What is Venesection (Phlebotomy)?
Venesection, also known as phlebotomy, is a therapeutic medical procedure involving the removal of blood from a vein to reduce iron overload or red blood cell mass in specific conditions. 1
Primary Medical Indications
Venesection is indicated in modern medical practice for only a few specific conditions:
- Hereditary hemochromatosis (HFE-HC): The primary and most common indication for therapeutic venesection, where it serves as the accepted standard of care for iron depletion 1
- Polycythemia vera (PV): To reduce elevated hematocrit levels and prevent thrombotic complications 1
- Porphyria cutanea tarda: For management of this metabolic disorder 2
Mechanism and Therapeutic Goals
For Hemochromatosis
The procedure works by removing excess iron from the body through blood removal, as each unit of blood contains approximately 200-250 mg of iron. 1
Treatment targets include:
- Initial phase: Weekly therapeutic phlebotomy targeting serum ferritin <50 μg/L 1, 3
- Maintenance phase: Phlebotomy every 3-6 months maintaining ferritin at 50-100 μg/L 1, 3
- Volume removed: Typically 350-500 ml of blood per session 4
For Polycythemia Vera
Aggressive phlebotomy maintaining hematocrit <45% (or <42% in women and African Americans) is essential to prevent thrombotic complications. 1
- Historical data demonstrates median survival <2 years in non-phlebotomized PV patients versus >10 years with aggressive treatment 1
- Vascular occlusive episodes increase progressively at hematocrit levels >44% 1
Clinical Benefits and Outcomes
Mortality Impact
Adequately phlebotomized hemochromatosis patients show 5-year survival of 93% compared to 48% in inadequately treated patients (10-year survival 78% vs 32%). 1
- Survival of treated patients without cirrhosis and diabetes equals that of the normal population 1
- Long-term unwanted effects of venesection have not been reported 1
Symptom Improvement
Clinical improvements documented with phlebotomy include: 1
- Fatigue reduction
- Normalization of elevated transaminases
- Improvement in skin pigmentation
- Fibrosis score improvement in 35-69% of cases (depending on initial score)
- Resolution of esophageal varices in cirrhotic patients
Important caveat: Arthralgia typically does not improve with iron depletion, and improvement in endocrinological/cardiological abnormalities varies based on pre-existing tissue damage 1
Monitoring Requirements
At each venesection session, hemoglobin and hematocrit must be monitored. 1, 3
- Phlebotomy should be postponed if anemia develops (hemoglobin <12 g/dL) 3
- Discontinue if hemoglobin <11 g/dL 3
- Serum ferritin monitoring frequency depends on absolute concentration: every 3 months when high, more frequently as it approaches normal range 1
Safety Considerations
Phlebotomy must be performed under careful conditions with appropriate monitored fluid replacement to avoid hypotension and fluid overload, especially in patients with cardiovascular disease. 1
The procedure is generally safe with few side effects when performed by persons familiar with the technique and management of potential complications 2
Historical Context
While venesection was widely applied historically for various ailments, modern evidence-based medicine restricts its use to the specific conditions listed above where clear mortality and morbidity benefits have been demonstrated 2