INCREASE IN BONE-DENSITY AND PLASMA OSTEOCALCIN DURING GROWTH-HORMONETHERAPY IN GROWTH-HORMONE DEFICIENT CHILDREN

Bone density in growth hormone (GH) deficient children is decreased mo re than expected for delayed skeletal maturation. Previous studies sug gest GH enhances mineral retention and deposition in bone. Seven GH de ficient prepubertal children were studied during 2 years of GH therapy to assess the effect on bone density and plasma osteocalcin. Bone den sity (radiographic photodensitometry) of the phalanges (cortical and t rabecular bone) was expressed as the standard deviation score (SDS) of the mean for sex, bone age and chronological age. Relative osteopenia , less pronounced for bone density/bone age (BD/BA) than bone density/ chronological age (BD/CA), improved significantly during GH therapy. After 12 months there was increase over pretreatment levels, significa nt for BD/CA (-1.65 +/- 0.46 vs -1.15 +/- 0.64; mean +/- SD: p = 0.002 ), but less pronounced for BD/BA. After 24 months increase in both mea surements continued, reaching significance also for BD/BA (Pre: -1.02 +/- 0.55 vs -0.41 +/- 0.29; p = 0.011). Plasma osteocalcin levels were low before GH therapy (11.6 +/- 9.9 ng/ml; n = 7; vs control 24.4 +/- 12.5 ng/ml; n = 21; p < 0.05), rose significantly after one week (31. 2 +/- 10.5 ng/ml; p < 0.001), with continued upward trend to plateau b etween 2-6 months, with elevated levels persisting during 2 years of G H therapy. Conclusion: The early and sustained rise in plasma osteocal cin and subsequent increase in bone density with continued gain over 2 4 months of the study suggests that GH therapy in GH deficient childre n has a significant prolonged effect on bone formation and mineralizat ion in addition to stimulating linear growth.