Abstract
Effects of dietary salt intake on serum concetration and renal excretion of sodium and potassium were studied in seven children with chronic renal failure (CRF) (5 girls, 2 boys) . Ages were 4 to 14 years with a mean of 11 years 9 months, and GFR 2 to 24 ml/min/ 1.48m2. The patients were given an ordinary salt diet (salt intake 4-7.5g/day), a low or nil salt diet (less than 0.5g/day) and a high salt diet (8-15g/day) . Daily protein intake was 1 to 2g/kg body weight and water was given ad libitum. Renal excretion of sodium and potassium was evaluated in terms of clearance (C) and fractional excretion (FE) of both elements. Nine patients who had chronic renal diseases and whose GFR were over 36ml/min/1.48 m2 served as controls. Some CRF patients showed hyponatremia on an ordinary salt diet, which was also seen on a low or nil salt diet and on a high salt diet. The low or nil salt diet significantly increased CNa. Changes in CNa after salt restriction and loading were greater in controls than in CRF patients. FENa increased as creatinine clearance (CCr) was reduced and there was a clear hyperbolic relation between FENa and CCr. Neither salt deprivation nor loading had essential effects on FENa. Serum concentrations of potassium increased as CCr decreased. This finding was also seen during salt restriction and salt loading. CK was low in CRF patients and unchanged during salt restriction and salt loading. CK was significantly higher in controls than in CRF patients both on an ordinary salt diet and on a high salt diet. FEk was increased as CCr decreased, and there was a hyperbolic relation between FEk and CCr during both salt deprivation and salt loading.
