What is the management for a patient with erythrocytosis, as indicated by a hematocrit of 50.9, hemoglobin of 16.6, and red blood cell count of 5.91?

Management of Erythrocytosis

Immediate Assessment Required

Your patient's values (hematocrit 50.9%, hemoglobin 16.6 g/dL, RBC 5.91) indicate mild erythrocytosis that does NOT meet criteria for therapeutic phlebotomy, which is reserved only for hemoglobin >20 g/dL and hematocrit >65% with hyperviscosity symptoms. 1, 2, 3

Diagnostic Workup

Before any intervention, you must determine the underlying cause:

• Assess for dehydration first - this can cause relative (pseudo) erythrocytosis and must be corrected before considering any treatment 2, 3
• Evaluate for symptoms of hyperviscosity including headache, fatigue, poor concentration, pruritus, erythromelalgia, or transient visual changes 3, 4
• Order JAK2 mutation testing - more than 95% of polycythemia vera (PV) cases have a JAK2 gene variant, which distinguishes primary from secondary causes 4
• Screen for secondary causes including tobacco smoking, sleep apnea, cardiovascular disorders, and malignancy (particularly renal cell carcinoma and testicular seminoma) 4, 5, 6
• Check iron status with serum ferritin and transferrin saturation 3
• Obtain chest x-ray and complete blood count to evaluate for underlying pathology 7

Management Algorithm Based on Diagnosis

If Polycythemia Vera is Confirmed (JAK2 positive):

All PV patients require therapeutic phlebotomy targeting hematocrit <45% regardless of sex, plus low-dose aspirin 81-100 mg daily. 8, 1, 4 The CYTO-PV trial demonstrated that maintaining hematocrit <45% significantly reduced cardiovascular death and major thrombotic events (HR 3.91 for hematocrit 45-50% group). 8

Phlebotomy protocol for PV:

• Remove 400-500 mL per session, replaced with 750-1000 mL isotonic saline 1, 2
• Perform weekly or fortnightly until hematocrit <45% is achieved 1
• In elderly patients or those with cardiovascular disease, consider smaller volumes (250-300 mL) to minimize hemodynamic stress 1

Risk stratification determines additional therapy:

• High-risk patients (age >60 years OR prior thrombosis history) require cytoreductive therapy with hydroxyurea in addition to phlebotomy and aspirin 8, 4
• Low-risk patients receive aspirin plus phlebotomy alone 8

If Secondary Erythrocytosis:

Address the underlying cause - treatment of the primary condition (smoking cessation, CPAP for sleep apnea, tumor resection) typically resolves the erythrocytosis 5, 6

Phlebotomy is only indicated if:

• Hemoglobin exceeds 20 g/dL AND hematocrit exceeds 65% 1, 2, 3
• Hyperviscosity symptoms are present 2, 3
• Dehydration and anemia have been excluded 1, 2

Critical Monitoring Requirements

Monitor iron status with every phlebotomy session using peripheral blood smear and serum ferritin - iron deficiency is dangerous even in erythrocytosis because it reduces oxygen-carrying capacity, decreases red cell deformability, and paradoxically increases stroke risk. 1, 2, 3 This is a common and dangerous pitfall. 1

Never perform routine repeated phlebotomies without monitoring iron status. 1, 3 Research indicates that phlebotomy may paradoxically increase thrombotic risk in some erythrocytosis conditions, particularly when it induces iron deficiency. 9

Common Pitfalls to Avoid

• Do not phlebotomize based solely on elevated hematocrit - your patient's values do not meet the threshold (Hct >65%, Hgb >20 g/dL) for intervention 1, 2, 3
• Do not perform phlebotomy in the presence of dehydration - correct hydration status first 1, 2
• Avoid creating iron deficiency through excessive phlebotomy - this worsens oxygen delivery and increases stroke risk despite lowering hematocrit 8, 2, 3
• Do not assume all erythrocytosis requires phlebotomy - most secondary causes do not carry increased thrombotic risk and resolve with treatment of the underlying condition 9

Alternative Therapies

Erythrocytapheresis is superior to traditional phlebotomy when available, extending intervals between treatments from 20 days-2 months to 2-7 months, particularly useful during induction phase. 1, 2

Iron chelation with deferasirox can be considered only when phlebotomy is not possible, after careful risk-benefit assessment, though evidence is weak. 1, 2

For Your Specific Patient

Given hematocrit 50.9% and hemoglobin 16.6 g/dL:

• Ensure adequate hydration and recheck values 3
• Complete diagnostic workup including JAK2 mutation testing 4
• If PV is confirmed, initiate phlebotomy protocol to achieve hematocrit <45% plus aspirin 8, 1, 4
• If secondary cause identified, treat underlying condition and monitor 5, 6
• Do not perform phlebotomy until diagnosis is established and criteria are met 1, 2, 3