SAT-511 Alpha Gal Allergy in a Hypothyroid Patient

Abstract

Background: The IgE-mediated allergy to galactose-alpha-1,3-galactose (alpha-gal), a carbohydrate expressed on nonprimate mammalian proteins, has gained more clinical significance as it can present with serious, potentially fatal anaphylaxis or angioedema. In general, recognizing a specific allergy is the first step in prescribing avoidance; but with delayed symptoms, uncertain prevalence, and unclear diagnostic approach, alpha-gal allergies are difficult to recognize and prevent. To further complicate the clinical picture, some patients can tolerate small portions of nonprimate mammalian meat or tolerate one kind of meat over another. We hereby present a case that highlights the lack of guidance and resources currently available to treat a patient with alpha-gal allergy and hypothyroidism. Case Presentation: A 45-year-old woman with a history of an alpha-gal allergy and follicular thyroid neoplasm status post right hemithyroidectomy presented with postoperative hypothyroidism. After the surgery, she had undetectable serum thyroglobulin levels; her thyroid stimulating hormone (TSH) levels were ranging 5–6 µIU/mL (not on thyroid replacement). The goal was to prescribe thyroid replacement to initiate cancer suppressive strategy. The American Thyroid Association (ATA) recommends a TSH of 0.5-to-2 mcIU/mL in low risk patients postoperatively. The standard treatment of choice for correcting hypothyroidism is synthetic thyroxine (T4, levothyroxine). Commercially available levothyroxine, liothyronine, combo, and desiccated thyroid formulations - whether brand name, generic, tablet, soft gel capsule, or liquid - all contain meat byproducts and can be a concern for anaphylaxis or angioedema if one has an alpha gal allergy. Because of the possible reactions with all common formulations of thyroid hormone replacement in this patient, choosing a safe option was complicated and involved a multidisciplinary team, including allergy and immunology consultation. Daily parenteral synthetic thyroid hormone therapy was considered; however, it is not practical and was not feasible for the patient. She was eventually prescribed pure Levothyroxine, with a plant-based filler and vegetarian capsule. She tolerated this pure levothyroxine well without any adverse reactions, and the TSH goal was achieved. Conclusion: This case emphasizes the importance of recognizing various risk factors and common drugs associated with the alpha-gal allergy. Further research and pharmaceutical attention to this allergy is needed.