Phlebotomy, the act of drawing blood from a vein, is most commonly associated with diagnostic testing, but it also serves a distinct therapeutic purpose. Therapeutic phlebotomy involves removing a specific volume of blood from the body to manage certain chronic conditions. This intervention is prescribed when a patient has an excessive amount of a particular component in their bloodstream, such as iron or red blood cells, which can lead to organ damage or circulatory problems. The blood removed during this medical procedure is typically discarded, unlike blood donated for general use.
The Purpose and Mechanism of Therapeutic Blood Removal
The physiological goal of therapeutic phlebotomy is primarily to reduce the concentration of a harmful component or decrease the overall thickness of the blood. For conditions involving iron overload, removing whole blood forces the body to create new red blood cells. To synthesize the required hemoglobin, the body uses stored iron (often ferritin) from tissues and organs. This process effectively mobilizes and depletes the excessive iron accumulation causing toxicity.
Reducing the total volume of blood also lowers its viscosity, or thickness, which can be abnormally high in certain blood disorders. Thickened blood slows flow, increasing the risk of dangerous blood clots and reducing oxygen delivery to tissues. Removing blood normalizes viscosity, improving circulation and lowering the chance of thrombotic events. Sometimes, the removed blood volume is immediately replaced with a saline solution to maintain circulating fluid levels and prevent a sudden drop in blood pressure.
Key Conditions Treated
Therapeutic blood removal is the primary treatment for several disorders characterized by an overabundance of a blood component.
Hereditary Hemochromatosis
This is one of the most common genetic conditions treated, where a faulty gene causes the body to absorb too much iron from the diet. This excess iron gradually builds up in organs like the liver, heart, and pancreas, potentially leading to cirrhosis, heart failure, or diabetes if left untreated. Regular phlebotomy sessions are performed to systematically draw down the patient’s total body iron stores until they reach a safe level.
Polycythemia Vera (PV)
PV, a slow-growing type of blood cancer, is another major indication for this procedure. PV causes the bone marrow to produce an abnormally high number of red blood cells, which significantly increases the blood’s viscosity. This thickened blood dramatically elevates the patient’s risk of experiencing life-threatening events like stroke, heart attack, or pulmonary embolism. The treatment aims to reduce the hematocrit (the percentage of red blood cells in the blood) to a target level, typically below 45 percent, to prevent these complications.
Porphyria Cutanea Tarda (PCT)
PCT also benefits from therapeutic phlebotomy. It is a disorder related to a buildup of porphyrins, compounds involved in the production of heme. In PCT, iron overload exacerbates the accumulation of these porphyrin molecules in the liver and skin, leading to painful, blistering skin lesions, especially after sun exposure. Reducing the iron stores through phlebotomy is highly effective in treating the skin symptoms and managing the underlying liver accumulation. The procedure is a sustained management strategy to prevent disease progression and organ damage.
Preparation and the Phlebotomy Process
A therapeutic phlebotomy session requires specific preparation to ensure patient safety and maximize the procedure’s effectiveness. Patients are advised to be well-hydrated by drinking extra fluids before the appointment, which helps maintain blood volume and makes vein access easier. It is also recommended that the patient consume a light meal beforehand to prevent lightheadedness or dizziness during or after the blood draw.
The procedure itself is similar to a standard blood donation and is typically performed by a trained healthcare professional in a clinic, hospital, or blood center. A needle is inserted into a peripheral vein, most often in the arm, and the prescribed volume of whole blood is collected into a specialized bag. The amount removed is usually one unit, or approximately 450 to 500 milliliters, though this volume can be adjusted based on the patient’s size and overall health status.
The process, from patient preparation to the completion of the blood draw, usually takes between 30 and 60 minutes. During the session, the patient’s vital signs are monitored, and the procedure is paused if any adverse reactions, such as severe dizziness or paleness, occur. After the needle is removed, firm pressure is applied to the site for several minutes to prevent bruising or hematoma formation. Patients are typically advised to rest for a short period and continue drinking fluids before resuming their normal daily activities.