Bone turnover in short-term and long-term home parenteral nutrition for benign disease

In patients on home parenteral nutrition (HPN), a previous longitudinal histomorphometric study on bone turnover showed a hyperkinetic feature in the early months of treatment that evolved to osteomalacia with low formation rate. Our purpose was to assess the variations of biochemical markers of bone turnover during HPN. Eight patients who had been receiving HPN for <4 mo (short-HPN) and eight patients receiving HPN for >12 mo (long-HPN) were studied by serum osteocalcin (OC), parathyroid hormone, 25-hydroxyvitamin D, 1,25-dihydroxivitamin D, and aluminium; urinary cross-links of collagen; serum; and urinary minerals. Short-HPN was assessed at baseline and >6 mo afterward. Long-HPN was assessed only at baseline. In short-HPN, there was a hyperkinetic turnover at baseline. At follow-up, OC was similar to baseline, whereas cross-links, urinary calcium and magnesium decreased (P < 0.03), and parathyroid hormone increased (P < 0.001). The variation of urinary calcium correlated with that of cross-links (r = 0.73, P < 0.04). In long-HPN, OC was low or low-normal in almost all the patients, and cross-links were normal. Mean OC was lower than that of short-HPN both at baseline (P < 0.003) and at follow-up (P < 0.002). The results suggest that in the early period of HPN bone metabolism improved from a hyperkinetic turnover to a positive balance. A low bone-formation rate appeared to be a characteristic feature of long-term HPN.