Dynamic and structural properties of the skeleton in hypoparathyroidism

Hypoparathyroidism, a disorder in which PTH is absent, is associated with BMD that is above average. We studied associated structural and dynamic properties of the skeleton in hypoparathyroidism. Thirty-three subjects with hypoparathyroidism and 33 age- and sex-matched control subjects with no known metabolic diseases underwent percutaneous iliac crest bone biopsies after double-labeling with tetracycline. The main outcome was histomorphometric assessment of structural and dynamic skeletal parameters. Subjects with hypoparathyroidism had greater cancellous bone volume (mean ± SD; BV/TV: 23.5 ± 8 versus 19.7 ± 5%, p = 0.02), trabecular width (Tb.Wi: 136.1 ± 37 versus 119.3 ± 21 μm, p = 0.03), and cortical width (Ct.Wi: 923.4 ± 420 versus 753.5 ± 246 μm, p = 0.05) than control subjects. Dynamic skeletal indices, including mineralizing surface (MS: 0.85 ± 1.58 versus 4.27 ± 3.32%, p < 0.0001) and bone formation rate (BFR/BS: 0.006 ± 0.014 versus 0.032 ± 0.028 μm ³/μm²/d, p < 0.0001), were profoundly suppressed in the hypoparathyroid subjects. We conclude that hypoparathyroidism is characterized by markedly unusual structural and dynamic properties of bone.