OPEN-LABEL, CONTROLLED-STUDY ON THE METABOLIC AND ABSORPTIOMETRIC EFFECTS OF CALCITRIOL IN INVOLUTIONAL OSTEOPOROSIS

Calcitriol 0.5 mu g twice daily, in combination with a low dietary cal cium intake, was administered for 2 years to 35 women (mean age 64.6 /- 8.3 years) with involutional osteoporosis; 35 women (mean age 63.5 +/- 8.7 years) with osteoporosis ingested dietary calcium 1000 mg/day and were considered a control group. Total body bone mineral density ( BMD) and BMD of major anatomical areas were measured (Lunar DPX). In t he calcitriol group, significant increases in serum and urinary calciu m levels were observed after 12 and 24 months; urinary hydroxyproline excretion did not change significantly. No differences in blood urea n itrogen or serum creatinine were observed during calcitriol therapy, a nd none of the patients experienced symptomatic renal lithiasis. Incre ases in total body, spine and leg BMD were observed after 12 and 24 mo nths of calcitriol therapy (+0.63%, +1.15% and +0.56%, and +0.85%, +1. 37%, and +0.35%, respectively). In the control group, total body BT?ID and BMD of the spine, trunk, arms and legs decreased significantly. T he mean percentage BMD differences between the 2 study groups were sta tistically significant. In the control group, spinal height declined p rogressively and significantly from baseline (-1.61% and -3.02% after 12 and 24 months, respectively), while in calcitriol-treated patients the decrease was less marked (-1.11% and -1.15%, respectively): the di fference between the 2 groups was statistically significant (p < 0.01) after 24 months. In conclusion, calcitriol 1 mu g/day plus a low diet ary calcium intake may be considered safe and effective in patients wi th involutional osteoporosis.