Ghrelin and obestatin in thyroid dysfunction

Abstract

Introduction: Ghrelin and obestatin derive from the same precursor. Ghrelin is an energy balance regulator and obestatin's role in metabolic processes cannot be excluded. The aim of this study was to assess plasma ghrelin and obestatin changes in thyroid disorders.

Material and methods: We evaluated plasma ghrelin and obestatin levels in severe hypothyroidism, hypothyroidism after thyreoidectomy and 4-weeks L-thyroxine withdrawal, and in hyperthyroidism. We also re-evaluated plasma ghrelin and obestatin levels in patients with severe hypothyroidism and hyperthyroidism after treatment.

Results: Severe hypothyroidism was associated with a reasonably high ghrelin level (p = 0.055) and hyperthyroidism with a significantly lower ghrelin level (p = 0.01) compared to healthy subjects. Ghrelin in hypothyroid patients after L-thyroxine withdrawal did not differ from the control group (p = 0.3). Compared to healthy subjects, obestatin level in hyperthyroidism was decreased (p = 0.03) and did not differ in severe hypothyroidism due to thyroiditis (p = 1) or after L-thyroxine withdrawal (p = 0.6). Ghrelin and obestatin levels correlated positively. Both peptides levels correlated positively with TSH and negatively with free thyroid hormones. In patients with severe hypothyroidism, ghrelin level significantly decreased after treatment (p 〈 0.01) and in hyperthyroid patients significantly increased after treatment (p = 0.04). There were no significant changes in obestatin levels in hypo- or hyperthyroid patients after treatment.

Conclusions: Plasma ghrelin changes and its correlation with TSH and thyroid hormones may indicate a compensatory role of ghrelin in metabolic disturbances associated with thyroid dysfunction. The positive correlation between ghrelin and obestatin levels may suggest a modulatory role of obestatin in these processes.