Thyrotropin-releasing hormone (TRH) induced a significant increase in plasma growth hormone (GH) levels in 4 of 8 children with primary hypothyroidism, while a slight decrease was observed in 8 control children. Base-line plasma prolactin (PRL) levels and peak responses to TRH were higher in hypothyroid children than in controls. These data may indicate the existence of dysfunction of central nervous system mechanisms of control of GH and PRL secretion in subjects with primary hypothyroidism.

t We found recently that these contaminants interfere little with the isonicotinic acid hydrazide reaction described reoen,tly by Weichselbaum and Margraf and which depends on the presence of a A4-3 ketone group (8).

Pimozide, a specific blocker of dopaminergic receptors, was administered orally to 10 adult male volumteers for 4 days. Half of the subjects received 4 mg/day and the other half 2 mg/day. Blood samples were obtained the day before, the 4th day of Pimozide, and 4 days after the last dose of the drug for the determination of LH, FSH, GH, PRL, TSH, cortisol and testosterone levels. Twenty-four h urinary collections were obtained for the determination of LH and FSH levels. Plasma LH levels decreased and plasma PRL levels increased in the combined groups during Pimozide. Plasma TSH levels decreased during treatment in the 4 mg group only. Urinary LH and plasma testosterone levels decreased in the post-treatment period in the combined groups. These data support the concept of a dopaminergic control of the secretion of several hormones in the human.

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