Bone mineralization and calciotropic hormones in children with hyperthyroidism. Effects of methimazole therapy.
We studied bone mineralization and calcium homeostasis in two children with hyperthyroidism before and during 3 yr of methimazole therapy in order to evaluate the effects of thyrotoxicosis and its therapy on mineral metabolism. Case 1, female, 4.1 year old with hyperthyroidism from 6 months. Biochemical data: increased thyroid function, phosphate and osteocalcin, decreased 1,25(OH)2D levels. X-ray: severe osteoporosis; bone mineral content (BMC) -23.0%, BMC/BW -25.1%. Case 2, female, 7.4 year old with hyperthyroidism from 9 months. Biochemical data: thyroid function, ionized calcium and osteocalcin were increased, 1,25(OH)2D and intact PTH were decreased. X-ray: severe osteoporosis: BMC -32.8%, BMC/BW -36.0. After the patients were euthyroid, they showed an increase of 1,25(OH)2D and intact PTH into normal values and a fall in calcium and phosphate. Osteocalcin levels returned in normal range one yr after first evaluation. Bone mineral analysis showed no variation of BMC and BMC/BW in the first 6 months of therapy and an increase in the following 6 months. In the following two years BMC and BMC/BW rose to normal range. Our study provides further evidence that in hyperthyroidism an altered mineral homeostasis is present with a reversible disturbance in vitamin D metabolism. We found that the return to euthyroidism was associated with a normalization of mineral homeostasis and with a recovery of bone mineralization. Osteocalcin assay may be an useful index to monitor bone metabolism in hyperthyroidism.
Saggese
G
G
Istituto di Clinica Pediatrica, Università di Pisa, Italy.
Bertelloni
S
S
Baroncelli
G I
GI
D015502:Absorptiometry, Photon; D015519:Bone Density / Q000187:drug effects / Q000502:physiology; D001842:Bone and Bones / Q000378:metabolism; D002113:Calcification, Physiologic / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006980:Hyperthyroidism / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D008713:Methimazole / Q000627:therapeutic use; D008903:Minerals / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism*; D011863:Radioimmunoassay
D008903:Minerals; D015675:Osteocalcin; D008713:Methimazole; D002118:Calcium