elevated serum K has protective effects on the kidneys by promoting salt excretion and reducing renal function by acidosis due to suppression of NH₃ production. On the other hand, decreased serum K reduces renal function with a direct negative effect on renal tissue.