Abstract: PO1466
Curious Case of Bartter Syndrome-Like Phenotype Unmasked by Diuretics
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Clinical - 1
October 22, 2020 | Location: On-Demand
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Report
- 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- Gopinath, Prathima, Marshfield Clinic Health System, Marshfield, Wisconsin, United States
- Ravipati, Krishna S., Marshfield Clinic Health System, Marshfield, Wisconsin, United States
- Chanumolu, Pramodh, Marshfield Clinic Health System, Marshfield, Wisconsin, United States
- Kattamanchi, Siddhartha, Marshfield Clinic Health System, Marshfield, Wisconsin, United States
Introduction
SLC12 A1 mutations have been associated with Bartter syndrome type 1. Here we present a case of severe hypokalemia with diuretics which when investigated led to discovery of a novel SLC12A1 mutation which might have predisposed the patient to Bartter syndrome like phenotype.
Case Description
68 y/o f with no history of hypokalemia developed heart failure with preserved ejection fraction and was started on low dose loope diuretics which was gradually increased to1-1.5 mg po daily Bumetanide. She developed severe hypokalemia with diuretics which worsened with increasing diuretic doses, needing enormous amounts of potassium supplements. She continued to have persistent hypokalemia (serum potassium 3.0- 3.5 mmol/L) with significant urinary potassium excretion despite being on 260 mEq of oral potassium supplement/day, which improved mildly with addition of Amiloride. She also was hypotensive and was alkalotic secondary to diuresis. Given the significant kaliuresis leading to severe hypokalemia which was out of proportion to the dose of diuretics we did Genetic testing for presence of Bartter’s mutation. Genetic testing revealed a novel heterozygous variant mutation in SLC12A1 gene. It showed 1972 C>T transition in exon 16 of SLC12A1 gene. This change converts a codon for leucine (CTT) to a codon for phenylalanine (TTT).
Discussion
Bartter syndrome (BS) type 1 is an autosomal recessive disorder caused by loss of function mutations. Mutations in SLC12A1 gene leading to dysfunction of NKCC2 co-transporter is one of the known mutations associated with Bartter’s syndrome. There have been cases of heterozygous mutations of SLC12A1 gene which presented as Bartter syndrome. Our patient is unique as she has a novel heterozygous variant mutation in SLC12A1 gene and this mutation has not been reported to be associated with bartter syndrome. We believe this mutation might cause mild bartter phenotype. Our patient probably has a mild sublicnical Bartter like phenotype secondary to heterozygous variant of the mutation and developed severe hypokalemia when exposed to loop diuretics. Pursuing genetic testing for inappropriately severe hypokalemia needing exorbitant amount of potassium supplementation in a patient due to loop diuretic is a worthy consideration. Further research into this variant is needed to confirm it's pathogenicity.