The historical practice of bloodletting (venesection or phlebotomy) was a common medical treatment from antiquity through the 19th century. Practitioners used lancets or leeches to remove significant quantities of blood, believing it would balance the body’s “humors” and cure various ailments. This ancient method, which often caused more harm than benefit, is entirely obsolete in contemporary medicine. However, the foundational concept of removing blood for health benefits has been refined into a highly specialized, controlled medical procedure still used today for a small number of specific conditions.
Therapeutic Phlebotomy: The Modern Equivalent
Modern medicine uses a precise intervention called therapeutic phlebotomy. This procedure is performed only under the strict supervision of trained healthcare professionals, such as physicians, nurses, or phlebotomists, within a sterile clinical setting. The treatment is highly targeted and based on current laboratory results. The amount of blood removed is carefully measured, typically 450 to 500 milliliters per session, comparable to a standard blood donation unit.
The blood removal is done for the patient’s direct therapeutic benefit, not for donation. The frequency of the treatment is strictly regulated, sometimes occurring weekly or monthly, until specific blood markers reach a safe range. This measured, controlled approach ensures the patient does not experience the severe fluid loss or complications. The procedure’s goal is to correct a specific imbalance in the blood rather than simply purging a perceived excess.
Medical Conditions Requiring Treatment
Therapeutic phlebotomy is a standard treatment for several rare conditions where the body either produces too many blood cells or accumulates excessive amounts of a harmful substance.
Hereditary Hemochromatosis
This genetic disorder causes the intestines to absorb too much iron from food. This leads to a dangerous buildup of iron in organs like the liver, heart, and pancreas, causing tissue damage and potential organ failure. Removing iron-rich blood is the most effective and cost-efficient method to reduce this total body iron load.
Polycythemia Vera (PV)
PV is a rare blood cancer where the bone marrow produces an excessive number of red blood cells. This overproduction causes the blood to become abnormally thick, increasing its viscosity and significantly raising the risk of blood clots, strokes, and heart attacks. Phlebotomy sessions quickly reduce the number of circulating red blood cells and decrease the blood’s thickness.
Porphyria Cutanea Tarda (PCT)
PCT is a disorder that causes painful, blistering skin lesions upon sun exposure. In PCT, blood removal helps by depleting iron stores in the liver. This subsequently reduces the buildup of porphyrins, the light-sensitive chemicals responsible for the skin damage.
Physiological Goals of Blood Removal
The physiological benefit of therapeutic phlebotomy depends directly on the underlying medical condition.
Treating Polycythemia Vera
For patients with Polycythemia Vera, the main objective is to reduce blood thickness (viscosity) by lowering the hematocrit level. Hematocrit measures the proportion of red blood cells in the total blood volume. Maintaining this level below 45% reduces the risk of cardiovascular death and major thrombotic events. This reduction in red blood cell volume improves blood flow and lowers the risk of dangerous clotting.
Treating Hemochromatosis
The goal for Hemochromatosis is to systematically deplete the body’s stored iron. When blood is removed, the bone marrow is stimulated to produce new red blood cells. To create hemoglobin for these new cells, the body must pull iron from its storage sites, primarily ferritin, drawing down the dangerous excess iron reserves. Each unit of blood removed represents a loss of approximately 200 to 250 milligrams of iron. This process continues until the patient achieves a mild iron-deficient state, protecting the organs from further damage.