Platelets, also known as thrombocytes, are tiny cell fragments in the blood that are fundamental to the body’s ability to stop bleeding. These cells rush to the site of an injury, sticking together and forming a plug to initiate the clotting process. Because platelets have a short shelf life—typically only five to seven days—the supply must be constantly replenished by volunteer donors. Patients undergoing chemotherapy often experience severely low platelet counts, making them highly dependent on transfusions to prevent hemorrhages. Platelets are also used for trauma victims and during major surgical procedures, making a consistent donor pool necessary.
Determining Your Eligibility
Most donation centers require a platelet donor to be in good general health and feeling well on the day of the appointment. A baseline requirement for donation is a minimum weight of 110 pounds and being at least 16 or 17 years old, depending on the state and specific center policies. Unlike whole blood donation, the eligibility criteria for platelets are often more stringent because of the specialized collection process and the high demand.
A specific deferral relates to medications, particularly NSAIDs like aspirin. Donors must avoid taking aspirin or any aspirin-containing products for at least 48 hours before their appointment. These medications irreversibly interfere with the ability of platelets to aggregate and function properly, compromising the quality of the donated product. Other common pain relievers, such as acetaminophen, generally do not affect platelet function and are acceptable to take.
A donor’s recent medical history is reviewed, including vaccinations and international travel. While most common vaccines, such as those for influenza or COVID-19, do not require a waiting period if the donor is symptom-free, others like the MMR or Yellow Fever vaccine may require a two- to four-week deferral. Travel to areas where certain infectious diseases, such as malaria, are endemic may also result in a temporary deferral period. A comprehensive screening process, including a medical history questionnaire and a mini physical, is performed to confirm eligibility.
The Platelet Donation Process
Platelet donation uses a specialized technique called apheresis, which allows a machine to separate blood components. The process begins with the insertion of a sterile needle, usually into an arm vein, which draws a small amount of blood into the apheresis machine. Inside this device, the blood is spun using centrifugation, a process that separates the blood into its constituent parts based on density.
The machine then collects only the platelets, along with some plasma, and returns the remaining components—red blood cells and white blood cells—to the donor. This cyclical drawing and returning of blood means the donor loses only a small volume of red blood cells, which is why platelet donation can be done more frequently than whole blood donation. The entire procedure is performed while the donor is comfortably seated, and it typically takes between 90 and 120 minutes to complete.
To prevent the blood from clotting inside the machine’s tubing, an anticoagulant, most commonly citrate, is introduced into the drawn blood. Citrate works by temporarily binding to calcium ions in the blood, an action necessary for the clotting cascade. As the citrated blood is returned, some individuals may experience a mild side effect known as paresthesia, which is a tingling sensation around the lips or fingertips. This sensation is caused by the temporary reduction in ionized calcium levels and is managed by the donation staff, sometimes with a calcium supplement.
Preparing for Donation and Recovery
Preparation for a platelet donation impacts the success and quality of the collection. Hydration is recommended in the 24 hours leading up to the appointment, as being well-hydrated makes the veins more prominent and helps the apheresis process flow smoothly. Donors should also eat a healthy, non-fatty meal before arriving, as high-fat foods can cause lipemia, which may interfere with the separation of the platelets.
After the procedure is complete, donors are encouraged to remain in the center for a brief period to rest and consume fluids and a snack. The body replaces the collected volume of plasma and fluid within 24 hours, and the platelet count returns to baseline quickly, often within 48 hours. Most donors can resume normal activity, though it is often advised to avoid heavy lifting or strenuous exercise with the donation arm for several hours.
The rapid replenishment of platelets allows for a shorter interval between donations compared to whole blood. A healthy, eligible donor may donate platelets as frequently as every seven days, up to a maximum of 24 times within a rolling twelve-month period. This high frequency is important for maintaining the supply, as a single apheresis donation can yield the equivalent of several whole-blood-derived platelet units, helping multiple patients with one visit.