SUN-205 Beyond Hypoglycemia: Type I Glycogen Storage Disease with Endocrine, Hematologic, and Renal Involvement

Abstract Disclosure: M. Rivera-López: None. M.B. Bojalil: None. M. Aguilar-Soto: None. F.J. Gomez-Perez: None. J.A. Puentes-López: None. We present the case of an 18-year-old woman from Puebla, México referred from a pediatric hospital to the Endocrinology department. She had a history of seizures at the age of one, initially attributed to a motor vehicle accident. During hospitalization for pneumonia, she was found to have hypoglycemia, hypertriglyceridemia, and hepatomegaly, prompting a liver biopsy. Histopathological analysis revealed uniform panlobular involvement characterized by cytoplasmic expansion with preserved central nuclear positioning, plasma membrane reinforcement, and prominent nuclear glycogenation. The cytoplasm showed strong PAS staining, which disappeared with diastase treatment, with only mild fibrosis. These findings were initially reported as consistent with type III glycogen storage disease (GSD). She was subsequently managed with cornstarch and soy milk.From the age of four, she experienced multiple episodes of bleeding at various sites following minor trauma. At 14, she had an acute gout episode and was started on allopurinol. Menarche occurred at 15, with irregular cycles and polymenorrhea. At 17, she developed neck swelling, and a private physician diagnosed autoimmune hypothyroidism with positive thyroid antibodies, initiating levothyroxine at 50 mcg daily.Following her first consultation in the Endocrinology department, a FreeStyle Libre sensor was placed for 14 days, revealing the following metrics: mean glucose of 90 mg/dL, time in range 74%, high 0%, low 26%, very low 0%, with a total of 23 hypoglycemic events. During examination, features like thin limbs, doll-face and hepatomegaly were documented. Hematology evaluation confirmed type 2 von Willebrand disease, with a ristocetin cofactor activity-to-antigen ratio < 0.7, indicating reduced functional activity relative to antigen levels. During the diagnostic workup, nephrotic-range proteinuria was detected, leading to a renal biopsy that revealed focal segmental glomerulosclerosis, with 83% global glomerulosclerosis, 60% interstitial fibrosis, and 50% tubular atrophy. Treatment with losartan and empagliflozin was initiated.Given the clinical course and histopathological findings, the patient was reclassified as having type I glycogen storage disease. An increased prevalence of autoimmune hypothyroidism has been reported in GSD type I, along with qualitative von Willebrand factor abnormalities and glomerulosclerosis, which rarely present as overt nephrotic syndrome.She remains under multidisciplinary management and has been referred for close nutritional follow-up. This case illustrates the complexity of metabolic disorders and the need for a thorough diagnostic approach. Presentation: Sunday, July 13, 2025