Serum Levels of Inflammatory Markers in Newly Diagnosed Hypothyroid Patients before and after Levothyroxine Therapy

Abstract

Introduction: Cytokines have a great significance in autoimmune thyroid disease. They are produced by thyroid follicular cells and have an indispensable role in T-cell and B-cell growth and differentiation. Tumour necrosis factor-alpha (TNF-α) is a cytokine having numerous immunological and metabolic activities and is an important stimulus for Interleukin-6 (IL-6) production. Interleukins play an important role in immune system function. Their deficiency causes autoimmune diseases or immune deficiency. Aim: To assess inflammatory markers IL-6 and TNF-α in hypothyroidism before and after attainment of euthyroid state by levothyroxine therapy and to find the correlation between serum levels of TNF-α and IL-6 in hypothyroid state. Materials and Methods: This quasi-experimental study was conducted in Department of Physiology at University College of Medical Sciences, New Delhi, India, from January 2013 to October 2013. Total 30 newly diagnosed hypothyroid patients of the age group 18-45 years formed case group and 30 age and sex-matched subjects formed the control group, were recruited for the study. The patients were given levothyroxine replacement therapy for three months. The inflammatory biomarkers level was evaluated using solid-phase sandwich Enzyme Linked Immunosorbent Assay (ELISA), using kits from Diaclone. Paired and Unpaired t-tests, respectively, were used for hypothyroid patients in pre-post state and between two groups at baseline. Serum Thyroid Stimulating Hormone (TSH) levels of hypothyroid patients were correlated with serum levels of inflammatory markers using Pearson’s correlation test. Results: There was no statistical difference in age, sex, Body Mass Index (BMI) and lipid profile in the two groups. Hypothyroidism subjects achieved euthyroidism in three months after obtaining levothyroxine therapy with the mean TSH levels 26.43±10.244 vs 3.4863±0.1963, mean free T3 levels 0.2980±0.9408 vs 1.93±0.5690 and mean free T4 levels 0.2736±0.0973 vs 1.8986±0.2853 in pre-post states, respectively. Serum levels of IL-6 and TNF-α were significantly higher (p-value <0.001) in hypothyroid subjects compared to euthyroid controls. A positive correlation between serum levels of IL-6 (r-value=0.5778, p-value=0.0008) and TNF-α (r-value=0.521, p-value=0.003) with serum TSH levels were found. Conclusion: The study reported a significant effect of levothyroxine therapy in restoring serum levels of raised inflammatory markers among hypothyroid patients. A decrease in low-grade chronic inflammation after treatment showed some clinical importance as chronic inflammation, is known to be associated with atherosclerosis and cardiac disease.

Keywords

• chronic inflammation
• interleukin 6
• thyroid stimulating hormone
• tumour necrosis factor-α