Human Lactational Response to Oral Thyrotropin Releasing Hormone

Abstract

Several studies were designed to evaluate the effect of oral TRH on prolactin (PRL) secretion and mammary function in nursing women. Initially, efficacy was studied in nursing women following 5 mg TRH. PRL levels rose to a mean maximum of 46.3 ng/ml above baseline at 60 min. Plasma TSH also incresed from a mean baseline of 2.6 to 17.6 muU/ml at 180 min. No changes were observed following placebo. In order to observe the long term effects of oral TRH, two groups of women in full nursing were studied. Beginning on day 29 postpartum, either 5 mg TRH or placebo were taken twice daily for four weeks. No chronic elevations were observed in maternal PRL and TSH or in infant TSH before or after one month of either regimen. Milk composition expressed in terms of per cent protein and per cent fat did not differ between the groups. Weekly gonadotropin levels were also similar as were infant weight gain and growth. In a group of women with lactational insufficiency receiving 5-20 mg TRH twice daily for five days, basal PRL concentrations markedly increased. While changes in milk composition were not significant, fat percentages increased slightly and protein percentages declined. Breast engorgement and milk letdown increased and full nursing was restored. While the oral TRH used in fully nursing women had no demonstrable effect on mammary function, it may prove useful in those women with lactational insufficiency. Because two women developed iatrogenic hyperthyroidism following 40 mg oral TRH twice daily, care must be exercised in determining the dosage to be employed.

Safety and Efficacy of Galactogogues: Substances that Induce, Maintain and Increase Breast Milk Production

“…Milk volume and composition remained the same in the two groups (71). This was confirmed with another study carried out in full nursing women treated either oral TRH (5 mg, 2 times a day, for 4 weeks) or a placebo (70). On the other hand, in a group of women with lactational insufficiency receiving 5-20 mg TRH twice daily for 5 days, basal PRL concentrations markedly increased, breast engorgement and milk letdown increased and full nursing was restored.…”

“…Mechanism of action: TRH stimulates the secretion of TSH and PRL by the pituitary gland (37,(69)(70)(71).…”

“…This drug can also be given intravenously (200 μg) (74) or orally 5-20 mg 2-3 times/day for a period ranging from 5 days to 4 weeks (69)(70)(71)(72).…”

Pharmacological Overview of Galactogogues

“…Women treated with synthetic TRH 20 mg PO three times a day had high blood concentrations of PRL [105]. In another study, TRH administration for one month, at doses of 5 mg twice a day PO, did not change PRL blood concentration in human [106]. TRH has been effective in the induction of lactation in mothers with agalactia 10–150 days after birth [107], but its galactogogue effect is variable [108].…”

Increase of Serum Thyrotropin (TSH) of Suckling Rats after Thyroliberin (TRH) Injection to Lactating Mothers

“…Recent papers claim that prolonged treat ment of lactating women with TRH was not followed by the abnormal TSH and thyroxine values in their suckling infants (13,14). The comparison of weaned and suckling infants showed, however, higher serum TSH in the latter, although all parameters (including TSH) were normal (10).…”