2.1 Donor Qualification
Key Takeaways
- Every allogeneic donor must pass a health history questionnaire and a limited physical assessment (temperature, pulse, blood pressure, hemoglobin/hematocrit) before phlebotomy on each visit
- Deferrals are either temporary (the donor can return after a defined interval) or indefinite/permanent (the donor is never eligible again under current criteria), and the specialist must know which category a given finding belongs to
- Donation intervals differ by product: roughly 8 weeks for whole blood, a longer interval for double red cell collection, and much shorter intervals for plasma and platelet apheresis
- Medication deferrals are drug-specific and product-specific — a drug that defers a platelet donor for 48 hours may not affect whole blood eligibility at all
- FDA/AABB criteria are periodically revised (for example, the August 2023 move to individual risk-based donor questioning); candidates must apply the current standard in effect on their exam and not assume older numeric thresholds still apply
Donor Qualification
Quick Answer: Donor qualification is the combination of a health history questionnaire and a brief physical assessment — temperature, pulse, blood pressure, and hemoglobin/hematocrit — performed before every donation. A donor who fails any single criterion is deferred either temporarily (a defined waiting period) or indefinitely (no defined return date under current rules). The specific numeric thresholds come from FDA regulation and AABB Standards, which are revised periodically, so exam candidates should know the underlying principle behind each criterion and confirm the currently published number rather than relying on memorized figures from older sources.
Donor qualification exists to protect two people at once: the donor, who should not be harmed by giving blood, and the recipient, who should not receive a unit collected from someone unsuitable to donate. This dual-protection framework explains why some criteria (low hemoglobin, low weight) protect the donor, while others (recent tattoo, travel history, certain medications) protect the recipient.
The Pre-Donation Screen
Before each donation, every prospective donor completes a health history questionnaire (often a standardized, self-administered form such as the Donor History Questionnaire used across U.S. blood centers) and undergoes a limited physical assessment performed by trained staff. The physical assessment typically evaluates:
| Parameter | General Acceptable Range (Whole Blood) | Rationale |
|---|---|---|
| Temperature | No signs of active fever; oral temperature at or below approximately 37.5°C (99.5°F) | Fever suggests active infection; donation could worsen donor illness or, rarely, transmit a bacteremic organism |
| Pulse | Regular rhythm, generally within roughly 50–100 beats per minute (trained athletes may be assessed individually if regular and otherwise asymptomatic) | Marked bradycardia, tachycardia, or irregularity may indicate cardiac disease or predispose to a reaction |
| Blood pressure | Systolic and diastolic within limits set by the collecting facility's medical director (commonly cited as roughly ≤180 systolic and ≤100 diastolic, with a lower bound to avoid hypotension) | Uncontrolled hypertension or hypotension raises the risk of a donor reaction during or after the draw |
| Hemoglobin/Hematocrit | Minimum thresholds set separately for female and male donors, generally in the range of low-to-mid teens g/dL depending on current FDA guidance | Ensures the donor has adequate reserve to tolerate the volume removed without symptomatic anemia |
Exam strategy: Because the FDA and AABB periodically adjust the exact hemoglobin/hematocrit cutoffs and the acceptable vital-sign ranges, memorize the categories being assessed and the reason for each, and apply whatever specific number the question provides. Do not anchor to a single number you memorized from an older textbook.
Age, Weight, and Blood Volume
Minimum donor age is set by state law and facility policy (commonly 16 or 17 with or without parental consent, and 18 without restriction); there is generally no fixed upper age limit provided the donor is otherwise healthy and meets all criteria. Minimum weight for a standard-volume whole blood collection is commonly cited around 110 lb (50 kg); donors below the standard weight threshold can sometimes still donate a reduced volume calculated from their estimated blood volume, with a proportionally reduced amount of anticoagulant in the collection bag to keep the ratio correct. This weight-and-volume relationship is a favorite specialist-level concept: the anticoagulant volume in a standard bag is calibrated for a full-volume draw, so an under-filled standard bag (rather than a properly volume-adjusted low-volume bag) risks over-anticoagulating the unit.
Donation Intervals by Product
Different products draw different amounts of blood or different components, so the mandated interval before the donor may donate again varies:
- Whole blood: approximately every 8 weeks (56 days), with an annual maximum number of donations set by regulation
- Double (2-unit) red cell apheresis: a longer interval than single whole blood donation, reflecting the larger red cell volume removed
- Plasmapheresis (source/recovered plasma): a much shorter interval, often on the order of every 2 days up to a defined weekly/annual maximum, because plasma volume is replaced quickly
- Platelet apheresis: also a short interval (commonly cited around every 2 days), with an annual maximum number of platelet collections, because platelet mass regenerates faster than red cell mass
The underlying principle the exam rewards is recognizing why the interval differs: red cell mass takes weeks to regenerate, while plasma volume and platelet counts recover much faster, so the safe re-donation interval tracks the physiology of what was removed.
Temporary vs. Indefinite Deferral
A temporary deferral has a defined end date after which the donor becomes eligible again if all other criteria are met. Common temporary deferral triggers include:
- Low hemoglobin/hematocrit, low or high blood pressure, or abnormal pulse on the day of donation
- Pregnancy (deferred for a defined postpartum period)
- Recent tattoo or piercing performed at a facility not regulated to use single-use, sterile equipment (deferral commonly around 3 months; may be waived where the facility meets regulatory standards)
- Certain medications with teratogenic or infection-transmission risk — for example, isotretinoin and finasteride/dutasteride carry defined deferral periods tied to the drug's clearance from the body, because trace amounts in a transfused unit could harm a pregnant recipient or fetus
- Travel to regions with endemic malaria or other travel-associated infectious risk
- Recent receipt of certain vaccines, particularly live attenuated vaccines, which carry a defined waiting period
An indefinite (permanent) deferral has no defined return date under current criteria. Historically significant examples include a reactive/positive test result for a transfusion-transmitted infection on a prior donation, a history of certain hepatitis diagnoses after a defined age, risk factors associated with variant Creutzfeldt-Jakob disease, and a history of injection drug use not prescribed by a clinician. The exam tests whether you can correctly sort a scenario into "comes back after X" versus "does not have a defined return date" — the label "permanent" is used loosely in practice but the more precise modern term is indefinite, since criteria can be revised over time even for donors previously told they were permanently ineligible.
Medication and Aspirin Nuances
A classic specialist-level distinction: aspirin and other platelet-inhibiting medications do not defer a donor from giving whole blood, but they do defer that donor from serving as the sole source of an apheresis platelet unit for a defined short period (commonly 48 hours), because the medication impairs the function of the platelets being collected for transfusion. This illustrates a broader theme: deferral rules are not just donor-focused, they are also product-focused — the same person can be acceptable for one product and unsuitable for another on the same day, depending on what is being collected and how it will be used.
Regulatory Currency
Donor eligibility criteria are governed by FDA regulation (21 CFR 630) and refined through FDA guidance documents, implemented operationally through AABB Standards and each facility's SOPs. These have changed meaningfully over time — for example, the FDA's 2023 shift toward individual risk-based questioning replaced several prior time-based deferral categories. Specialist-level candidates are expected to apply the regulatory principle (screen for infectious risk, screen for donor safety, screen for recipient safety) and the most current published criteria, rather than assuming a number from an older reference remains unchanged.
A regular whole blood donor was found to have taken isotretinoin two weeks before presenting to donate. What is the most appropriate action?
Why does the interval required between platelet apheresis donations differ so markedly from the interval required between whole blood donations?
A donor weighing less than the standard minimum weight threshold wants to give whole blood. What is the correct approach to protect the safety of the resulting unit?