Donated blood saves lives across a surprisingly wide range of medical situations, from emergency trauma care to cancer treatment to helping premature babies survive their first weeks. In the United States alone, hospitals need roughly 29,000 units of red blood cells, 5,000 units of platelets, and 6,500 units of plasma every single day. Most donated blood is separated into these individual components so that a single donation can help multiple patients with different needs.
How One Donation Becomes Multiple Treatments
After collection, a unit of whole blood is typically split into three main components: red blood cells, platelets, and plasma. Each serves a distinct medical purpose and has a different shelf life. Red blood cells can be stored for up to 42 days in most countries (up to 49 days in parts of Europe), while platelets last only about five days. Plasma can be frozen and stored for a year or longer.
This separation is what makes modern blood banking so efficient. A trauma patient might need red blood cells to replace blood loss but not platelets. A leukemia patient might need both. A burn victim might primarily need plasma. By splitting donations into parts, blood banks match the right component to the right patient rather than using whole blood for everything.
Trauma and Emergency Surgery
Emergency care is what most people picture when they think about blood donations, and the numbers involved can be staggering. Severely injured trauma patients who need massive transfusions receive a median of 10 whole blood equivalent units in the first 24 hours. About 75% of these patients require 14 units or fewer, but the most critically injured 10% need 17 units or more. A single car accident victim can consume the donations of a dozen or more people in a single day.
These patients typically receive a combination of red blood cells to carry oxygen, plasma to help with clotting, and platelets to seal damaged blood vessels. The speed of transfusion matters enormously in trauma. Hospitals maintain emergency blood supplies precisely because waiting even minutes for the right blood type can mean the difference between survival and death.
Cancer Treatment
Cancer patients are among the largest ongoing consumers of donated blood. Nearly all patients with cancer experience some degree of anemia, either from the disease itself or from the effects of chemotherapy. How much blood they need depends heavily on the type of cancer.
Patients with solid tumors (breast, lung, colon) may need only a few red blood cell units spread across their entire course of chemotherapy, since the cancer doesn’t typically interfere with blood production in the bone marrow. Blood cancers like leukemia are a different story entirely. Leukemia cells crowd the bone marrow and prevent it from making normal blood cells, leaving patients profoundly low on both red blood cells and platelets. During the initial phase of leukemia treatment, patients historically needed 30 to 60 units of red blood cells in the first two months alone. That number has come down over time with better transfusion management, but leukemia patients still universally require both red blood cell and platelet support throughout treatment.
Sickle Cell Disease and Chronic Conditions
Some patients need regular transfusions not for weeks or months, but for their entire lives. Sickle cell disease is one of the most common reasons for long-term transfusion therapy. These patients receive blood to dilute the abnormal sickle-shaped red blood cells and prevent painful crises, strokes, and organ damage. Blood use in adults with sickle cell disease has been rising, with one UK center reporting an increase from 1.7 to 3.86 units per patient per year over a decade. Children with the disease are also being transfused more frequently, with transfusion rates during hospital admissions doubling over a similar period.
Other chronic conditions requiring ongoing transfusions include thalassemia (another inherited blood disorder), bone marrow failure syndromes, and chronic kidney disease when the kidneys stop producing enough of the hormone that stimulates red blood cell production.
Premature and Newborn Babies
Premature infants, particularly those born weighing less than about 3.3 pounds or before 32 weeks of gestation, frequently need transfusions. These babies have tiny blood volumes, underdeveloped bone marrow, and often require frequent blood draws for monitoring, which depletes their already limited supply. The volumes are small compared to adult transfusions, typically around 16 milliliters per kilogram of body weight, but many of these infants need multiple transfusions during their stay in the neonatal intensive care unit.
The most common reason for transfusing red blood cells to premature babies is anemia while they’re on breathing support. Platelets are transfused when counts drop dangerously low, and plasma and a clotting product called cryoprecipitate are primarily reserved for infants who are actively bleeding.
Childbirth Complications
Postpartum hemorrhage, or severe bleeding after delivery, remains one of the leading causes of maternal death worldwide. When a mother loses a dangerous volume of blood during or after childbirth, transfusion can be lifesaving. The World Health Organization recommends blood transfusion as a key intervention to stabilize women with ongoing hemorrhage. Mothers who become severely anemic may also need intravenous iron treatments after hemorrhage or when oral supplements aren’t effective.
Burn Patients
Severe burns destroy large areas of skin and cause massive fluid loss, making plasma the most critical blood product for these patients. Plasma helps restore blood volume and provides clotting proteins that prevent further bleeding. Pediatric burn patients receive a median of 2.5 units of plasma during resuscitation, though adults with extensive burns can require significantly more. One study of adult burn patients found an average of 11.4 units of plasma per patient. The amount scales with the percentage of the body that’s burned.
Medicines Made From Plasma
Not all donated plasma goes directly into patients. A significant portion is sent to pharmaceutical manufacturers who extract specific proteins to create medicines used by millions of people. The three most important products are albumin, clotting factor concentrates, and immunoglobulin therapies.
Albumin, the most abundant protein in blood, is used to treat patients with liver failure, severe burns, and dangerously low blood pressure. Clotting factor concentrates, particularly factor VIII, transformed the treatment of hemophilia A from a life-limiting condition into a manageable one. Before these concentrates became available, people with hemophilia had little effective treatment for their uncontrolled bleeding episodes.
Immunoglobulin therapy has become one of the biggest drivers of plasma demand. These concentrated antibody solutions are used in two very different ways: replacing missing antibodies in people with immune deficiencies, and, at higher doses, treating autoimmune conditions where the immune system attacks the body’s own tissues. Approved uses include Guillain-Barré syndrome (a condition where the immune system damages nerves), Kawasaki disease in children, a bleeding disorder called immune thrombocytopenic purpura, and chronic inflammatory nerve diseases. The growing list of autoimmune conditions treated with immunoglobulin therapy is a major reason why demand for donated plasma continues to rise.
Why Supply Is a Constant Challenge
The combination of short shelf lives, unpredictable demand from trauma and emergencies, and steady consumption by cancer and chronic disease patients means blood banks operate with thin margins. Platelets are the most precarious component, lasting only about five days before they expire. Red blood cells last longer at roughly six weeks, but even that window is tight when a single leukemia patient might need dozens of units over a treatment course. The daily requirement of 29,000 units of red blood cells in the U.S. represents a supply chain that must be continuously replenished, with no synthetic substitute yet available for most blood components.