What is the role of oxygen saturation tests in the workup of polycythemia vera (PV)?

Updated: Aug 20, 2019
  • Author: Srikanth Nagalla, MBBS, MS, FACP; Chief Editor: Koyamangalath Krishnan, MD, FRCP, FACP  more...
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Answer

Measuring arterial oxygen saturation (SaO2) and carboxyhemoglobin (COHb) levels is important to rule out hypoxia as a secondary cause for erythrocytosis. Pulse oximetry is the most convenient method for measuring SaO2; however, in people who smoke cigarettes, the COHb must be determined directly and subtracted to give an accurate SaO2 value. A value below 92% indicates a causal relationship with erythrocytosis. If the fall is due to increased COHb, this is less likely to cause erythrocytosis.

Nocturnal oxygen desaturation due to sleep apnea is observed in 20% of patients.


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