Abstract
Brain and somatic growth are retarded by both experimental hyper- and hypothyroidism in the developing rat. Because of increasing use of thyroid replacement therapy in the human neonate we studied the effects of abnormal thyroid states on rGH during the neonatal period.
Litters of newborn rat pups were injected daily from ages 0-19 days with thyroxine (T4), 0.4 μg/gram of body weight, while littermate controls were injected daily with saline. Other litters were rendered hypothyroid by injection of the mothers with 50 mg. propylthiouracil (PTU) daily from 18 days gestation via intragastric gavage. Controls received an equal volume of saline.
In both experimental groups, the developmental curve for rGH in controls as measured by radioimmunoassay fell from 120 ng/ml on day one to 10 ng/ml on day 19. Both thyroxine and PTU treated pups showed a consistent depression in rGH levels at each age of early development. The maximum deficit in T4 animals was 6% of control at day 18, and in PTU animals, was 14% of control at day 15. Individual data points for treated and control animals were log transformed, following which the developmental profiles were analyzed by a one way analysis of covariance. Both hyper- and hypothyroid pups showed a statistically significant deficiency of rGH throughout early development. The early suppression in both conditions suggests the necessity for careful titration of thyroid replacement therapy in human congenital hypothyroidism.
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Poland, R., Weichsel, M. 325 EFFECT OF HYPER- AND HYPOTHYROIDISM ON SERUM GROWTH HORMONE (rGH) IN THE DEVELOPING RAT. Pediatr Res 12 (Suppl 4), 418 (1978). https://doi.org/10.1203/00006450-197804001-00330
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DOI: https://doi.org/10.1203/00006450-197804001-00330