Bone turnover in patients on home parenteral nutrition: a longitudinal observation by biochemical markers

In order to characterize biochemical markers of bone turnover in home parenteral nutrition(HPN) patients, 8 adult patients on HPN for benign intestinal failure were studied at 0, 6 and 12 months by evaluating serum osteocalcin (bone formation marker), urinary hydroxylysyl pyridinoline, lysyl pyridinoline and beta-galactosyl hydroxylysine (bone resorption markers), serum PTH, Calcitonin, 25 vitD, 1-25vitD, serum and urinary minerals, body weight, rehabilitation degree and HPN characteristics. Three patients entered the study 2-3 months after the beginning of HPN. Their features of bone turnover were homogeneous, characterized by increased resorption associated with normal or increased formation, at baseline, and normalization of resorption associated with an increase or a parallel decrease of formation, at 6 months. At 12 months, the patterns were similar to those observed at 6 months. The patients were not of the same sex and age and had different underlying diseases and types of intestinal failure, HPN composition and serum vitamin D levels. They had weight gain that was already present at baseline and the positive outcomes of the rehabilitation and clinical status in common. Five patients entered the study more than 1 year after the beginning of HPN. They showed heterogeneous features of bone turnover that were stable throughout the study, characterized by increased resorption associated with low or normal formation in two cases, low normal resorption associated with low or normal formation in three. In one patient, who had increased resorption and low formation, the bone turnover appeared to be explained by the nutritional and clinical outcomes, which were negative. These results appeared consistent with those obtained in previous studies by bone histomorphometry, indicating that bone turnover of short-term HPN patients differed from that of long-term patients, and suggesting that the early months of HPN were associated with increased bone resorption.