Effects of Corticotropin Releasing Factor and Growth Hormone Releasing Factor on Pituitary Hormone Secretion in Patients with Congenital Thyrotropin Deficiency.

Summary

Blood concentrations of anterior pituitary hormones, ACTH, GH, TSH, PRL, LH, and FSH were determined in Corticotropin releasing factor (CRF) test (synthetic ovine CRF 1.0 μg per kg body weight) and growth hormone releasing factor (GRF) test (synthetic human pancreatic GRF-44 100 μg) in 2 female sibling patients with congenital isolated TSH deficiency, in their mother, in 2 patients with congenital primary hypothyroidism and in 8 normal controls.

The patients with isolated TSH deficiency showed normally increased plasma ACTH and serum GH after CRF and GRF, respectively, and also showed an abnormal GH response to CRF. The serum GH showed a rapid increase to maximum levels (12.9 ng/ml) within 30 to 60 min followed by decrease. The possibility of secretion of abnormal GH could be excluded by the fact that on serum dilution, GH value gave a linear plot passing through zero. In addition, serum PRL, LH and FSH levels after CRF administration in case 1 and PRL after GRF in case 2 were also slightly increased but these responses were marginal. The mother of the patients, patients with congenital primary hypothyroidism, and normal healthy controls showed normal responses of pituitary hormones throughout the experiment.

Data from the present study and a previous report show that abnormal GH response to the hypothalamic hormones (CRF, TRH and LHRH) may be observed in patients with congenital isolated TSH deficiency.

Key-Words

Isolated TSH Deficiency - CRF - GRF - Abnormal GH Response