A Comparative Study of Serum Melatonin and TNF-α Levels in Patients with Thyroid Dysfunction

Abstract

Thyroid dysfunction, including hyperthyroidism and hypothyroidism, involve metabolic dysregulation, endocrine imbalance, and immune alterations. Cytokine signaling molecules such as TNF-α and regulatory hormones like melatonin may modulate pathogenic processes. Although autoimmune thyroiditis has been linked to elevated inflammatory markers, their diagnostic accuracy across broader thyroid dysfunction remains equivocal. This study aimed to assess serum melatonin and TNF-α levels among patients with thyroid dysfunction, and controls, and to assess their prospective utility as diagnostic indicators. The study involved 90 individuals, distributed proportionally into three groups including 30 hyperthyroidism, 30 hypothyroidism, and 30 controls group. Serum melatonin and TNF-α concentrations were quantified using enzyme-linked immunosorbent assay (ELISA). The results of serum melatonin concentrations were significantly elevated in both hyperthyroid (5.71 ± 0.84 ng/mL) and hypothyroid (5.57 ± 1.05 ng/mL) cohorts relative to controls (3.21 ± 0.31 ng/mL; P < 0.001), with no significant difference observed between the two patient groups. Receiver operating characteristic (ROC) analysis demonstrated acceptable diagnostic performance for distinguishing thyroid dysfunction from normal: hyperthyroidism, AUC = 0.761, sensitivity = 76.7%, specificity = 80.0%; hypothyroidism, AUC = 0.718, sensitivity = 73.3%, specificity = 70.0%. Mean serum TNF-α concentrations were elevated in hyperthyroid (23.56 ± 11.77 pg/mL) and hypothyroid (19.72 ± 12.05 pg/mL) patients compared with controls (15.15 ± 9.18 pg/mL), but the differences did not reach statistical significance (P = 0.101). Melatonin was significantly higher in both hyper- and hypothyroid patients, suggesting an adjunct biomarker for thyroid dysfunction. TNF-α showed a non-significant trend toward elevation, indicating potential inflammatory involvement that needs validation in larger studies.