Immunoglobulin A (IgA) deficiency

Resources

In the event of a discrepancy between the information on this page and what is in the Circular of information, the latter will take precedence.

Immunoglobulin A (IgA) deficiency is the most common human immune deficiency. IgA deficiency is determined by measuring the IgA immunoglobulin concentration in the blood. The normal IgA concentration is 0.8 to 4 mg/mL. The IgA deficiency criterion is a value less than 500 mg/mL (<0.05mg/dL), or a value roughly 2 to 5,000 times lower than normal. The prevalence of IgA deficiency in the population is roughly 1 in 500.

Most people with IgA deficiency are asymptomatic, but some are more prone to respiratory and gastrointestinal infections. During transfusion, the presence of anti-IgA antibodies in an IgA-deficient patient can cause a severe allergic reaction.

In blood products, the IgA level can be lowered by washing the packed red blood cells.

People with a history of severe allergic reaction after a transfusion AND who have anti-IgA antibodies should receive transfusions of red blood cells without IgA or washed red blood cells that have shown sufficiently low IgA levels (less than 0.05 mg/dL, or 0.5 mg/L).

Platelets, plasma or cryoprecipitates should not be transfused unless they are free of IgA.

For plasma, it is desirable to have in the inventory products with no IgA and compatible ABOs for deficient patients with a history of severe transfusion reaction.
For platelets, given the short lifespan, donors whose status as IgA deficient has been determined are called upon for one-time donations.

Action

The purpose of transfusing blood products low in IgA is to prevent a severe allergic reaction after transfusion in IgA-deficient recipients who have previously had this type a reaction.

Principales indications

The use of blood products without IgA should be considered only for patients with IgA deficiency and with a history of severe allergic transfusion reaction.

It is appropriate to find out the patient’s status when IgA deficiency is suspected.

It should be noted that, if the patient’s status has not been confirmed as IgA deficient by Héma-Québec, you can send the patient’s samples to Héma-Québec, along with the Requête pour dosage IgA (in French only).