Abstract Disclosure: T. Avanessian: None. H. Alsamarraie: None. Background: Physiologic changes, including changes in the HPA axis and RAAS, during pregnancy pose challenges in the management of adrenal insufficiency in pregnant women. This case report discusses the management of adrenal insufficiency in a young primigravida female with Addison’s disease. Clinical Case: At 19.5 weeks of gestation, a 26-year-old primigravida, previously diagnosed with Addison’s disease 5 years ago, presented to an acute care center for syncopal episodes. The pregnancy had been complicated by persistent nausea and vomiting, labeled as hyperemesis gravidarum, and recurrent syncopal episodes, resulting in 6 ED visits and 3 hospitalizations, with symptoms improving each time after IV hydration and then returning within a few days. At presentation, the patient reported lightheadedness, sweating, palpitations, dyspnea, fatigue, nausea, vomiting, and a 10 lb weight loss since the beginning of pregnancy. The pre-pregnancy regimen was hydrocortisone 10 mg in the morning and 5 mg in the afternoon, with fludrocortisone 0.1mg daily. At 8 weeks of gestation, due to increased fatigue and hypotension, the hydrocortisone dose was doubled, while fludrocortisone was continued the same. During admission, blood pressure ranged from 67/37 to 90/56 mmHg, and heart rate ranged between 93-103 bpm. On labs, electrolytes were normal, and the serum renin level was elevated at 5.803 ng/ml/hr (0.167-5.380). Treatment included IV hydration and hydrocortisone 40 mg in the morning and 20 mg in the afternoon. Despite symptom improvement, blood pressure remained low. Thus, fludrocortisone was increased to 0.1 mg twice daily. Within 3 days, all symptoms improved, allowing for the down-titration of the hydrocortisone dose. The patient was discharged with hydrocortisone 30 mg at 8 AM, 10 mg at 3 PM, 5 mg at 7 PM, and fludrocortisone at 0.1 mg twice daily. Conclusion: Managing symptoms of adrenal insufficiency during pregnancy is challenging due to the overlap of symptoms and signs with physiologic manifestations of pregnancy. The use of biochemical testing is limited, given the physiological activation of RAAS and progressive increases in renin, CRH, ACTH (from both pituitary and placental sources), and cortisol during pregnancy. Monitoring mineralocorticoid requirements is further complicated by physiological changes in blood pressure and interstitial fluid status. While some literature suggests that adjusting fludrocortisone may not be necessary, as an increase in glucocorticoid dose can compensate, determining the correct dose of glucocorticoid and mineralocorticoid replacement should be tailored to each patient and their specific symptoms.