iodothyronine, Thyrotropin, and Free Thyroxine, David Zurakowski, James Di Canzio, and Joseph A. Majzoub ( Departments of Biostatistics and Medicine and 2 Division of Endocrinology, Department of Medicine, Children’s Hospital, Harvard Medical School, Boston, MA 02115; * address correspondence to this author at: Department of Biostatistics, Children’s Hospital, 300 Longwood Ave., Boston, MA 0211...

Subclinical hyperthyroidism may be defined as the presence of free thyroxine and tri-iodothyronine levels within the reference range and a reduced serum thyroid stimulating hormone (TSH) level. In this review the prevalence of low TSH in the population and health consequences of subclinical hyperthyroidism, for example, effects on heart and bone mass, are discussed. Guidelines for treatment are...

In all classes of vertebrates, the deiodination of the prohormone T(4) to T(3) represents an essential activation step in thyroid hormone action. The possible presence of iodothyronine deiodinase activity in protochordates has been demonstrated in vivo. Recent molecular cloning of the genomes and transcripts of several ascidian species allows further investigation into thyroid-related processes...

The role of the deiodinases D1, D2, and D3 in the tissue-specific and time-dependent regulation of thyroid hormone bioactivity during fetal development has been investigated in animals but little is known about the ontogeny of these enzymes in humans. We analyzed D1, D2, and D3 activities in liver microsomes from 10 fetuses of 15-20 weeks gestation and from 8 apparently healthy adult tissue tra...

We have shown that protein restriction during lactation is associated with higher levels of serum and milk tri-iodothyronine (T(3)) with lower serum thyroxine (T(4)), suggesting an increased T(4) to T(3) conversion. To investigate this hypothesis, the activity of type 1 (D1) and/or type 2 (D2) iodothyronine deiodinases was evaluated on days 4, 12 and 21 of lactation in several tIssues of dams f...