A transfusion medicine physician in Hawaii reports that a donor center in Oahu is currently deferring all donors, both whole blood and apheresis, who are taking an ACE-inhibitor regardless of the diagnosis. He wonders if other centers are also deferring donors who are taking ACE inhibitors, regardless of diagnosis?

The following comments have been received.

ADDENDA Nov. 21, 2006

1. According to Dr. Ted Eastlund of the University of Minnesota Medical School (attribution used with permission), some transfusion recipients of bedside filtered platelets have experienced acute hypotension and some studies have shown:

1. Bradykinin can be released from high molecular weight kininogen in the platelet donor plasma undergoing contact activation through negatively-charged filters
2. In most recipients, even those on Angiotensin Converting Enzyme Inhibitors (ACEi), the bradykinin is short-lived being cleaved by plasma kininases and they do not have hypotension. One of the major kininases in plasma is blocked by the ACEi but another one (aminopeptidase P) remains to effectively catabolize the bradykinin, and as a result there is no hypotension or vasodilation-facial flushing.
3. However, in some patients who are on an ACEi and have a relative deficiency of the kininase: aminopeptidase P (~ 5% of the population), the bradykinin has a prolonged half-life and can cause hypotension.

Thus it is an issue of recipients taking ACEi and not an issue of donors taking ACEi. In the US, the Red Cross does not defer donors on ACEi.

There is one kind of donor who may be a possible exception to this. Theoretically, a plateletpheresis donor taking an ACEi might be at risk if the donor blood is exposed to negatively-charged materials in the extracorporeal circuit. There have been published articles describing patients on ACEi undergoing dialysis, liposorber therapy to reduce lipids and staphylococcal protein A column therapy who have had bradykinin-related hypotensive reactions caused by this pathophysiology. Dr. Eastlund observed one plasma exchange patient on ACEi who had the typical red face and acute hypotension that stopped each time we stopped the reinfusion but we didn't document the kininase abnormality in her.

Dr. Eastlund doesn't recommend exclusion of whole blood or apheresis donors who are taking ACEi.

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Ira A. Shulman, MD
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W. Tait Stevens, MD
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