Platelet donation, or apheresis, provides life-saving support for patients undergoing chemotherapy, those with blood disorders, or individuals recovering from major surgery or traumatic injuries. Because platelets have a short shelf life, often just five to seven days, a steady supply is necessary. Eligibility rules are strict, designed to protect the donor’s health and ensure the transfused product is safe and functional for the recipient.
How Specific Medications Cause Deferral
A frequent reason for temporary deferral is the recent use of certain over-the-counter medications. Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), particularly aspirin, directly impair the ability of platelets to aggregate and form clots. Aspirin causes an irreversible inactivation of the cyclooxygenase-1 (COX-1) enzyme within the platelet, preventing the production of a signaling molecule necessary for clotting.
Since aspirin’s effect lasts for the entire lifespan of the platelet, a waiting period is required until the body replaces the affected cells with new, functional platelets. Donors who have taken aspirin or any aspirin-containing medication must wait a minimum of 48 hours before donating. Other NSAIDs like piroxicam can also cause temporary deferral due to their strong antiplatelet effects.
Beyond common pain relievers, other prescription medications can lead to longer deferrals. Antiplatelet drugs, prescribed to prevent strokes or heart attacks, cause functional impairment similar to aspirin and require an extended waiting period. Certain acne medications, like isotretinoin, require a waiting period because they can pose a risk of birth defects if transfused into a pregnant recipient. Medications used to prevent HIV, such as oral pre-exposure prophylaxis (PrEP), require a three-month deferral because they may delay the detection of an HIV infection by standard screening tests.
Physiological Requirements and General Health Deferrals
Platelet donation removes only the platelet component of the blood, returning the rest of the components to the donor through apheresis. Because of this mechanical process, donors must meet certain baseline physiological standards for their safety and to ensure a usable donation. Donors must meet minimum weight requirements, typically at least 110 pounds, as this metric determines the total blood volume that can be safely processed.
A pre-screening blood test checks the donor’s cell counts, including hemoglobin and platelets. A low hemoglobin level, indicating anemia, results in a deferral to protect the donor from feeling fatigued or lightheaded after the procedure. A minimum platelet count is necessary, as the donor must have sufficient platelets to donate a therapeutic dose while maintaining a safe reserve. Generally, if the donor’s predicted post-donation platelet count would fall below 100 x 10^9/L, the donation is deferred.
Underlying chronic health conditions can also lead to a deferral to ensure the safety of the blood product. A history of certain cancers, severe heart disease, or specific autoimmune disorders may result in a permanent or long-term deferral. However, many common conditions, such as controlled diabetes or high blood pressure managed by medication, do not preclude donation, provided the condition is stable and the donor is feeling well.
Waiting Periods for Exposure and Recent Activity
Many deferrals are temporary and are based on a waiting period following an activity or exposure that carries an infectious risk. This restriction is in place because newly acquired infections may not be detectable by current screening tests during the earliest stages. For example, receiving a new tattoo or body piercing results in a deferral, typically lasting three to four months, unless the procedure was performed in a state-regulated facility using sterile, single-use equipment.
Recent travel to certain regions can cause a temporary waiting period due to the risk of vector-borne diseases like malaria or Zika virus. A trip to an area where malaria is endemic may require a 90-day waiting period to ensure the donor has not been exposed. Similarly, a donor must wait until they are fully recovered and symptom-free following a recent illness, such as a cold, influenza, or COVID-19 infection.
Regulations govern the frequency of donation to allow the body time to fully recover. Platelet donors can donate much more frequently than whole blood donors because only a fraction of the blood components are removed. A person may donate platelets as often as every seven days, though they cannot exceed 24 donations within a 12-month period. If a donor has recently received a blood transfusion, they must wait at least three months.