Effect of Severe Protein-Energy Malnutrition on Circulating Thyroid Hormones

Abstract

Protein energy malnutrition (PEM) is one of the most common health problems among Bangladeshi children. PEM is known to induce a wide variety of metabolic disorders and some of which may be mediated through alteration of endocrine functions. Both short-term and long-term alterations in nutritional state affect various aspects of thyroid hormone economy, especially peripheral hormone metabolism. Chronic malnutrition is associated with a decreased serum T₃ concentration. Serum T₄ levels also tend to be slightly decreased because of a modest decrease in iodothyronine binding protein. TSH concentrations and their response to exogenous TRH are usually normal. To identify the effects of severe protein energy malnutrition on circulating iodothyronines especially circulating T₃ & T₄ and to determine the level of TSH in severe PEM. To compare the levels of thyroid hormones before and after recovery from severe PEM and to identify any correlation with mortality and morbidity. A prospective cross-sectional comparative study was performed in Nutrition block, Department of Pediatrics, Chittagong Medical College Hospital from 01 Dec 2007 to 30 Nov 2008. Patient admitted to nutrition block with severe PEM were included in the study. The levels of T₄, T₃ and TSH measured by radioimmunoassay (RIA) method. TSH was measured by using Immunoradiometric Assay Kit, IMK-432 produced by Beijing Atom Hitech Co. Ltd, China. T₃ and T₄ were measured by using Radioimmunoassay Kit (PR), IMK-422 and IMK-419 respectively produced by Beijing Atom Hitech Co. Ltd, China. Data were presented as the percentage of total number of observation. SPSS- Version 15.0 was used for the analysis of data. Student’s t-test, Z-test, χ-square test and Pearson’s correlation test were used for statistical significance. ‘p’ value of < 0.05 were used as the  minimum level of significance. The effect of protein energy malnutrition (PEM) in the children on serum levels of total thyroxine (TT₄), total triiodothyronine (TT₃) and thyrotropin (TSH) were evaluated. There were 50 children aged 6 to 60 months in the malnutrition group and 22 healthy age and sex matched controls. Serum TT₄ and TT₃ were all reduced in the malnutrition group. This decrease in TT₃ was more significant (p<0.001) in severe malnutrition than in mild PEM. Serum TSH levels in the malnutrition and control groups were similar. These results suggest that the children remained euthyroid and represent an adaptive response to protein energy malnutrition. The results of the above mentioned studies clearly demonstrate that thyroid functions are adversely affected in severe PEM. This was evidenced by reductions in T₃ & T₄ levels in comparison to control group.

Keywords: Protein Energy Malnutrition; Thyroxine; Triiodothyronine; Thyrotropin.