A Case of Prolonged Glycosuria Secondary to SLC5A2 Receptor Mutation Affecting theSGLT2

Introduction: Glycosuria most commonly occurs in diabetics patients but can also be seen in pregnancy, multiple myeloma, secondary to SGLT2 inhibitor use or with any medication that causes proximal renal tubular acidosis for e.g. Tenofovir. Here we present a case of glycosuria secondary to a mutation in the SLC5A2 receptor, encoding the sodium-glucose cotransporter 2 (SGLT2). Case Description: A 38-year-old with a past medical history of hypothyroidism presented with persistent glucosuria despite normoglycemia on routine lab work. The patient was Initially evaluated by urology for recurrent yeast infections. Subsequent workup was unremarkable, and the patient was referred to nephrology for persistent glycosuria. Patient denied any personal history of diabetes (HBA1c of 5.1%) and Levothyroxine was the only home medication for underlying hypothyroidism. Persistent lab work was notable for normal serum glucose and isolated glucosuria on the urine analysis. Subsequent workup for glycosuria was negative for serum protein electrophoresis (SPEP), free light chains, anti-nuclear antibody (ANA), ruling out concerns for multiple myeloma and connective tissue disease. The patient did not have any electrolyte abnormalities for e.g., hyperphosphatemia, hyperuricemia, or acidosis to suggest proximal Renal tubular acidosis (RTA) or Fanconi’s syndrome. Renal ultrasound showed normal kidneys without cysts, hydronephrosis or stones. With work up so far negative for any disease process, there was concern for familial renal glycosuria (FRG). For patient reassurance it was decided to go ahead with genetic testing which confirmed an autosomal dominant/recessive mutation of the SLC5A2 gene. Management primarily involved patient reassurance and dietary modifications including a low carb diet as uncontrolled glycosuria would lead to recurrent yeast infections. Discussion: This case underlines the importance of considering genetic causes of glycosuria in the absence of diabetes mellitus and other common causes. Accurate diagnosis through genetic testing can spare patients from unnecessary treatments and anxiety associated with a potential misdiagnosis. Additionally, it highlights the significance of genetic counseling and screening for affected individuals, allowing patients to understand their carrier status and potential risk.