Obstructive Sleep Apnea-induced Secondary Polycythemia with Normal Erythropoietin Levels: A Case Report and Pathophysiological Insights

Secondary polycythemia is a well-recognized consequence of chronic hypoxemia, commonly attributed to conditions such as chronic obstructive pulmonary disease, high-altitude exposure, and congenital heart disease.Sleep-disordered breathing associated with chronic respiratory failure, such as obesity hypoventilation syndrome, can also contribute to secondary polycythemia.However, obstructive sleep apnea (OSA) in the absence of daytime hypoxemia, presenting with secondary polycythemia and normal erythropoietin levels, is less frequently reported.We present a case of a 45-year-old male with severe OSA who developed secondary polycythemia, ultimately responding well to continuous positive airway pressure therapy.This case emphasizes the need for sleep disorder evaluation in unexplained polycythemia.