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What Is Plasma?

Plasma is the often forgotten component of blood. White blood cells, red blood cells, and platelets are essential to body function, but plasma also plays a crucial, and mostly unrecognized, job, carrying these blood components throughout the body as the fluid in which they travel.

Illustration of blood components
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Facts about plasma

Plasma is the largest component of your blood, making up about 55 percent of its overall content. When isolated on its own, blood plasma is a light yellow liquid, similar to the color of straw. Along with water, plasma carries salts and enzymes.

The primary purpose of plasma is to transport nutrients, hormones, and proteins to the parts of the body that need it. Cells also deposit their waste products into the plasma, and the plasma in turn helps remove this waste from the body. Blood plasma also ushers the movement of all the elements of blood through the circulatory system.

Plasma's importance to your health

Plasma is a critical component in the treatment of many serious health problems. This is why there are frequent blood drives encouraging people to donate blood plasma.

Along with water, salt, and enzymes, human plasma also contains important components, such as immunoglobulins (antibodies), clotting factors, and the proteins albumin and fibrinogen. When you donate blood, health professionals can isolate these vital ingredients from your plasma and concentrate them into various products. These products are then used as treatments that can potentially help save the lives of people suffering from burns, shock, trauma, and other medical emergencies.

The proteins and antibodies in plasma are also used to create therapies for rare chronic conditions, such as autoimmune disorders and hemophilia. With access to these treatments, people with these conditions can live long and productive lives. In fact, some health organizations call plasma "the gift of life."

Donating plasma

If you want to donate plasma to help others in need, you will go through a screening process beforehand to make sure your blood is healthy and safe. If you qualify as a plasma donor, you'll spend about an hour and a half at a clinic on every subsequent visit.

During the actual blood donation process, your blood is drawn through a needle placed in a vein in one arm. Then a special machine separates the plasma (and often the platelets) from your blood sample. This process is called plasmapheresis. The remaining red blood cells and other blood components are then returned to your body, along with a little saline (salt) solution.

People with the blood type AB are in the greatest demand for plasma donation. Though they make up just 4 percent of the population, their plasma is universal, which means it can be used by anyone.

At noncommercial donation sites, people can donate plasma every 28 days, up to 13 times a year. To learn more about donating blood, visit the American Red Cross website

Online Medical Reviewer: Bowers, Nancy, RN, BSN, MPH
Online Medical Reviewer: newMentor board-certified, academically affiliated clinician
Date Last Reviewed: 8/14/2013
© 2000-2014 Krames StayWell, 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.