[Bone involvement in hypothyroidism in adults. Apropos of 20 patients]

Although bone changes in hyperthyroidism are well known, they have been much less studied in hypothyroidism and we set out to establish whether they did occur in the latter condition. We present the results of a prospective study of 20 adult patients, with acquired primary hypothyroidism. No changes in urinary or blood calcium or phosphorus metabolism were observed and serum parathormone, 25-hydro, 125-dihydro and 24-25-dihydroxycholecalciferol concentrations were normal. Histological examination of iliac crest bone biopsy after double labelling with tetracycline showed normal bone trabeculation volume, surface of resorption and rates of calcification. However, the relative osteoid volume was increased and there was a much higher osteoid thickness index. These observations may be explained by a global decrease in the activation and activity of the multicellular units of bone remodeling due to the general slowing of cellular metabolism encountered in that condition.