Predicting Hypothyroidism in OSA Patients Using Lymphocyte Count

A recent study published in BMC Pulmonary Medicine suggests that the prevalence of hypothyroidism increases with higher lymphocyte counts in patients with obstructive sleep apnea (OSA).¹

Xiaoyan Fang and colleagues from the Department of Respiratory and Critical Care Medicine, Tianjin Medical University General Hospital, China, conducted a retrospective study to investigate the relationship between lymphocyte levels and hypothyroidism specifically in OSA patients. Study participants underwent routine blood tests, including thyroid function profiles, alongside nocturnal sleep monitoring. Logistic regression analysis was used to identify independent predictors of hypothyroidism, while receiver operating characteristic (ROC) analysis determined the optimal lymphocyte count cutoff for predicting hypothyroidism.

The study included 920 patients attending the Sleep Center at Tianjin Medical University General Hospital. Overall, 4.46% (n=41) were diagnosed with hypothyroidism, with prevalence higher in females (6.6%) than males (3.4%). The majority, 95.5% (n=879), had normal thyroid function. OSA patients with hypothyroidism had a higher body mass index (BMI) compared to controls (34.78 vs 32.38) and higher Epworth Sleepiness Scale (ESS) scores (10 vs 6).

Analysis revealed that both lymphocyte percentage and absolute lymphocyte count were significantly elevated in hypothyroid patients compared to controls, particularly in the overall OSA population and in males. Subgroup analysis showed that lymphocyte counts were notably higher in patients under 60 years old and in those with mild to moderate OSA who also had hypothyroidism.

The study identified lymphocyte count, ESS score, and sex as independent predictors of hypothyroidism in OSA patients. ROC curve analysis indicated an increased risk of hypothyroidism with rising lymphocyte counts, with an optimal cutoff of 2.5 × 10⁹/L.

This research highlights a clear correlation between lymphocyte count and hypothyroidism prevalence in OSA patients, including both subclinical and overt forms. Higher lymphocyte counts were associated with an increased likelihood of hypothyroidism. Given that hypothyroidism and OSA share clinical features such as excessive daytime sleepiness, lethargy, and obesity, lymphocyte count—a simple and widely available test—could serve as a practical screening tool to identify OSA patients at risk for hypothyroidism. Early identification may facilitate timely management and improve patient outcomes. The authors recommend further studies to validate these findings and to explore the underlying mechanisms of this association.

Reference

1. Xiaoyan Fang, et al. The association of lymphocyte with hypothyroidism in obstructive sleep apnea. BMC Pulm Med. 2024 Jan 27;24(1):60. doi: 10.1186/s12890-024-02872-7