Situation: A 41-year-old man is admitted to the medical ward with weakness that began in both feet 3 days ago and has now reached his thighs. He had diarrhea 2 weeks earlier. His knee and ankle reflexes are absent, and he reports tingling in both feet. Guillain-Barré syndrome (GBS) is suspected. The provider orders intravenous immunoglobulin (IVIG). Which item in his history should the nurse report before the first infusion?

IVIG can cause anaphylaxis in people with IgA deficiency, so this history must be reported before the infusion. Other IVIG risks include headache, thrombosis, and kidney injury. Shellfish allergy, lactose intolerance, and past vaccination are not contraindications to IVIG.

Why IgA deficiency matters before IVIG

Guillain-Barré syndrome is managed with immunomodulation, and IVIG is a first-line therapy. Before the first infusion, the nurse must screen for factors that increase the risk of a severe infusion reaction. A history of selective IgA deficiency is the most important item to report because these patients can develop anaphylaxis during IVIG administration.

The mechanism involves the presence of anti-IgA antibodies of the IgG or IgE class in some IgA-deficient individuals. When IVIG, which contains small amounts of IgA, is infused, these preformed antibodies can trigger an immediate hypersensitivity reaction ^[1][3]. Life-threatening anaphylaxis occurs very rarely overall, but it is disproportionately reported in IgA-deficient patients who have anti-IgA antibodies. ^[4]

It is important to recognize that not every person with IgA deficiency will react. The association between anti-IgA antibodies and severe reactions has been inconsistent across reports, and a variety of product- and patient-related factors may influence whether a reaction occurs ^[3]. However, because the consequence can be life-threatening, Key point! the nurse must identify and report this history before the infusion begins so the provider can select an IgA-depleted product or plan alternative therapy.

How this fits with other IVIG risks

IVIG is generally well tolerated, but adverse effects are common. Up to 40% of intravenous IgG infusions may be associated with some adverse effect, though most are mild and not serious ^[2]. The most frequent infusion-related complaint is headache ^[2]. Other mild reactions include flushing, low backache, nausea, and wheezing ^[4].

Many of these milder reactions are related to the rate of infusion. Slowing the infusion rate often prevents or rapidly relieves these non-anaphylactic reactions. ^[2][4] This is a practical nursing intervention: if a patient develops headache or flushing during IVIG, the first action is typically to slow or temporarily stop the infusion, not to assume anaphylaxis.

More serious reactions, including true anaphylaxis and anaphylactoid reactions, occur less frequently ^[2]. The nurse should distinguish between rate-related discomfort and signs of a true hypersensitivity emergency such as hypotension, bronchospasm, or angioedema.

Why the other options are not contraindications

History item	Relevance to IVIG	Nursing implication
Lactose intolerance diagnosed as a teenager	IVIG products are not a meaningful source of lactose; this does not predict an infusion reaction	No need to withhold or modify IVIG for this reason
Allergy to shrimp and crab since childhood	Shellfish allergy is an allergy to tropomyosin proteins, not to immunoglobulins; it is not a contraindication to IVIG	No cross-reactivity with IVIG; document but proceed with routine monitoring
Influenza vaccination received 1 year ago	Prior vaccination does not increase the risk of IVIG-related anaphylaxis	No contraindication; vaccination history is unrelated to this infusion decision
Known IgA deficiency	Associated with rare but life-threatening anaphylaxis due to anti-IgA antibodies [1][3][4]	Watch out! Report before infusion; provider may choose IgA-depleted product or alternative therapy

Clinical priority for the nurse

The nursing priority before the first IVIG infusion is to identify risk factors for the most dangerous adverse event, which is anaphylaxis. A known IgA deficiency is the one item in this history that directly raises the risk of a life-threatening reaction and therefore must be communicated to the provider before the infusion starts. Shellfish allergy, lactose intolerance, and remote vaccination do not carry the same implication and do not require withholding IVIG.