Sleep Study in Polycythemia Workup
A sleep study is not routinely indicated for polycythemia workup, but should be considered when specific clinical features suggest sleep-disordered breathing as a potential cause. 1
Approach to Polycythemia Workup
When to Consider Sleep Studies
Sleep studies should be considered in patients with polycythemia who present with specific signs and symptoms suggestive of sleep-disordered breathing 2:
- Snoring
- Witnessed apneas or respiratory pauses
- Nonrestorative sleep and/or excessive daytime sleepiness
- Obesity
- Early morning headaches
- Unexplained desaturation or hypoxemia during sleep, while awake, or with exertion
- History of poorly controlled hypertension or congestive heart failure
Sleep studies may also be warranted in cases of unexplained polycythemia, especially when other common causes have been ruled out 3
Evidence for Sleep Studies in Polycythemia
- Studies have shown that obstructive sleep apnea (OSA) can be associated with polycythemia, though the relationship is not as strong as previously thought 4
- In a study of 335 patients with OSA, only one patient (0.3%) had clinically significant polycythemia, suggesting that OSA is rarely the sole cause of secondary polycythemia 4
- However, in specific populations such as COPD patients, the prevalence of polycythemia is significantly higher in those with coexisting OSA (6.4% vs 2.9%) 5
- In hypogonadal men on testosterone replacement therapy, OSA is associated with an increased risk of developing polycythemia (OR 2.09) 6
Special Considerations
Overlap Syndromes
- Patients with COPD and coexisting OSA (overlap syndrome) have a higher prevalence of polycythemia than those with COPD alone 5
- The percentage of total sleep time with oxygen saturation below 90% (TS90) is independently associated with increased odds of polycythemia in these patients 5
Secondary vs. Primary Polycythemia
- It's important to note that the presence of OSA does not exclude primary polycythemia vera 7
- In patients with risk factors for secondary polycythemia (like OSA), screening for JAK2 mutations and measuring erythropoietin levels should still be considered to avoid missing a diagnosis of polycythemia vera 7
Practical Recommendations
- For patients with unexplained polycythemia, a comprehensive sleep history should be obtained, focusing on symptoms of sleep-disordered breathing 2
- Validated screening tools like the Epworth Sleepiness Scale or Pittsburgh Sleep Quality Index can help identify patients who would benefit from formal sleep testing 2, 1
- In patients with polycythemia and clinical features suggesting sleep-disordered breathing, a formal polysomnography is appropriate for diagnostic confirmation 2, 3
- For patients with polycythemia without symptoms of sleep-disordered breathing, routine sleep studies are not recommended 2, 4
By following these guidelines, clinicians can appropriately select patients with polycythemia who would benefit from sleep studies while avoiding unnecessary testing in those unlikely to have sleep-disordered breathing as the underlying cause.