Abstract: PUB508
Fanconi Syndrome and Hypomagnesemia: An Overlooked Association or Diagnostic Entity?
Session Information
Category: Trainee Case Report
- 902 Fluid and Electrolytes: Clinical
Authors
- Girgis, Christopher Hany, The University of Oklahoma - Tulsa, Tulsa, Oklahoma, United States
- Kathuria, Pranay, The University of Oklahoma College of Medicine, Tulsa, Oklahoma, United States
Introduction
Fanconi’s Syndrome is associated with hypophosphatemia, aminoaciduria, and renal glycosuria. However, there is significant variability in the phenotypical presentation of this disease process.
Time to diagnosis and length of underlying etiologies such as multiple myeloma or medications can play a role in the presentation, specifically between acquired and congenital Fanconi’s Syndrome.
Though typically not considered a classical association with Fanconi’s Syndrome, hypomagnesemia is occasionally noted in the literature in association with this disease and seems to be an underrecognized feature of this entity.
Case Description
A 65 year old female with history of recently diagnosed multiple myeloma (2 months prior), hypertension, and previously treated hypercalcemia now hypocalcemic presented with carpo-pedal spasms. One month prior she was treated with cyclophosphamide, bortezomib, dexamethasone, and denosumab.
Corrected calcium was 6.2 mg/dL, bicarbonate 16 mEq/L, potassium 2.4 mEq/L, chloride 112 mEq/L, magnesium 1.3 mEq/L, phosphorus 1.3 mg/dL, anion gap 15, and creatinine 1.42 mg/dL with AKI with a baseline of 0.6 mg/dL.
Urine bicarbonate was 8 in the setting of acidosis. Fractional excretion of magnesium was 28% in the setting of hypomagnesemia. Urine anion gap was 20, pH of the urine 8.0. No glucosuria. TTKG was 4.75 indicating potassium losses in the setting of hypokalemia. Aminoaciduria was present.
With these findinds, the diagnosis of Fanconi’s Syndrome, Renal Tubular Acidosis Type II in association with Multiple Myeloma was made. Oral replacements of electrolytes and Amiloride were started, with stabilization of electrolytes.
Discussion
Though hypomagnesemia is not classically noted as an association with Fanconi's Syndrome, such as glucosuria, aminoaciduria, and hypophosphatemia, it appears to be an under-recognized feature of this disease process. As stated in the limited literature with this association, there is cellular injury at the nephron primarily at the proximal tubular cells impairing passive reabsorption of magnesium in Fanconi’s Syndrome.
Underscoring this electrolyte disorder of this syndrome may better allow future clinicians to recognize hypomagnesemia in the setting of a non-anion gap metabolic acidosis and perhaps be considered as a diagnostic entity.