Porcine heparin allergy in a pork allergic patient: A case report

Abstract

RATIONALE: Immediate hypersensitivity reactions to intravenous heparin are uncommon, but have occurred, with life-threatening results. Food allergy to pork has not previously been implicated in these reactions, to our knowledge. We report on a patient with pork allergy and a positive skin test to porcine heparin.METHODS: A 61-year old patient with self-identified allergy to beef and pork was admitted for coronary artery bypass surgery. This patient had suffered from chronic urticaria three years prior to admission, which resolved when he discontinued ingestion of both of these meats. Within the previous year he had tried to reintroduce pork in a pizza topping, producing urticaria with shortness of breath and chest tightness which necessitated treatment in the emergency department. Prior to CABG he expressed concern about the origins of the pork-derived heparin which was to be used for anticoagulation, and the allergy service was consulted. We performed skin testing to heparin.RESULTS: Intradermal testing resulted in a 12 mm wheal with 15 mm of erythema, a positive result compared to the saline negative control (5 mm wheal/no erythema). Histamine control produced 12 mm wheal and 50 mm erythema. No other heparin formulation was available and it was deemed the optimal choice for anticoagulation by the cardiothoracic surgical team. Therefore the patient was desensitized to heparin in the intensive care unit prior to surgery, and underwent CABG with satisfactory results.CONCLUSIONS: Allergy to pork may result in IgE-mediated responses to porcine-derived medications such as heparin. Patients and physicians should be aware of this potential reactivity. RATIONALE: Immediate hypersensitivity reactions to intravenous heparin are uncommon, but have occurred, with life-threatening results. Food allergy to pork has not previously been implicated in these reactions, to our knowledge. We report on a patient with pork allergy and a positive skin test to porcine heparin. METHODS: A 61-year old patient with self-identified allergy to beef and pork was admitted for coronary artery bypass surgery. This patient had suffered from chronic urticaria three years prior to admission, which resolved when he discontinued ingestion of both of these meats. Within the previous year he had tried to reintroduce pork in a pizza topping, producing urticaria with shortness of breath and chest tightness which necessitated treatment in the emergency department. Prior to CABG he expressed concern about the origins of the pork-derived heparin which was to be used for anticoagulation, and the allergy service was consulted. We performed skin testing to heparin. RESULTS: Intradermal testing resulted in a 12 mm wheal with 15 mm of erythema, a positive result compared to the saline negative control (5 mm wheal/no erythema). Histamine control produced 12 mm wheal and 50 mm erythema. No other heparin formulation was available and it was deemed the optimal choice for anticoagulation by the cardiothoracic surgical team. Therefore the patient was desensitized to heparin in the intensive care unit prior to surgery, and underwent CABG with satisfactory results. CONCLUSIONS: Allergy to pork may result in IgE-mediated responses to porcine-derived medications such as heparin. Patients and physicians should be aware of this potential reactivity.