Prolactin and thyroid status in prepubertal children with mild to moderate obesity

Prolactin (PRL) response to thyrotropin releasing hormone (TRH) in 21 prepubertal children with mild to moderate obesity was compared with that in 21 normal prepubertal children (controls). Basal PRL levels were normal but the mean peak PRL response and mean increment in PRL levels following TRH administration were significantly lower in prepubertal obese children (p less than 0.001). The mean PRL responses to TRH were significantly impaired at all time intervals in prepubertal obese boys and girls compared to the control subjects. Linear regression and correlation coefficient analysis did not reveal any significant relation between the percent overweight and PRL response. Basal T4, T3 levels and T3 and TSH response to TRH were similar in both groups. The findings suggest that neuroendocrine regulation of prolactin is impaired in prepubertal children even with mild to moderate obesity. This could be secondary to altered neurotransmitter status at the hypothalamic level. Further studies are needed to determine whether the defect is innate or acquired, primary or secondary.