The effect of growth hormone (GH) therapy on urinary pyridinoline cross-links in GH-deficient adults

OBJECTIVE: The aim was to study the effect of growth hormone (GH) on new markers of bone resorption (fasting urinary excretion of pyridinium cross-links (pyridinoline and deoxypyridinoline)) in GH-deficient adults. DESIGN: Randomized, double-blind, placebo-controlled cross-over study. The treatment periods (GH 2 IU/m2 subcutaneously, or placebo daily for 4 months) were separated by a 4-month washout period. PATIENTS: Twenty GH-deficient adults (aged 18-39). MEASUREMENTS: Blood and fasting urine samples were collected at the end of each 4-month treatment period. Plasma bone Gla protein was measured by radioimmunoassay and urine pyridinoline and deoxypyridinoline were measured by spectrofluorometry after high performance liquid chromatography and corrected for urinary creatinine. RESULTS: GH increased fasting urinary excretion of pyridinoline (287 +/- 123%, P less than 0.001) and deoxypyridinoline (313 +/- 140%, P less than 0.001). The GH-induced increment in these parameters correlated with the increase seen in plasma bone Gla protein (r = 0.83-0.86, P less than 0.001). CONCLUSION: Four months of GH substitution in GH-deficient adults increases bone resorption as well as bone formation. The effect on bone mass has yet to be assessed.