ODP043 Hypokalemia in Autoimmune Polyglandular Syndrome: A Case of Newfound Type I (Distal) Renal Tubular Acidosis

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy Type 1 (APECED) is a rare autosomal recessive disorder predisposing to early development of chronic mucosal candidiasis and progressive development of various endocrinopathies, such as Addison's disease, Primary Hypoparathyroidism, and Type 1 Diabetes (T1D). Few cases described in literature regarding renal involvement in this disorder, with most common manifestation being tubulo-interstitial nephritis, however, there is limited evidence regarding presentation of APECED with hypokalemia due to concomitant Type I Renal Tubular Acidosis (RTA). Case of a 47-year-old female with past medical history of APECED Type 1 (consisting of hypoparathyroidism, adrenal insufficiency, and chronic mucocutaneos candidiasis), T1DM on honeymoon, hypothyroidism, and nephrolithiasis presenting to the emergency department complaining of bilateral upper and lower extremity weakness of one week in evolution, but worsening on day of admission. Denies associated constitutional symptoms. Strong positive first-degree relative history for autoimmune diseases. Physical examination: 2/5 strength in all four extremities, deep tendon reflexes grossly intact, no gross sensory or motor deficits. Patient on oral steroid therapy for her Addison's, calcitriol supplementation for hypoparathyroidism, and potassium chloride supplementation since a prior hypokalemic episode 17 years ago. Laboratory workup results remarkable for sodium: 140 mmol/L (N: 135-144 mmol/L), chloride: 110 mmol/L (N: 95-105 mmol/L), potassium: 2. 0 mmol/L (N: 3.4-4.5 mmol/L), central bicarbonate: 18mmol/L (N: 23-31 mmol / L), anion gap: 12 (N: 10-12), glycosylated hemoglobin: 5.2% (N: 4.7-6.2%) and anti-glutamic acid decarboxylase antibodies >25,000 U/mL (N: <5 U/mL). Adrenal insufficiency was ruled out by laboratory findings, but she had normal anion gap metabolic acidosis (NAGMA) and hypokalemia. Urinalysis was negative for urinary tract infection but with pH: 7. 0 (N: 4.5-8. 0). Urine spots, measured to find the cause of her NAGMA, showed urine sodium: 92 mmol/L, urine potassium: 10 mmol/L, urine chloride: 90 mmol/L, and urine anion gap of 12 mEq/L, which is positive and suggests low urinary NH4+, consistent with Type I (Distal) RTA as the main etiology. Patient started on IV potassium replacement, which increased potassium to 3.8 mmol/L, and improved acidotic state, with central bicarbonate of 29mmol/L, and overall symptoms. Patient was discharged home with alkali therapy (Sodium citrate) for Type I (Distal) RTA. RTA is an underrecognized condition that may be inherited or acquired. Diagnosis is difficult but can be verified with a thoughtful workup. RTA should be considered for any patient with otherwise unexplained hyperchloremic metabolic acidosis and may be the presenting manifestation of autoimmune diseases. Regular renal monitoring for any APECED patient should be performed. We present this case as evidence for the coexistence of several different immune-mediated diseases in the clinical context of APECED with an unusual concomitant Type I (Distal) RTA, where there is few documented evidence of association with this disorder. Presentation: No date and time listed