Vitamin D levels and bone turnover markers are not related to non-alcoholic fatty liver disease in severely obese patients.

BACKGROUND Morbidly obese patients usually present vitamin D deficiency or secondary hyperparathyroidism. Low vitamin D levels have been recently related to non-alcoholic fatty liver disease (NAFLD). The aim of this study was to analyse the relationship between vitamin D, bone turnover markers and non-alcoholic fatty liver disease and metabolic syndrome in severely obese patients. METHODS One hundred and ten patients who underwent bariatric surgery were included. Liver biopsy was taken during surgery. Two univariate analyses were carried out in order to i) analyse the relationship between liver histology and vitamin D-bone turnover markers (intact parathyroid hormone (PTH), osteocalcin and Carboxy-terminal collagen crosslinks) and ii) establish the association between metabolic syndrome components-insulin resistance (HOMA) and vitamin D-bone turnover markers. RESULTS 70% of the patients had lower levels of vitamin D or secondary hyperparathyroidism. None of the components of liver histology were associated with levels of vitamin D or with bone turnover parameters. Patients with metabolic syndrome showed lower levels of PTH and osteocalcin (72,42 (29,47) vs 61.25(19.59) p-Value: 0.022; 19.79 (10.43) vs 16.87(10.25) p-Value: 0,028, respectively). HOMA was not related to Vitamin D or bone turnover markers. CONCLUSION Low levels of vitamin D or hyperparathyroidism are common in severely obese patients. Vitamin D and bone metabolism markers were associated neither to NAFLD nor with metabolic syndrome in our series of obese morbid patients.