Thyroid function and hematological parameters. A cross-sectional study on a general adult population

Abstract

Background. Thyroid hormones play a crucial role in regulating hematopoiesis. However, the impact of subclinical dysthyroidism on hematological parameters and its clinical implications remain understudied.

Objectives. To investigate variations in hematological parameters among patients with subclinical thyroid dysfunction.

Methods. Cross-sectional stud. N=1516. Variables: structured questionnaire with demographic data, chronicity, current pharmacological treatment, tobacco and alcohol use, physical activity, and blood samples were obtained for the determination of hematological parameters and thyroid function.

Results. Prevalence of thyroid disease: 9.43%; subclinical hypothyroidism and hyperthyroidism: 5.31% and 1.49%, respectively. 66.7% of participants with subclinical hypothyroidism were women. There is an association between smoking habit and thyroid status, 47.6% of participants with subclinical hyperthyroidism being former smokers, while 53.5% and 68% of euthyroid and subclinical hypothyroid participants, respectively, were non-smokers. Among the hematological parameters, only hematocrit is lower in patients with subclinical hypothyroidism (p=0.044). Regression analysis found that red blood cells, hemoglobin, hematocrit, and platelets increase with increasing T4, with these parameters being higher in men than in women, except for platelets, which are more numerous in women.

Conclusions. We found a low prevalence of subclinical thyroid disease, which is more common in women. Hematocrit is the only parameter that decreases in subclinical hypothyroidism. Red blood cell count, hemoglobin, hematocrit, and platelet values increase as T4 levels increase.