What is one bloodwork finding that is a negative prognostic indicator in a patient with OSA?
The correct answer and explanation is:
Correct Answer:
Elevated hematocrit
Explanation (≈300 words):
Obstructive Sleep Apnea (OSA) is a disorder characterized by repetitive episodes of upper airway obstruction during sleep, leading to intermittent hypoxia and sleep fragmentation. One bloodwork finding that serves as a negative prognostic indicator in patients with OSA is elevated hematocrit, also known as polycythemia.
Hematocrit refers to the percentage of red blood cells (RBCs) in the blood. In OSA, recurrent episodes of hypoxia stimulate increased production of erythropoietin (EPO) by the kidneys, which in turn promotes erythropoiesis (RBC production) in the bone marrow. Over time, this leads to an elevated hematocrit level as a compensatory response to chronic low oxygen levels.
An elevated hematocrit is concerning in OSA patients because it increases blood viscosity, which can contribute to hypertension, vascular resistance, and thrombotic events (e.g., stroke or myocardial infarction). High hematocrit levels have been associated with increased cardiovascular morbidity and mortality, particularly when left untreated or when OSA is poorly managed.
Furthermore, polycythemia in OSA is often an indicator of severe or long-standing disease, implying a greater burden of nocturnal hypoxia. It suggests that the patient’s OSA may be contributing significantly to systemic effects beyond just disrupted sleep—such as right heart strain, pulmonary hypertension, or even cor pulmonale in advanced cases.
Monitoring hematocrit in OSA patients can also help evaluate treatment effectiveness, such as with continuous positive airway pressure (CPAP) therapy. Effective treatment often leads to reduced hypoxic episodes and a subsequent normalization of hematocrit over time.
In summary, elevated hematocrit is a negative prognostic indicator in OSA because it reflects chronic hypoxia, predicts increased cardiovascular risk, and may indicate more severe disease requiring aggressive management.