Acute and early effects of triiodothyronine administration on serum markers of bone and mineral metabolism.

There have been few studies on acute changes of bone metabolism in humans by thyroid hormone. This study aimed to examine the effects of triiodothyronine on serum markers of bone and mineral metabolism during a 7-d course of daily 75 microg therapy in 14 normal volunteers by drawing blood on 1, 2, 3, 5, and 7 d of therapy. Serum calcium concentrations did not significantly change during the course of therapy, while serum phosphorus concentrations were significantly (p < 0.05) decreased from 3.21 +/- 0.43 mg/dL (mean +/- SD) to 2.85 +/- 0.46 mg/dL on the 7th d. Serum PTH concentrations were significantly decreased from 339 +/- 116 pg/mL to 316 +/- 29 pg/mL. Serum concentrations of alkali-phosphatase and bone-specific alkali-phosphatase were not significantly changed, but serum osteocalcin concentrations were significantly increased from 5.71 +/- 1.98 mg/dL to 6.73 +/- 2.24 mg/dL. Serum carboxy-terminal propeptide of type I collagen concentrations were significantly decreased from 137.8 +/- 33.7 microg/L to 119.2 +/- 33.6 microg/L. Serum pyridinoline cross-linked telopeptide domain of type I collagen concentrations, a bone resorption marker, were significantly increased from 3.40 +/- 0.77 to 3.87 +/- 1.05 microg/L, and such significant increase was obtained from the 3rd day. The results indicate that some of bone and mineral markers change rapidly in response to triiodothyronine-induced acute thyrotoxicosis, but the manner of change is not the same as that of chronic thyrotoxicosis.

Body height and weight of patients with childhood onset and adult onset thyrotoxicosis.

The present study has compared body height and weight of thyrotoxic female patients of childhood onset and adult onset. The body height of 141 out of 143 (99%) adult-onset thyrotoxic patients was within the range of mean +/- 2SD for the age-matched general Japanese female population. On the other hand, in 42 patients with childhood-onset thyrotoxicosis, 6 (14%) had their height being greater than the mean + 2SD of general population, and 34 (81%) were taller than the mean value. In 86 patients with siblings, 42 (49%) were at least 2 cm taller than their sisters, and 26 (30%) were more than 2 cm shorter than their sisters. The body weight of 27 out of 42 (68%) patients younger than 20 years was not decreased but was even greater than the mean value for the age-matched general population. The results indicate that excessive thyroid hormone in vivo enhances body height in humans. The increased body weight in some young patients suggests that enhanced dietary intake due to increased appetite in hyperthyroidism has overcome the energy loss with increased metabolism.