Multiple abnormalities of anterior pituitary hormone secretion in association with pseudohypoparathyroidism

A male with pseudohypoparathyroidism presented with several hormonal abnormalities. He was clinically euthyroid with no palpable goiter, His serum T4, total T3, T3 Sephadex retention, and 131I uptake were normal. However, elevated basal TSH levels and exaggerated TSH responses to TRH which normalized during the administration of thyroid extract suggested reduced thyroidal reserve. Despite these finding the 131I uptake increased after exogeneous TSH, and the T3 level rose after TRH. Basal testosterone levels and response to hCG were normal however, gonadotropins were elevated and there was an exaggerated response after LRH treatment. Both LH and FSH levels were suppressed by testosterone propionate. The patient demonstrated intermittent basal hyperprolactinemia and impaired PRL responsiveness after metolopramide, chlorpromazine, and insulin administration. There was, however, an intact response to TRH. Basal PRL, TSH, and LH levels decreased after the administration of L-dopa and bromocriptine. Although the precise mechanism underlying these finding is unknown, the elevated basal levels of TSH, LH, and FSH and the exaggerated responses to their respective releasing hormones suggest the presence of partial degree of end-organ resistance to these pituitary trophic hormones. Together with the resistance to PTH, this may imply a common defect, presumably at a postreceptor level. However, hyporesponsiveness of PRL to metoclopramide and chlorpromazine and normal responsiveness to TRH suggest that an abnormality of dopamine tone also exists in pseudohypoparathyroidism.