Prevention of osteoporosis after cardiac transplantation - A prospective, longitudinal, randomized, double-blind trial with calcitriol

Background. Accelerated bone loss is a well-recognized complication after c ardiac transplantation (HTx) due to immunosuppressive therapy. The purpose of this prospective, longitudinal, randomized, placebo-controlled, double-b lind study was to investigate the effect of calcitriol (1,25-dihydroxyvitam in D-3) in the prevention of bone loss and fracture rate after HTx, Methods, Basic therapy included 1000 mg of calcium daily and sex hormone re placement in hypogonadal patients. A total of 132 patients (111 male, 21 fe male; mean age: 51+/-10 years; 35+/-25 months after HTx) were randomized to 0.25 mu g of calcitriol or placebo. Bone mineral density (BMD, g/cm(2); T score, %) of the lumbar spine and x-rays for the assessment of vertebral fr actures were performed at baseline and after 12, 24, and 36 months. Biochem ical indexes of mineral metabolism were measured every 3 months, Results. Overall BMD was significantly decreased after HTx (T score 87+/-13 %), BMD increased continuously within the study period in the calcitriol gr oup (1 year: 2,2+/-4,8%; 2 years: 3.9+/-5,4%; 3 years: 5.7+/-4.4%) as well as in the placebo group (1 year: 1.8 +/- 4.9%; 2 years: 3.7 +/- 6.5%; 3 yea rs: 6.1 +/- 7.8%) without statistical difference between the groups, Fractu re incidence was low during the study interval (1 year: 2.0%; 2 years: 3.4% ; 3 years: 0%), Hypogonadism (20%) was associated with a lower BMD (78 +/- 12% vs, 88 +/- 12%; P < 0.01) and a higher increase (35%) after hormone rep lacement in comparison to normogonadal patients, Increased intact parathyro id hormone and bone resorption markers decreased significantly during thera py. Conclusions, Calcium supplementation and sex hormone replacement in hypogon adism proved a sufficient long-term prevention therapy to improve decreased BMD and to prevent fractures after HTx, Besides immunosuppression, both co ncomitant hypogonadism and secondary hyperparathyroidism play a major role in the long-term bone loss and should therefore be monitored and treated ad equately, Low-dose calcitriol demonstrated no significant extra benefit reg arding BMD and fracture rate in the long-term period after HTx.