Ketodiet, physiological calcium intake and native vitamin D improve renal osteodystrophy

The effects of a very low-protein diet (VLPD) supplemented with amino acids and ketoanalogues (KA) and with 1 g of calcium carbonate and 1000 IU of vitamin D2, were studied in 17 patients with advanced renal failure (GFR < or = 20 ml/min) over a period of one year. The protein intake was 0.3 g protein/kg body wt/day. Daily phosphorus and calcium intake were respectively 1,500 mg and 300 mg. Sequential bone densitometry was performed and bone histomorphometry after double tetracycline labeling was evaluated, before and after one year of diet. Calcium and phosphate metabolism parameters were monitored every two months. In spite of a significant decrease of GFR, phosphorus, parathyroid hormone (1-84) and osteocalcin plasma levels decreased significantly, while low plasma bicarbonate normalized, and calcitriol and calcium levels remained respectively low and normal. Before the diet, histological study disclosed four cases of mixed osteopathy: osteomalacia associated with osteitis fibrosa (OM/OF), nine pure osteitis fibrosa (OF) and four with normal bone remodeling (NB). After one year of diet, the OM component of OM/OF disappeared, as evidenced by a normalization of the mineral apposition rate and osteoid thickness. In the patients presenting pure OF, a significant decrease in osteoblastic and osteoclastic surfaces, in the number of osteoclasts, and in the bone formation rate (BFR) were found. Vertebral mineral density measured by quantitative computerized tomodensitometry did not change significantly. In conclusion, this study not only confirms the beneficial effects of VLPD + KA + calcium on uremic hyperparathyroid bone disease in advanced renal failure assessed using static bone histomorphometry, but also shows a correction of histodynamic bone parameters.(ABSTRACT TRUNCATED AT 250 WORDS)