What is the treatment for a patient with high hematocrit (Hct)?

Treatment for High Hematocrit (Hct)

The primary treatment for high hematocrit is phlebotomy to maintain a hematocrit level below 45%, along with low-dose aspirin (81-100 mg/day) if there are no contraindications. 1

Initial Assessment and Risk Stratification

• Determine if high hematocrit is due to polycythemia vera (PV) or secondary causes (secondary polycythemia) 1, 2
• For PV, risk stratification should be performed:
  • Low-risk: Age <60 years and no history of thrombosis 1
  • High-risk: Age ≥60 years or history of thrombosis 1

Treatment Algorithm

For Polycythemia Vera:

All Patients (Regardless of Risk):

• Phlebotomy to maintain hematocrit <45% 1
  • Induction phase: 300-450 ml blood withdrawn weekly or twice weekly until target hematocrit is reached 1
  • Maintenance phase: Same blood volume per phlebotomy with intervals determined by hematocrit levels 1
• Low-dose aspirin (81-100 mg/day) unless contraindicated 1
• Aggressive management of cardiovascular risk factors 1

High-Risk Patients (Additional Treatment):

• Cytoreductive therapy in addition to phlebotomy and aspirin 1
• First-line cytoreductive options:
  • Hydroxyurea (most commonly used) 1
  • Interferon alfa-2b, peginterferon alfa-2a, or peginterferon alfa-2b (preferred for younger patients and pregnant patients) 1

Additional Indications for Cytoreductive Therapy:

• Poor tolerance to phlebotomy 1
• Symptomatic or progressive splenomegaly 1
• Severe disease-related symptoms (pruritus, night sweats, fatigue) 1
• Platelet count >1500 × 10^9/L 1
• Leukocyte count >15 × 10^9/L 1

For Secondary Polycythemia:

• Treat underlying cause (COPD, sleep apnea, smoking, etc.) 1
• Judicious phlebotomy to hematocrit of 55-60% for patients with cyanotic congenital heart disease or high oxygen-affinity hemoglobinopathy 1
• For post-renal transplant erythrocytosis, consider ACE inhibitors or angiotensin II receptor blockers 1

Special Considerations

• Target hematocrit may need individualization (e.g., 42% for women and/or patients with progressive or residual vascular symptoms) 1
• In patients with hypoxic conditions, overly aggressive phlebotomy should be avoided due to risk of stroke 1
• For patients with pulmonary arterial hypertension and right-to-left shunts, phlebotomy is indicated if hematocrit is above 65% and patient is symptomatic (headache, poor concentration) 1
• Patients requiring ≥3 phlebotomies per year while on hydroxyurea have a higher risk of thrombosis and may need adjustment of cytoreductive therapy 3
• Iron supplementation should be avoided unless there is documented severe tissue iron deficiency with detrimental symptoms (pica, mouth paresthesia, esophagitis, restless legs) 1

Monitoring and Follow-up

• Regular monitoring of hematocrit levels 1
• Monitor for thrombotic events, which are the main cause of morbidity and mortality 1
• Watch for disease progression to myelofibrosis or acute myeloid leukemia 1, 2
• For patients on cytoreductive therapy, monitor for resistance or intolerance 1

Treatment Response Criteria

• Complete response: hematocrit <45% without phlebotomy, platelet count ≤400 × 10^9/L, WBC count ≤10 × 10^9/L, and no disease-related symptoms 1
• Partial response: hematocrit <45% without phlebotomy or response in three or more other criteria 1

Cautions and Pitfalls

• Avoid iron supplementation in PV patients unless specifically indicated, as it may worsen erythrocytosis 1
• Be cautious with aspirin in patients with extreme thrombocytosis (≥1000 × 10^9/L) due to risk of acquired von Willebrand disease and bleeding 2
• Recognize that phlebotomy alone may not be sufficient for high-risk PV patients 1
• The CYTO-PV study demonstrated that maintaining hematocrit <45% resulted in significantly lower rates of cardiovascular death and thrombotic events compared to a target of 45-50% 1