In a 53‑year‑old man with obstructive sleep apnea, heart failure, and elevated hematocrit, should the sodium‑glucose cotransporter‑2 (SGLT2) inhibitor and torsemide be discontinued because they are suspected to cause secondary erythrocytosis?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: September 17, 2026 • View editorial policy

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question

Do Not Discontinue the SGLT2 Inhibitor or Torsemide for Suspected Secondary Erythrocytosis

The hematologist's recommendation to discontinue the SGLT2 inhibitor and torsemide due to suspected secondary erythrocytosis is not supported by current evidence and should be strongly reconsidered. In a patient with heart failure and OSA, both medications provide critical mortality and morbidity benefits that far outweigh concerns about elevated hematocrit, particularly when SGLT2 inhibitor-associated erythrocytosis is transient, common, and not associated with increased thrombotic risk.

Why SGLT2 Inhibitors Should Be Continued

Mortality Benefit Trumps Hematocrit Concerns

SGLT2 inhibitors are Class 1A recommendations for heart failure with reduced ejection fraction, demonstrating consistent reductions in cardiovascular death and heart failure hospitalization regardless of diabetes status 1, 2, 1. The Canadian and American heart failure guidelines emphasize these agents as foundational therapy that should be initiated early and maintained 1, 2.

The Erythrocytosis Is Expected and Not Harmful

Recent high-quality evidence directly addresses this concern:

  • Erythrocytosis occurs in only 3.3% of HFrEF patients on SGLT2 inhibitors (incidence rate ratio 4.10 compared to untreated patients), but critically, this was NOT associated with increased one-year thromboembolic risk (HR 0.81,95% CI 0.38-1.74) 3

  • A 2026 prospective registry of 1,244 heart failure patients found that erythrocytosis on SGLT2 inhibitors is transient (rising modestly to 8.0% at 6 months, then returning toward baseline at 5.9% by 12 months) and showed no detectable association with mortality, MACE, or thrombosis 4

  • The hemoglobin increase represents increased erythropoiesis from improved tissue oxygenation, not hemoconcentration from diuresis 5. This is actually a beneficial mechanism contributing to improved myocardial and renal tissue oxygenation

Anemia Is the Real Prognostic Concern

The same registry data show that anemia (not erythrocytosis) carries the dominant adverse prognostic signal in heart failure patients on SGLT2 inhibitors, with adjusted HRs for all-cause death of 2.23-2.55 across timepoints 4. If anything, monitoring should focus on preventing or treating anemia, not worrying about modest hematocrit elevations.

Why Torsemide Should Be Continued

Loop diuretics like torsemide are essential for managing volume status in heart failure 6. While diuretics can theoretically cause hemoconcentration, the FDA label does not list erythrocytosis as a recognized adverse effect 6. The concern about diuretic-induced hemoconcentration causing secondary erythrocytosis is not evidence-based.

Careful attention to volume status is warranted when SGLT2 inhibitors and loop diuretics are used together due to their combined diuretic effects 1, but this is managed through clinical monitoring and dose adjustment, not discontinuation.

Address the Obstructive Sleep Apnea

OSA itself is a well-established cause of secondary erythrocytosis through chronic intermittent hypoxia stimulating erythropoietin production. The guidelines recommend:

  • Formal sleep assessment to confirm OSA diagnosis (Class 2a, Level C-LD) 2, 7
  • Continuous positive airway pressure (CPAP) therapy is reasonable to improve sleep quality and decrease daytime sleepiness (Class 2a, Level B-R) 2, 7

Treating the OSA with CPAP is far more likely to address the erythrocytosis than stopping guideline-directed heart failure medications.

Clinical Algorithm

  1. Continue both SGLT2 inhibitor and torsemide - these are life-saving medications in heart failure
  2. Initiate or optimize CPAP therapy for the OSA - this addresses a proven cause of secondary erythrocytosis
  3. Monitor hemoglobin/hematocrit at 6 and 12 months:
    • Expect transient modest increases (typically 0.5-1.0 g/dL hemoglobin increase) 8
    • Watch for anemia (more prognostically important) 4
    • Erythrocytosis typically peaks at 6 months and trends back toward baseline 4
  4. Assess volume status clinically - adjust diuretic dose if needed, but don't discontinue
  5. Check for other causes of erythrocytosis if hematocrit remains severely elevated:
    • Smoking status (independent risk factor) 9
    • Chronic lung disease severity
    • Testosterone use
    • Primary polycythemia vera (JAK2 mutation)

Common Pitfalls to Avoid

  • Do not stop SGLT2 inhibitors for modest hematocrit elevations - the mortality benefit far exceeds any theoretical thrombotic risk, which has not been demonstrated in clinical trials 3, 4

  • Do not attribute all erythrocytosis to medications - OSA is likely the primary driver here and requires treatment regardless

  • Do not confuse hemoconcentration with true erythrocytosis - SGLT2 inhibitors increase red blood cell mass through improved erythropoiesis, not just volume contraction 5

  • Recognize that baseline hemoglobin is the strongest predictor of subsequent erythrocytosis 4 - patients starting with higher normal values are more likely to cross into erythrocytosis range, but this doesn't change the risk-benefit calculus

The only scenario where temporary SGLT2 inhibitor discontinuation is recommended is 3-4 days before elective surgery to reduce perioperative metabolic acidosis risk (Class 1, Level C-LD) 10, which is not relevant to this clinical situation.

References

Related Questions

How should we manage a heart‑failure patient on an SGLT2 inhibitor and torsemide with a modest hematocrit rise due to obstructive sleep apnea, given that it is not clonal polycythemia vera and phlebotomy may cause iron‑deficiency anemia?
Can a reduced ejection fraction cause a significant decrease in hemoglobin?
In a 53‑year‑old man with combined systolic‑diastolic heart failure, persistent erythrocytosis (hemoglobin 18.3 g/dL, hematocrit 54 %, RBC 5.97 ×10^12/L), history of pulmonary sarcoidosis in remission, normal cardiac imaging and electrophysiology, and a benign 0.62‑mm gallbladder polyp, how should I proceed with management given that the hematologist declined to treat the erythrocytosis?
What is the recommended treatment for subclavian artery stenosis?
In an 83‑year‑old man with a blood pressure of 148/88 mm Hg who had his telmisartan dose increased from 40 mg to 80 mg two weeks ago while continuing pravastatin 40 mg, what is the appropriate next step in managing his hypertension?
What is the appropriate workup for multiple sclerosis-associated myopathy and autoimmune peripheral nerve demyelination?
In a 37-year-old female with fever of 38.4 °C, frontoparietal headache, leukocytosis with neutrophil predominance, and no nuchal rigidity, focal neurological deficits, or papilledema, which diagnostic test should be performed first?
Can prednisone cause generalized tingling (paresthesia) in patients?
Which laboratory tests are most appropriate for evaluating a patient prior to major dental work?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.