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Changes in serum thyroxine, triiodothyronine, and thyrotropin induced by lithium in normal subjects and in rats
Author(s) -
Child Connie,
Nolan George,
Jubiz William
Publication year - 1976
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1976206715
Subject(s) - triiodothyronine , medicine , endocrinology , lithium (medication) , thyroid
Serum thyroxine (T4), triiodothyronine (T3), and thyrotropin (TSH) were measured in 4 normal subjects before, during, and 2 wk afler administration of lithium carbonate (1,200 mg/day) for 6 wk. All subjects developed thyroid enlargement associated with increase in TSH. Serum T3 and T4 did not change significantly. In 3 hypothyroid subjects maintained on thyroxine replacement, lithium administration did not alter circulating levels of T4 or T3, suggesting no effect of lithium on the extrathyroidal metabolism of the thyroid hormones. In ratsfed a low iodine diet containing 122 mg/kg/day lithium carbonate, goiter, increased 131 I uptake, and a decrease in intrathyroidal T3 and T4 with an increase in MIT, DIT, and MIT/DIT were observed at 3 wk. Serum T3 fell significantly only during the third week, while T4 did not change. Thyroid enlargement, secondary to a rise in TSH, appears to playa role in the adaptation of the thyroid gland to lithium carbonate. The exact mechanism for the elevation of TSH has not been elucidated.