MON-598 Self-Reported Allergy to Thyroid Replacement Therapy: A Retrospective Chart Review

• Published in: Journal of the Endocrine Society 2019-04, Vol.3 (Supplement_1)
• Main Authors: Chamorro-Pareja, Natalia, Carrillo-Martin, Ismael, Haehn, Daniela, Westphal, Sydney, Park, Miguel, Bernet, Victor, Gonzalez-Estrada, Alexei
• Format: Article
• Language: English
• Subjects: Thyroid
• ISSN: 2472-1972; 2472-1972
• DOI: 10.1210/js.2019-MON-598

Introduction : Thyroid replacement therapy (TRT) is the treatment of choice for hypothyroidism. Levothyroxine is among the most commonly prescribed medications in the United States with over 70 million prescriptions annually. Documented hypersensitivity reactions (HSR) to TRT are rare with only a few case reports. Objectives: To determine patterns of adverse drug reactions, including hypersensitivity reactions, to TRT. Methods : A retrospective medical chart review of 11 years (2008 - 2018) identified patients with suspected HSR to TRT. HSR were defined as IgE-related symptoms secondary to TRT. Results: Of the 843 cases reviewed, 466 met our criteria. Median age was 61.2 years old; 85.8% were women, and 94.4% were Caucasian. The principal indication for TRT was primary hypothyroidism (73.6%), followed by postsurgical hypothyroidism (17.4%), and subclinical hypothyroidism (6.7%). Most patients reported a hypersensitivity reaction to the generic presentation of levothyroxine (60%), followed by Synthroid® (31.5%) and Levoxyl® (4.07%). Eighty percent of the patients reported other hypersensitivities to different medications. Non-hypersensitivity manifestations to TRT were reported more commonly than hypersensitivity manifestations (53% vs. 47%).The most frequently reported of the former were palpitations (16.4%), nausea/vomiting (9.3%), and tremor (6.3%), while rash (23.8%), hives (9.5%), and pruritus (7.1%) were the most common regarding the latter . Fifty-six percent of the patients tolerated different TRT presentations after the initial reaction. Discussion: A substantial proportion of patients with self-reported hypersensitivity reactions did not have HSR symptoms upon review of the medical record. We found that patient self-reported allergy to TRT is most likely a side effect to the medication rather than a hypersensitivity reaction. In our study, most of the patients evaluated were placed on an equally efficacious TRT presentation without further reactions. Patients may develop hypersensitivity reactions to the active ingredient, excipients, or fillers in the TRT. Patients with a suspected history of hypersensitivity reaction to TRT should undergo a thorough reaction history and when appropriate, referred for an allergy consultation.