Potassium deficiency in chronic renal failure

Abstract

That total body potassium depletion may occur in the presence of a normal or high serum K+ concentration in patients with end stage renal disease is controversial. Since muscle K+ stores are the best single index of body potassium stores, the authors measured skeletal muscle water, Na+, K+ and Cl- content in volunteers, in patients with stable chronic renal failure (CRF) and in patients maintained on chronic hemodialysis (CHD). Skeletal muscle resting membrane potential [E(m)], measured in the anterior tibial compartment to facilitate calculation of intracellular electrolyte concentrations, was immediately followed by the procurement of muscle samples, obtained by percutaneous needle biopsy of the thigh. Chronic renal failure was associated with a high intracellular Na+ concentration; (20.4 mEq/liter of intracellular water (ICW); normal = 11.4, P < 0.001), a low intracellular K+ concentration, (126 mEq/liter of ICW; normal = 155, P < 0.001) and a low E(m) (-76.7 mv; normal = -86.7 mv, P < 0.001). After chronic hemodialysis for 6 wk duration, the intracellular electrolyte concentration returned to normal but the E(m) remained low (-75 mv). The authors conclude that K+ deficiency is common in advanced CRF despite a normal serum K+ concentration, and is corrected by hemodialysis.