[The critical level of renal function in patients with chronic renal failure from the aspect of maintaining normal levels of potassium in the blood].

In 29 subjects with chronic renal failure (Pkr = 826 +/- 69 mumol/, Ckr 0.128 +/- +0.039 ml/s) treated by conservative therapy the urinary excretion and residual renal potassium clearance (CK) was investigated. In 17% of these patients the plasma potassium level (PK) was higher than 5 mmol/l. The PK levels were not significantly related to the value of the residual diuresis, to the daily urinary potassium excretion nor the value of residual creatinine clearance. A significant relationship was found between values PK and CK. The critical CK value where PK rises above 5 mmol/l (under conditions of reduced protein intake 0.5 g/kd/day and a potassium intake not exceeding 40 mmol/l/24 hours) suggests the participation of extrarenal factors (excessive K intake or it's increased shift from cells to extracellular fluid).