Premium
VITAMIN D METABOLISM IN HYPERTHYROIDISM
Author(s) -
MACFARLANE I. A.,
MAWER E. B.,
BERRY J.,
HANN J.
Publication year - 1982
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1982.tb02633.x
Subject(s) - medicine , endocrinology , chemistry , triiodothyronine , calcifediol , vitamin d and neurology , metabolism , calcitriol , parathyroid hormone , bone remodeling , hypoparathyroidism , calcium , hormone
SUMMARY The serum concentrations of 25‐hydroxycholecalciferol (25 OH D 3 ), 24,25‐dihydroxycholecalciferol [24,25(OH) 2 D 3 ] and 1,25‐dihydroxycholecalciferol [1,25(OH) 2 D 3 ] were measured in twenty‐one patients with untreated hyperthyroidism. Compared with control subjects, 25 OH D 3 concentrations were not altered, 24,25(OH) 2 D 3 concentrations were increased, although not significantly and 1,25(OH) 2 D 3 concentrations were decreased ( P = 0.01). Following oral carbimazole therapy, 24,25(OH) 2 D 3 concentrations fell ( P <0.01), 1,25(OH) 2 D 3 concentrations increased ( P <0.01) and 25 OH D 3 concentrations were unchanged. The altered 1,25(OH) 2 D 3 and 24,25(OH) 2 D 3 concentrations found in hyperthyroidism are probably due to the effects of thyroid hormone on bone and mineral metabolism. Increased serum calcium and phosphate concentrations with secondary hypoparathyroidism result in stimulation of the renal 24‐hydroxylase and suppression of the 1‐hydroxylase enzymes. In addition, serum 24,25(OH) 2 D 3 concentrations were significantly correlated with serum triiodothyronine levels (T3) ( r = 0.66, P <0.002) before treatment. This may indicate a direct stimulatory effect of T3 on 24‐hydroxylase activity. No relationship was found between serum 1,25(OH) 2 D 3 concentrations before therapy and serum T3.