Plasma is the liquid portion of your blood, and it serves two broad purposes: inside your body, it transports nutrients, hormones, and clotting proteins to where they’re needed. Outside your body, donated plasma is used to manufacture life-saving treatments for burn victims, trauma patients, and people with rare diseases like hemophilia and immune deficiencies. It makes up about 55% of your total blood volume and is roughly 91% to 92% water, with the remaining 8% to 9% consisting of dissolved proteins, salts, and other solids that keep you alive.
What Plasma Does Inside Your Body
Plasma is essentially the river system of your bloodstream. Red blood cells, white blood cells, and platelets all float suspended in it, but plasma itself carries dissolved cargo those cells cannot: hormones from your glands to their target organs, glucose and fats from digestion to your muscles and tissues, and waste products to your kidneys and liver for disposal.
Two key proteins in plasma handle much of the heavy lifting. Albumin, the most abundant plasma protein (normally 3.5 to 5 g/dL in a healthy adult), acts like a sponge that holds water inside your blood vessels. It maintains what’s called osmotic pressure, roughly 25 mmHg, which prevents fluid from leaking out into surrounding tissues. When albumin levels drop, fluid seeps into places it shouldn’t be, causing swelling. Globulins, the second major protein group (normally 2.3 to 3.4 g/dL), include antibodies that fight infection and transport proteins that carry iron, vitamins, and other molecules through the bloodstream.
Plasma also contains fibrinogen and other clotting factors. When you cut yourself, these proteins activate in a chain reaction that forms a mesh-like clot over the wound. Without adequate clotting factors in your plasma, even minor injuries can lead to dangerous bleeding.
Emergency and Trauma Medicine
In hospitals, plasma transfusions are a frontline treatment when someone is losing blood fast. Trauma patients and people with severe burns both develop a condition where the lining of their blood vessels breaks down, allowing fluid to escape into surrounding tissue. This makes it difficult to maintain blood pressure and organ function even when fluids are being pumped in.
Plasma helps because it’s not just volume. Unlike saline, which only adds water and salt, plasma contains the proteins that stabilize damaged blood vessel walls. For major trauma, current protocols call for transfusing plasma alongside red blood cells in roughly equal amounts. Burn patients present a particular challenge because the burn wound triggers an intense inflammatory response on top of the fluid loss. Research from burn centers has shown that plasma is a better resuscitation fluid for significant burns precisely because it addresses both problems at once: restoring lost volume and repairing the vessel lining that’s allowing fluid to leak.
Treatments Made From Donated Plasma
Beyond direct transfusions, plasma is the raw material for an entire category of medicines called plasma-derived products. Manufacturing facilities take pooled donations, sometimes from over a thousand donors per batch, and separate plasma into its individual therapeutic proteins through a process called fractionation.
Fractionation works in stages. First, frozen plasma is slowly thawed to just above freezing, which causes certain proteins, particularly clotting factors like Factor VIII and fibrinogen, to precipitate out as a thick paste called cryoprecipitate. The remaining liquid then goes through successive rounds of cold ethanol precipitation at carefully controlled temperatures (as low as negative 6°C), pH levels, and protein concentrations. Each round causes a different group of proteins to clump together and drop out of solution. These are collected by centrifuge or filtration. Further purification using chromatography improves the purity of each product, and dedicated viral reduction steps, including nanofiltration through membranes as fine as 15 nanometers, ensure safety.
The resulting medicines treat conditions across several categories:
- Immune deficiencies. People born with primary immune deficiency don’t produce enough antibodies on their own. Immunoglobulin concentrates extracted from plasma provide a broad spectrum of antibodies collected from the donor pool, essentially giving these patients a borrowed immune system. The same immunoglobulin, given at higher doses, also has anti-inflammatory effects and is used for certain neurological, blood, and skin disorders.
- Bleeding disorders. Hemophilia A and B result from missing clotting factors (Factor VIII and Factor IX, respectively). Plasma-derived concentrates of these factors allow patients to prevent or stop bleeding episodes. In many countries, these remain the standard treatment.
- Other rare conditions. Plasma yields proteins like alpha-1 antitrypsin (for a genetic lung disease) and C1-esterase inhibitor (for hereditary angioedema, a condition causing severe swelling). Many of these conditions affect fewer than 5 in 10,000 people, making plasma-derived medicines true orphan drugs with no practical alternatives for some patients.
Donating Plasma vs. Whole Blood
Plasma donation uses a process called plasmapheresis, which is quite different from giving whole blood. A machine draws your blood, spins out the plasma, and returns your red blood cells and platelets back to you along with saline. Because you keep your red cells, recovery is faster: you can donate plasma again in as few as 6 days, compared to the 56-day wait required between whole blood donations.
The tradeoff is time. A whole blood donation takes about 15 minutes of actual draw time. Plasmapheresis takes a minimum of 45 minutes because of the separation and return cycles. The demand for plasma is enormous and growing, driven largely by the increasing use of immunoglobulin therapies worldwide. A single batch of immunoglobulin requires donations from over a thousand people, which is why plasma collection centers operate at high volume year-round.
How Plasma Is Stored
Once collected for medical use, plasma must be frozen at negative 18°C or colder. Fresh frozen plasma, the type used in emergency transfusions, is frozen within 8 hours of collection to preserve its full complement of clotting factors. Stored at that temperature, it has a shelf life of one year. Other plasma products frozen within 24 hours follow the same storage requirements and expiration timeline. Once thawed for use, plasma must be transfused relatively quickly, as clotting factors begin to degrade at room temperature.