Abstract: TH-PO1121

Proximal Tubular Function in Patients with Multiple Sclerosis

Session Information

Category: Fluid, Electrolytes, and Acid-Base

  • 704 Fluid, Electrolyte, Acid-Base Disorders

Authors

  • Allegretti, Andrew S., Massachusetts General Hospital, Boston, Massachusetts, United States
  • Payas, Nydjie, Biogen, Cambridge, Massachusetts, United States
  • Krinsky, Scott, Mass General Hospital, Boston, Massachusetts, United States
  • Thadhani, Ravi I., Massachusetts General Hospital, Boston, Massachusetts, United States
  • Bhan, Ishir, Biogen, Inc, Cambridge, Massachusetts, United States
Background

A recent database study revealed evidence of a higher than expected prevalence of Fanconi syndrome diagnosed in patients with multiple sclerosis (MS) relative to the general population. Proximal tubular function, which is altered in Fanconi syndrome, has not been evaluated in patients with MS. Our objective was to compare the patterns of urinary electrolyte and amino acid excretion between MS and age- and gender-matched non-MS controls.

Methods

Subjects aged 18 or older with a diagnosis of MS were eligible to participate as cases; controls were age- and gender-matched individuals without MS. Exclusion criteria included known chronic kidney disease or kidney transplantation, use of a drug known to inhibit renal carbonic anhydrase, or use of a drug known to cause Fanconi syndrome. A blood sample was collected for a basic metabolic panel plus phosphorus. Urinalysis was performed and urine was assayed for electrolytes, glucose, creatinine and a panel of 28 amino acids. Univariate analysis was performed using Chi square and Wilcoxon testing.

Results

11 MS patients (10 females, 1 male) participated, age and gender matched to 20 non-MS controls (17 females, 3 males). 10/11 MS patients were on disease-modifying therapy, including dimethyl fumarate (4/11), glatiramer (2/11), fingolimod (2/11), interferon (1/11), and natalizumab (1/11). Median age among MS patients and controls was 45 [IQR 32, 59] and 53 [IQR 31, 63] years, respectively. Race, ethnicity and gender were similar between groups. Mean levels of 17 /28 (61%) urinary amino acids were higher in MS patients than controls (p <0.05 for carnosine, glutamate, hydroxyproline, and proline). Urinary amino acids were generally in the normal range, but abnormal levels were more common in MS patients for 8 amino acids and normal in all individuals for the remainder. Increased urinary amino acids were not associated with a particular MS treatment. MS patients had greater urine sodium levels (97 [IQR 73, 125] vs. 55 [IQR 29, 75] mmol/L; p = 0.03) and similar levels of urine potassium, chloride and phosphorus.

Conclusion

MS patients with normal kidney function may be at higher risk of urinary amino acid wasting. Future studies are needed to verify these findings and to elucidate whether MS or its treatment predispose to previously unrecognized proximal tubular dysfunction.

Funding

  • Commercial Support