Which is a known contraindication for blood transfusion?

The presence of a known severe allergic reaction is considered a contraindication for blood transfusion because it raises significant safety concerns for the recipient. If a donor has a history of severe allergic reactions to blood products, there is a risk that their blood may cause similar reactions in patients receiving the transfusion. Severe allergic reactions can lead to adverse events, such as anaphylaxis, which can be life-threatening. Therefore, to ensure the safety and well-being of patients, blood centers are vigilant in screening donors, and any history of severe allergic reactions is a key factor in determining donor eligibility for blood donations.

In contrast, low iron levels in the donor are monitored, but they generally do not exclude a donor from donating blood as long as they meet the minimum hemoglobin requirements at the time of donation. High cholesterol levels typically do not affect the suitability of a blood donation, as cholesterol levels are not linked to transfusion reactions. Lastly, the age of a donor over 60 does not usually preclude them from donating blood, provided they meet other health criteria. Overall, the focus is on the safety of the recipient, which is why known severe allergic reactions are treated seriously.