What is the treatment for a patient with dapagliflozin (Forxiga) induced polycythemia?

Dapagliflozin-Induced Polycythemia: Management Strategy

In most cases, dapagliflozin-induced polycythemia does not require specific treatment beyond monitoring, as the hematocrit elevation is typically mild, physiologic, and associated with the cardiovascular and renal benefits of the medication.

Understanding the Mechanism

Dapagliflozin increases hematocrit through two distinct mechanisms that are actually beneficial rather than pathologic:

• Hemoconcentration from osmotic diuresis: The drug causes mild volume contraction, which concentrates red blood cells 1
• Enhanced erythropoiesis: Dapagliflozin suppresses hepcidin (a negative regulator of iron metabolism), increases erythroferrone, and transiently elevates erythropoietin, leading to genuine increases in red cell mass 2

The hematocrit increase is typically modest (2-5% absolute increase) and stabilizes after the first few months of therapy 1, 3.

Clinical Decision Algorithm

Step 1: Confirm True Polycythemia vs. Expected Physiologic Response

Check baseline and current hematocrit values:

• If hematocrit increased by <5% from baseline and remains <52% in men or <48% in women, this represents the expected pharmacologic effect and requires no intervention beyond continued monitoring 2
• If hematocrit is ≥52% in men or ≥48% in women, proceed to Step 2 4

Step 2: Rule Out Underlying Myeloproliferative Disorder

Critical distinction: Dapagliflozin can unmask pre-existing polycythemia vera rather than cause it de novo 5

Obtain the following if hematocrit is significantly elevated:

• Complete blood count with differential (look for elevated WBC >12,000/mm³ and platelets >400,000/mm³, which suggest polycythemia vera rather than drug effect) 5
• JAK2V617F mutation testing 5
• Serum erythropoietin level (should be normal or slightly elevated with dapagliflozin; suppressed levels suggest polycythemia vera) 2, 5

If polycythemia vera is confirmed: Discontinue dapagliflozin and refer to hematology for management with phlebotomy and hydroxyurea if high-risk (age ≥60 or prior thrombosis) 4, 5

Step 3: Assess Cardiovascular and Renal Indication Strength

For patients with heart failure or chronic kidney disease (the primary indications for dapagliflozin):

• Do NOT discontinue dapagliflozin for mild-to-moderate hematocrit elevation, as the mortality benefit far outweighs theoretical thrombotic risk 1, 6
• Dapagliflozin reduces cardiovascular death or heart failure hospitalization by 26% and kidney disease progression by 39-44% 1, 6, 3
• The hematocrit increase is part of the therapeutic mechanism and correlates with improved outcomes 2, 3

For patients using dapagliflozin primarily for glycemic control (without heart failure or CKD):

• Consider alternative glucose-lowering agents (GLP-1 receptor agonists, DPP-4 inhibitors) if hematocrit exceeds 52% in men or 48% in women and there are additional thrombotic risk factors 7

Step 4: Manage Thrombotic Risk Factors

Rather than stopping dapagliflozin, optimize modifiable risk factors:

• Ensure adequate hydration: Counsel patients to maintain fluid intake of at least 2 liters daily to counteract the osmotic diuresis 7, 8
• Assess volume status: If signs of volume depletion exist, reduce concurrent diuretic doses rather than stopping dapagliflozin 1, 7, 8
• Low-dose aspirin: Consider 81 mg daily if hematocrit is elevated AND patient has cardiovascular risk factors or prior thrombosis, provided platelet count is <1,500 × 10⁹/L 4
• Address smoking, obesity, and hypertension: These are more significant thrombotic risk factors than the mild hematocrit elevation from dapagliflozin 4

Step 5: Monitoring Strategy

For patients continuing dapagliflozin with elevated hematocrit:

• Recheck CBC within 2-4 weeks after any intervention 7, 8
• Monitor CBC every 3 months for the first year, then every 6 months if stable 7
• Educate patients about symptoms of thrombosis (chest pain, unilateral leg swelling, sudden neurologic changes) and instruct them to seek immediate care 4

When to Actually Discontinue Dapagliflozin

Absolute indications for stopping the medication:

• Confirmed diagnosis of polycythemia vera (JAK2V617F positive with elevated WBC/platelets and suppressed erythropoietin) 5
• Hematocrit >55% in men or >52% in women despite hydration optimization 4
• Development of thrombotic event temporally related to hematocrit elevation 4
• Patient preference after informed discussion of risks vs. cardiovascular/renal benefits 1

Common Pitfalls to Avoid

• Do not reflexively stop dapagliflozin in patients with heart failure or CKD based solely on hematocrit elevation, as this exposes them to preventable cardiovascular death and kidney failure 1
• Do not confuse drug-unmasked polycythemia vera with drug-induced polycythemia: The former requires hematology referral; the latter is a benign, expected effect 5
• Do not order bone marrow biopsy unless JAK2V617F is positive or there are other cytopenias suggesting myeloproliferative disorder 5
• Do not assume the hematocrit rise is purely hemoconcentration: Dapagliflozin genuinely increases red cell mass through hepcidin suppression, which is part of its cardioprotective mechanism 2

Special Consideration: Temporary Discontinuation During Acute Illness

If a patient on dapagliflozin develops acute illness with reduced oral intake, fever, vomiting, or diarrhea:

• Temporarily hold dapagliflozin to prevent volume depletion and diabetic ketoacidosis 7, 8
• Resume once oral intake is re-established and patient has recovered 7, 8
• This "sick day rule" applies regardless of hematocrit level 7