The Effect of Carboxyhemoglobin Concentration on Thyroid Hormones in Carbon Monoxide Poisoning

Objective: Carbon monoxide (CO) poisoning is frequently seen in emergency departments and can cause many negative clinical effects. One of these is hormonal effects. This study aimed to evaluate the relationship between plasma carboxyhemoglobin (COHb) levels and late-stage thyroid hormones. Methods: This retrospective study was performed in the Emergency Department of Bağcılar Training and Research Hospital, including 329 patients aged 18 and older who presented with CO poisoning from January 2010 to January 2019. The severity of poisoning was classified based on COHb levels. The relationships among changes in thyroid hormone levels, carboxyhemoglobin (COHb) levels, and mortality data were assessed. Results: The mean values for TSH were 3.61 (2.6-4.38) U/L, T3 were 3.7 (3.1-4.2) pmol/L, and T4 were 1.44 (1.29- 1.63) ng/dL, with significantly elevated levels observed in the severe poisoning group (P < .001). The univariate Cox analysis conducted based on changes in thyroid hormones, age, glucose level, serum COHb, TSH, T3-2, and T4 resulted in significant results. In the multiple Cox analysis, age, serum COHb, and T4 emerged as predictive factors. Conclusion: Carboxyhemoglobin levels and the severity of poisoning may serve as significant indicators for estimating late-stage thyroid hormone levels in cases of carbon monoxide poisoning. Cite this article as: Coskun A, Demirci B, Akın B, Ferhatlar E, Gündoğan S. The effect of carboxyhemoglobin concentration on thyroid hormones in carbon monoxide poisoning. Endocrinol Res Pract. 2025;29(3):216-222.