Thyroid and Growth Hormones Interdependence: A “Reciprocal Potentiation”, the Synergy for Growth and Development at Childhood

Abstract

Aims: To investigate the effect of variations of plasma levels of thyroid and growth hormones on the physical growth indexes, the variation of these hormones with age, correlation of thyroid and growth hormones at varying concentrations of growth hormone in children aged 6-10 years. Study Designed: Department of Medical Laboratory Science, University of Calabar, conducted between March 2014 and February 2015. Methodology: Anthropometric uniqueness were described and Body Mass Index calculated for 180 (male 81 and female 99) participants of the study. Thyroid and growth hormones were determined by Enzyme-Linked Immunosorbent Assay (ELISA) specific for the various hormones, using STAT FAX 303 microtitre plate reader. Results: Nineteen percent (n=34) had GH values (≤0.6 ng/ml), lower than the expected normal, 64% (n=115) had values between (0.6-10.0ng/ml) while 17% (n=31) had values ≥10.0 ng/ml. Ninety two percent (n=166) of the children had thyroid stimulating hormone (TSH) values between 0.35-8.44 µIu/ml; 6.1% (n=11) had values >8.44 µIu/ml which are above normal while1.7% (n=3) had values <0.35 µIu/ml lower than normal. Triiodothyronine appears to increase from birth recording a peak within the first year of postnatal life, and then progressively declining to adult values while GH increases from birth attaining a peak about the age of nine then falling progressively to adult values. Children with apparent GH deficiency had significantly higher T3 and T4 levels and lower TSH, those with high GH values had correspondingly low T3 and T4 values and high TSH. The correlation coefficients of TSH and growth hormones in those with high and low GH (r=-0.05 and r=-0.130) respectively were both negative while that of TSH and GH in those with normal GH was positive (r=0.093), however, physical growth indexes are preserved across board. Conclusion: It was concluded from the study that growth failure may be due to failure of both hormones and may likely not occur when an unbroken synergy exist between thyroid and growth hormones during childhood.