Osteodystrophy is a major complication of end-stage liver disease, especially in postmenopausal women. Our aim in this study was to evaluate bone metabolism and gonad function in men undergoing orthotopic liver transplantation (OLTx). Twenty-three consecutive men (mean age 48 +/- 13 years) evaluated for OLTx were studied, assessing the following parameters at baseline and 3, 6, 12 and 24 months after OLTx: lumbar spine (L2-L4) bone mineral density (BMD), parathyroid hormone (PTH), osteocalcin (BGP), 25-hydroxyvitamin D (250HD), free testosterone (FT) and gonadotropins (FSH, LH). At baseline, 12 patients (52%) had a T-score < -2.5 SD and the mean BMD was 0.806 +/- 0. 11 g/cm(2) (range 0.470-1.045 g/cm(2)). The BMD was lower 3 months after OLTx and significantly higher 12 and 24 months after OLTx. A significant increase in serum BGP was observed at 6, 12 (p < 0.05) and 24 months (p <0.005) after OLTx. The mean serum PTH level was 26.6 +/- 3.1 pg/ml at baseline and increased significantly at 12 and 24 months (to 49.4 +/- 9.9 and 61.2 +/- 10.1 pg/ml, respectively, p <0.05). 250HD serum levels were low at baseline and returned to the normal range after 12 and 24 months (baseline, 8.73 +/- 1.54 ng/ml; 12 months, 16.4 +/- 2.6 ng/ml, 24 months, 17.67 +/- 3.1 ng/ml; p <0.05). FT was significantly lower at baseline than in a group of 10 healthy controls (5.09 +/- 10.99., vs 10.3 +/- 1.1 pg/ml; p <0.0001). After OLTx a significant increase in FT was recorded at 6, 12 (p <0.05) and 24 months (p <0.005). FT was not correlated with BMD, however. After OLTx an increase in FSH and LH was observed (but failed to reach statistical significance) at 3 and 6 months, followed by a slight reduction at 12 and 24 months. Thus a high proportion of men with end-stage liver disease do have osteoporosis. After OLTx, an early recovery of gonad function is observed, followed by an increase in bone mass, which occurs from the sixth month onward.