Gonadotropin and growth hormone nocturnal secretion rhythms in hypothyroid children

Plasma FSH,LH and GH nocturnal rhythms were studied in 5 untreated hypothyroid children, aged 10 months to 14 years. Blood samples were obtained at 30 minute intervals between 10p.m. and 8a.m. The results of this study indicate that there is no increased gonadotropin secretion in untreated primary hypothyroidism. The plasma gonadotropin levels, determined by radioimmunoassay were consistent with those expected for the patients' ages. This observation, however, can not explain the occurence of premature puberty on certain patients with hypothyroidism. Further studies are indicated to clarify the mechanism of this phenomenon. Normal GH secretion rhythms were observed on these patients with primary hypothyroidism. It is, therefore, concluded that the secretion rhythms of gonadotropins, as well as of growth hormone remain normal in this disorder.