FRI190 Catching A Chimera: A Case Of Suspected Glucocorticoid Remediable Aldosteronism

Disclosure: A. Khan: None. B. Ramchandani: None. H.B. Aftab: None. Introduction: Familial hyperaldosteronism type 1 (FH-I), also known as glucocorticoid remediable aldosteronism (GRA) is responsible for 1% of cases of primary aldosteronism (PA). It is caused by a chimeric fusion of the CYP11B2 and CYP11B1 genes resulting in ACTH-sensitive aldosterone production. We describe a case of suspected GRA and outline the diagnosis of this rare condition. Case. A 52-year-old female with history of type 2 diabetes mellitus, obesity, sleep apnea, SVT with ablation presented with long-standing history of resistant hypertension (HTN). HTN was diagnosed in her late twenties. She was previously trialed on eight different classes of antihypertensive medications excluding mineralocorticoid antagonists or potassium-sparing diuretics but HTN remained uncontrolled. Current regimen included hydralazine, nebivolol, and furosemide. Her sister had HTN diagnosed in her forties, a nephew with HTN diagnosed in his early twenties and mother with HTN with unclear age of diagnosis. Her systolic and diastolic BP averaged 150 mmHg and 90 mmHg, respectively, on both home and clinic monitoring. Physical examination was significant for mild cushingoid appearance. Screening tests for pheochromocytoma and hypercortisolism were normal. Plasma aldosterone concentration (PAC) was noted to be at 14.4 ng/dl (<39.2) with a plasma renin activity (PRA) of <0.6 ng/mL/h (2.9 - 10.8), with aldosterone to renin ratio (ARR) of 24. Repeat testing showed PAC of 15.1 ng/dl, PRA<0.6 ng/ml/hr (ARR: 25.1) with potassium of 3.3 mmol/L (3.5 -5.1). PAC levels remained unsuppressed above 10 ng/dL following four-hour, seated, 2 L IV saline suppression test with serum potassium of 3.5 mmol/L. CT abdomen showed normal appearance of the adrenal glands. Given early age of onset of HTN and strong family history, 3-day dexamethasone test was performed using 1 mg oral dexamethasone every 12 hours following which PAC suppressed to <1 ng/dl. Patient was started on spironolactone 25 mg twice daily and at the time of writing is awaiting genetic testing to confirm the diagnosis of GRA. Discussion: GRA is a rare subtype of PA which has an increased risk of cardiovascular and cerebrovascular complications. Our case highlights the importance of screening for GRA in patients who have a personal and/or family history of early onset HTN who have screened positive for PA. Genetic testing for chimeric CYP11B1/B2 gene is the confirmatory step of diagnosis, however, a 3-day dexamethasone suppression test can be used to screen for GRA with a high sensitivity. Elevated levels of urine 18-hydroxycortisol and 18-oxocortisol are also noted but these are not widely available tests. Treatment of GRA is with medical management only; since surgical intervention is not required; proper diagnosis can also save the patient from unnecessary and invasive tests such as adrenal vein sampling. Presentation: Friday, June 16, 2023