# The Effect of Thyroid Function on GDF15 Levels

## TL;DR

This study explores how thyroid function affects GDF15 levels, finding that thyrotropin increases and free thyroxine decreases GDF15, with potential implications for metabolic stress.

## Contribution

The study provides new insights into the relationship between thyroid hormones and GDF15 levels in a large population cohort.

## Key findings

- Thyrotropin positively correlates with GDF15 levels after adjusting for covariates.
- Free thyroxine negatively correlates with GDF15 levels.
- Subjects with antibodies against thyroperoxidase have lower GDF15 levels.

## Abstract

Growth differentiation factor 15 (GDF15) is a stress-response cytokine, which exerts different actions in physiological and pathological conditions. Thyroid disorders are common in the general population and their role on GDF15 levels has not been sufficiently addressed. Serum levels of GDF-15 and thyroid function were assessed in a large sample from the SardiNIA cohort (n = 4413). We further collected antibodies against thyroperoxidase and anti-thyroglobulin in all participants. Thyroid function correlated with GDF15. Specifically, after adjusting for covariates, thyrotropin had a positive association with GDF15, while free thyroxine was negatively correlated. We also found that subjects with circulating antibodies against thyroperoxidase had lower GDF15 levels. The reduced level of the thyroid hormone can cause a decreased metabolic activity and higher cell stress response, which, in turn, increases the production of GDF-15 as a defense mechanism. The association between antibodies against thyroperoxidase and GDF15 deserves additional study to elucidate the pathophysiologic relationship.