Q: My girlfriend's father has been diagnosed with a specific type of anemia. He is now receiving frequent blood transfusions. He is in his early 70s. How many pints of blood are in a person's body? How many can they continue to receive? His last blood count was 20. At what stage does this become an impossible situation?

 A: There are several anemias that occur with some frequency in the elderly that can best be managed by frequent blood transfusions. The most common might be the myelodysplastic syndrome, which is a disorder characterized by a lack of cellular components in the bone marrow maturing properly to enter the circulation as red blood cells, white blood cells and platelets.

A unit of whole blood consists of approximately 450 mL of blood, and a unit of packed red blood cells is concentrated into about 200 mL. Most humans, depending on size, have between 12 and 15 units of blood in the body (approximately 6 liters or 1.5 gallons).

With careful administration, blood may be transfused periodically without any long-term danger. In younger individuals who require transfusions throughout their lives, a process called chelation is usually done as well. In chelation, medicines are given to remove the excess iron that accumulates as more blood is transfused. Iron overload syndromes can cause damage to the liver, heart and brain. This can also eventually affect older people who are intensively transfused, and the situation should be monitored by their physicians. Other shorter-term consequences of multiple transfusions include transfusion reactions caused by incompatible blood types, infection, hepatitis and congestive heart failure.

Paul G. Auwaerter, M.D., is an assistant professor in The Johns Hopkins University School of Medicine, with appointments in the divisions of internal medicine and infectious diseases. His research interests include virology and immunology, as well as the study of community-acquired pneumonia.

Last Updated: 3/25/2004
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