[The effect of growth hormone therapy on thyroid parameters].

Abstract

Clinical observations and experimental studies indicate that administration of growth hormone (GH) affects thyroid parameters either via inhibited TSH secretion or via activation of the peripheral conversion of T4 to T3. For a period of six months after the onset of GH treatment basic thyroid parameters (TSH and total T3 and T4) were followed up in two groups of children: in 10 euthyroid girls with Turner's syndrome (TS) (age 6.2-11.3 years), hitherto not treated with GH and in six children (2 boys) with isolated idiopathic growth hormone deficiency (IGHD) (age 9.5-14.1 years). In the latter group GH treatment, 0.37 to 0.47 IU/kg/week for a period of 0.8 to 4.3 years preceded. This treatment was discontinued for 30 days before the investigation was started. During this treatment the condition was assessed as euthyroid without administration of L-thyroxine. Both groups of children were treated with GH administered by daily injection, girls with TS had a dose of 1 IU/kg/week, children with IGHD 0.42 IU/kg/week. In these girls with TS in the course of six months no change of the investigated parameters was recorded. In children with IGHD after three months' treatment a drop of T4 from (mean +/- SD) of 119 +/- 11 to 84 +/- 21 nmol/l (p = 0.01) occurred and a rise of the T3/T4 (x 100) index from 1.77 +/- 0.24 to 2.73 +/- 0.69 (p = 0.01) and of TSH from 1.1 +/- 0.7 to 2.2 +/- 0.6 mU/l (p = 0.005). The T3 level did not change. Within 6 months of treatment these changes receded completely and the levels returned to baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)