THE CARBOXY-TERMINAL PYRIDINOLINE CROSS-LINKED TELOPEPTIDE OF TYPE-I COLLAGEN IN SERUM AS A MARKER OF BONE-RESORPTION - THE EFFECT OF NANDROLONE DECANOATE AND HORMONE REPLACEMENT THERAPY

Carboxy-terminal pyridinoline cross-linked telopeptide of type I colla gen (ICTP) in serum has recently been proposed as a new biochemical ma rker of bone resorption. In the present study we compared serum ICTP w ith radiopharmaceutical and histomorphometric measurements of bone tur nover in postmenopausal women with mild osteoporosis, and assessed the effect of hormone replacement therapy (HRT) (2 mg 17 beta-estradiol p lus 1 mg norethisterone daily) and anabolic steroid therapy (50 mg nan drolone decanoate (ND) i.m. every 3 weeks) on serum ICTP in two double -blind placebo-controlled studies with 55 to 75-year-old women. Serum ICTP measured by radioimmunoassay (RIA) correlated significantly with the 24-hour whole body retention of 99m-technetium diphosphonate (Rho = 0.47, P < 0.001, n = 66), but not with histomorphometric measurement s of bone turnover in iliac crest biopsies. One year of HRT (n = 16) v ersus placebo (n = 15) did not produce significant changes in serum IC TP. Compared with placebo (n = 17), 1 year of ND (n = 19) produced an increase in serum ICTP of 90 +/- 16% (P < 0.0001); 6 months after disc ontinuation of the treatment, serum ICTP had returned to pretreatment values. We conclude that serum ICTP does reflect bone metabolism in po stmenopausal osteoporosis, but it is not a sensitive marker of the cha nges in bone resorption induced by hormone replacement therapy, and it does not correspond with other measures of bone resorption during ana bolic steroid therapy.