Plasma is the straw-colored, liquid component of blood, making up about 55% of its total volume. This fluid is mostly water, but it carries hundreds of essential proteins, including antibodies, clotting factors, and albumin. Plasma transports nutrients, hormones, and proteins throughout the body, helping to maintain blood pressure and regulate body temperature. Donated plasma is an irreplaceable resource for treating conditions ranging from acute trauma to chronic diseases. The number of donations required depends entirely on the treatment type, which involves two distinct pathways for the collected plasma.
The Two Primary Uses of Donated Plasma
The destination of the donated plasma dictates the quantity needed for patient treatment. Plasma collected in hospital blood centers is often used for direct transfusion, known as Fresh Frozen Plasma (FFP). FFP is used in acute settings, such as massive trauma or major surgery, to quickly replace lost blood volume and restore clotting ability. This application is typically a single-event intervention meant to stabilize a patient during a medical crisis.
A separate and greater volume of plasma is collected by specialized centers for manufacturing into purified medications. This process, called fractionation, pools plasma from thousands of individual donations to extract specific therapeutic proteins. These Plasma-Derived Medicinal Products (PDMPs) include concentrated clotting factors, albumin, and immunoglobulins. Treatments using PDMPs are long-term, often lifelong, therapies for chronic conditions, not acute events.
Understanding the Input: A Single Plasma Donation
The volume of plasma collected depends on the method of donation, which is either recovered from a whole blood donation or collected directly via apheresis. When a person gives whole blood, the plasma is separated afterward, yielding a smaller amount known as recovered plasma. The majority of plasma used for manufacturing is collected through apheresis.
Apheresis uses a machine to draw blood, separate the plasma, and then return the remaining components (red and white blood cells and platelets) back to the donor. This technique allows for a much larger volume of plasma to be collected in a single session, typically yielding between 625 and 880 milliliters. Because the red blood cells are returned, plasma can be donated much more frequently than whole blood, often up to twice within a seven-day period.
All collected plasma must undergo rigorous testing before it is deemed safe for therapeutic use. For fractionation, many individual donations are pooled together and then subjected to a long quarantine period. Pooling is necessary because the minute amount of a specific protein in a single donation is not sufficient to create a concentrated therapeutic dose. The final manufactured product represents a highly concentrated extract derived from thousands of liters of donated plasma.
Quantifying Treatment Needs: From Donation to Dose
The number of donations required varies dramatically between acute and chronic needs. For acute care, a patient experiencing massive blood loss may require a massive transfusion protocol. This involves transfusing four to eight units of FFP, translating to the plasma from four to eight whole blood donations, or fewer apheresis donations. The plasma requirement for acute intervention is relatively small and immediate.
The demand for chronic therapies is exponentially higher, with some patients depending on the proteins from hundreds of donations annually. For example, a single adult patient with primary immunodeficiency (PI) requires the plasma from more than 130 donations annually for Intravenous Immunoglobulin (IVIG) infusions. Patients with Alpha-1 Antitrypsin Deficiency (AATD) require weekly augmentation therapy, needing approximately 900 donations per year. The annual plasma requirement is highest for those with severe hemophilia, relying on concentrated clotting factor therapies, which takes an estimated 1,200 donations per adult patient.
These stark differences demonstrate the variability in need, ranging from a handful for a single trauma event to well over a thousand for long-term chronic care. The ongoing need for plasma is driven by the large volume of source plasma required to manufacture these concentrated, life-sustaining medications for a relatively small patient population.