The effect of prolonged lithium carbonate administration on the thyrotrophin and prolactin response to thyrotrophin-releasing hormone.
Thyrotrophin (TSH) and prolactin (PRL) responses to intravenous thyrotrophin-releasing hormone (TRH) were measured in euthyroid patients suffering from psychiatric disease on long-term lithium carbonate (LC) and phenothiazine therapy. These responses were retested after oral tri-iodothyronine (T3) 120 mug/day had been given for a week. The raised basal TSH and the suppression of the exaggerated responses to TRH by T3 found in some of the patients suggest a mild disturbance of thyroid function in patients on long-term LC therapy, even in the face of clinical euthyroidism and otherwise normal thyroid function. Basal serum PRL levels and the responses to TRH were elevated in 2 of 5 patients, probably associated with phenothiazine administration. In all 5, a moderate blunting of the PRL responses after TRH was produced by T3. The suppressive effect of T3 on TRH-induced PRL responses was unexpected and suggests a modifying role of thyroid hormones on PRL secretion, although further studies are needed to confirm this possibility.
D005260:Female; D006801:Humans; D008094:Lithium / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010640:Phenothiazines / Q000494:pharmacology; D011388:Prolactin / Q000097:blood* / Q000378:metabolism; D013268:Stimulation, Chemical; D013972:Thyrotropin / Q000097:blood* / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014284:Triiodothyronine / Q000494:pharmacology
D010640:Phenothiazines; D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D013972:Thyrotropin; D008094:Lithium