Investigating the relationship between irisin and cortisol levels in thyroid disease patients

Background: Both thyroid hormones and irisin have profound influences on the metabolism of the human body. Based on their similarities, several studies have been conducted to explore changes in irisin levels in patients with hypothyroidism and hyperthyroidism. Thyroid dysfunction has been reported in hypercortisolism.

Aims: The study aimed to investigate the association between thyroid function and cortisol and to explore the possible interchangeable metabolic roles between irisin and thyroid hormones.

Methods: The studied group consisted of 100 patients in which patients with thyroid dysfunction were formed in two groups as hypothyroid group and hyperthyroid group according to their thyroid hormones' levels and compared to healthy control group. Venous blood samples were analyzed for irisin, thyrotropin (TSH), thyroxine (T4), triiodothyronine (T3) and cortisol serum concentrations by using enzyme linked immunosorbent technique.

Results: The current study showed a significant increase (P < 0.001) in the serum level of cortisol in hyperthyroid group (52.36 ± 32.11 mcg/dL) compared to hypothyroid (27.04 ± 20 mcg/dL) and euthyroid group (24.09 ± 3.30 mcg/dL). The serum level of irisin in hyperthyroid group is significantly higher (P < 0.001) than that of hypothyroid group, however there is no significant difference between serum level of irisin in hyperthyroid group and that in the euthyroid group.

There is a significant positive correlation between serum level of both T3 and T4 with both irisin and cortisol in patient group. Also there is a significant negative correlation between serum level of TSH and both irisin and cortisol in patient group. However, these correlations were not established in the control subjects.

Conclusion: The current study demonstrates that irisin and cortisol concentrations may vary according to the thyrometabolic state. Through the exploration of this issue on group of patients with thyroid dysfunction and healthy subjects, a potentially deeper insight into these significant and evolutionary conserved regulatory mechanisms may be achieved.