Long-term protein intake control in kidney transplant recipients: effect in kidney graft function and in nutritional status.

BACKGROUND: Reduction in renal mass is followed by progressive renal failure. The reduction in filtration surface area, caused by the absence of 50% of renal mass, in patients with customary salt intake is followed by expansion of extracellulary volume and systemic and glomerular hypertension. High protein intake may contribute to renal allograft injury arising from insufficient renal mass. METHODS: The authors studied outcome of 48 patients with kidney transplant to whom normocaloric diets and moderate intake of protein (0.8 g/kg), of sodium (3 g/d), and lipids (no more than 30% of total energy) were prescribed. Monthly 24-hour urea excretion and 24-hour sodium excretion were measured. Renal function was assessed by creatinine clearances and by renal scintigraphy. The 30 patients who followed prescriptions exactly were the compliant group (group 1). The other 18, who followed the diet prescribed only partially (their intakes were 1.4 g/kg of protein and 5 g/d of sodium) were the control group (group 2). RESULTS: Patients of the compliant group maintained unchanged renal function, whereas patients of the control group lost more than 40% of excretion efficiency as a mean. CONCLUSIONS: Dietary restrictions of protein and sodium can stabilize renal function in patients with kidney transplant. Wider use of this treatment is indicated.