The main purpose of our study was to verify the effect of a very-low-
protein, low-
phosphorus diet, supplemented with
essential amino acids and keto analogues and with
calcium carbonate, on circulating levels of intact
parathyroid hormone (i-PTH) in severe
chronic renal failure patients with
secondary hyperparathyroidism, not treated with any
vitamin D preparation. To this aim, we shifted 21 chronic uremics (12 males, 9 females; age 56 +/- 13 years) with serum
creatinine >6.5 mg/dl and i-PTH >150 pg/ml, from a standard
low-protein diet (0.6 g/kg/day approximately) to a very-low-
protein (0.3 g/kg/day), very-low-
phosphorus (5 mg/kg/day) diet supplemented with a mixture of
essential amino acids and
calcium keto analogues (Ketodiet),
calcium carbonate (2-4 g/day),
iron, and
vitamin B12 preparations. The energy supply of both diets was 30-35 kcal/kg/day. Exclusion criteria were a poor compliance with dietary or supplement prescriptions or signs of autonomic
hyperparathyroidism. After 4 +/- 2 months of Ketodiet, the i-PTH serum levels decreased by 49% as a mean (from 441 +/- 233 to 225 +/- 161 pg/ml, p < 0.001); serum
phosphorus and
alkaline phosphatase decreased, whereas serum
calcium increased. The great reduction of serum and urinary
urea demonstrated a good compliance with Ketodiet, and no sign of
protein malnutrition was observed. These findings confirm that even in severe chronic uremic patients
dietary phosphorus restriction and
calcium carbonate supplementation lower i-PTH serum levels. This is one of the goals of the dietary treatment that can be safely achieved, provided good compliance both with the dietary prescriptions and with adequate energy and supplement intakes.