MON-147 Progesterone Hypersensitivity Manifesting as Cyclical Urticaria

Abstract Disclosure: D.R. Vangipuram: None. A. Abidov: None. M. Correia: None. A. Wahba: None. Introduction: Progesterone hypersensitivity is a rare condition characterized by cutaneous and/or systemic allergic reactions that correlate with elevated levels of progesterone. The progesterone could be endogenous, during the luteal phase of the menstrual cycle, or due to exogenous administration. This case details the presentation, management, and outcome of a 41-year-old female with cyclical urticaria due to progesterone. Case Report: A 41-year-old female presented with a history of recurrent urticaria that initially appeared cyclical, and became significantly worse following the insertion of a levonorgestrel-containing contraceptive device for abnormal uterine bleeding (AUB). The cyclical nature of her symptoms suggested a hormonal component and progesterone hypersensitivity was considered a potential diagnosis. The lipid carrier compound in available progesterone products is highly irritating to the skin, leading to higher false positive rates on skin testing. A leuprolide-induced progesterone suppression test, a diagnostic procedure involving leuprolide administration to suppress endogenous progesterone production, was performed instead. After the removal of the levonorgestrel-containing contraceptive device, the patient received three doses of leuprolide, each administered monthly at a dose of 7.5 mg intramuscularly. Three months after the initiation of leuprolide therapy, the patient's progesterone levels were measured at less than 0.2 ng/mL. The patient then reported significant improvement in her symptoms, indicating a high likelihood of progesterone hypersensitivity. The patient subsequently got three additional intramuscular doses of 7.5 mg of leuprolide monthly as bridging therapy, following which she underwent a total laparoscopic hysterectomy and bilateral salpingo-ophorectomy. The patient had no further recurrence of her symptoms after the surgery, further confirming the role played by progesterone in this condition. Conclusion: Progesterone hypersensitivity should be considered in the differential diagnosis of cyclical urticaria/allergic reactions, especially if they are noticed to occur in the luteal phase of the menstrual cycle. Presentation: Monday, July 14, 2025