Association of caspase-3 with thyroid hormone levels in patients with hypothyroidism – A hospital-based study

Introduction: This hospital-based prospective study examined the relationship between thyroid hormone levels and serum levels of caspase-3, a critical marker of apoptosis, in 183 patients diagnosed with hypothyroidism. Methods: Serum caspase-3 concentrations were measured using a human caspase-3 ELISA kit. Elevated caspase-3 levels indicate increased apoptotic activity. Results: In the overall cohort, the serum caspase-3 levels were not significantly correlated with the thyroid hormone level. However, among patients with mildly elevated TSH (Group I), caspase-3 levels were inversely correlated with T₃ (r = –0.319, p < 0.05) and T₄ (r = –0.377, p < 0.001). Age-stratified analysis revealed that among younger participants (18–40 years), age independently predicted lower caspase-3 levels (p = 0.027), suggesting a decline in apoptotic activity with advancing early adulthood. In older individuals (≥41 years), serum T₄ independently and negatively predicted caspase-3 levels (p = 0.048). Partial correlation analysis controlling for age rendered the previous associations non-significant, indicating that age was a confounding factor. Conclusion: The relationship between thyroid hormones and apoptosis appears to be both age- and severity-dependent. While thyroid hormones are inversely associated with apoptotic activity in mild hypothyroidism, age independently influences caspase-3 in younger individuals and T₄ remains a significant predictor in older adults. These findings underscore the complex interplay between aging, thyroid function, and apoptosis, with implications for thyroid-related pathophysiology across the lifespan.