Authors’ Response: Cortical Bone Density Is Normal in Prepubertal Children with Growth Hormone (GH) Deficiency, but Initially Decreases during GH Replacement due to Early Bone Remodeling

Abstract

Dual energy x-ray absorptiometry (DEXA) has revealed that GH- deficient adults gain in bone mineral density during GH therapy. Measurements of volumetric bone density (grams per cubic centimeter vs. grams per square centimeter) and structure, however, are achieved through peripheral quantitative computed tomography (pQCT). In 45 prepubertal GH-deficient children, we studied pQCT measurements before the start and for 12 months of GH treatment. Serum alkaline phosphatase (AP), procollagen I carboxyl-terminal propeptide (PICP), and deoxypyridinoline reflected bone metabolism status. Findings at the start of GH treatment were (mean sd score): bone area, −0.44; cortical density, −0.03; cortical area, −1.32; cortical thickness, −1.41; and marrow area, +0.66. At 12 months, cortical density had fallen to −0.73 (P < 0.001), whereas cortical area and thickness, and marrow area did not change. AP, PICP, and deoxypyridinoline increased significantly within the first 3 months (increase: AP, 66.5 U/liter; PICP, 72 μg/l...