Persistent pituitary resistance to thyroid hormone in congenital versus later-onset hypothyroidism

J Endocrinol Invest. 1985 Dec;8(6):527-32. doi: 10.1007/BF03348554.

Abstract

The pituitary and peripheral responses to L-T4 and L-T3 therapy were studied in 12 patients with congenital goitrous hypothyroidism, in 10 patients with an ectopic thyroid and onset of hypothyroidism at 3-8 years of age, and in 6 patients with adult-onset hypothyroidism, after they had had their chronic thyroid hormone replacement therapy discontinued for 30 days. They were first treated with increasing L-T4 (0.1, 0.2 and 0.4 mg daily) followed by L-T3 (0.05 and 0.2 mg daily) after stopping thyroid medication for another month. Ten normal subjects were treated identically. In normal individuals the peak TSH, alpha, and TSH-beta response to TRH was significantly decreased with 0.1 mg L-T4 or 0.05 mg L-T3 daily and was suppressed with 0.2 and 0.4 mg L-T4 or 0.2 mg L-T3 daily; serum cholesterol and triglyceride decreased significantly with 0.2 or 0.4 mg L-T4 or 0.2 mg L-T3 daily; testosterone-estradiol binding globulin (TeBG) increased significantly at the same doses. In congenitally hypothyroid patients receiving 0.2 mg L-T4 daily, the mean peak TSH after TRH was 24 +/- 17 microU/ml, whereas in patients with an ectopic thyroid or adult-onset hypothyroidism the peak TSH was significantly less at 5.9 +/- 8.8 and 5.5 +/- 5.7 microU/ml, respectively. Only at the highest doses of L-T4 (0.4 mg/day) or L-T3 (0.2 mg/day) was the TSH response to TRH suppressed in the congenitally hypothyroid group. The alpha and TSH-beta subunit levels followed those of TSH.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Cholesterol / blood
  • Congenital Hypothyroidism
  • Drug Resistance
  • Female
  • Humans
  • Hypothyroidism / blood
  • Hypothyroidism / drug therapy*
  • Male
  • Pituitary Gland / drug effects*
  • Sex Hormone-Binding Globulin / metabolism
  • Thyroid Hormones / therapeutic use*
  • Thyrotropin / blood
  • Thyrotropin-Releasing Hormone
  • Thyroxine / therapeutic use
  • Triglycerides / blood
  • Triiodothyronine / therapeutic use

Substances

  • Sex Hormone-Binding Globulin
  • Thyroid Hormones
  • Triglycerides
  • Triiodothyronine
  • Thyrotropin-Releasing Hormone
  • Thyrotropin
  • Cholesterol
  • Thyroxine