ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: PO1322

Insight into the Pathophysiology of Hearing Loss and Renal Tubular Dysfunction Through Genetic Testing

Session Information

Category: Genetic Diseases of the Kidneys

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • West, Dylan H., Baton Rouge General Medical Center - Bluebonnet, Baton Rouge, Louisiana, United States
  • Samuel, Jones, Baton Rouge General Medical Center - Bluebonnet, Baton Rouge, Louisiana, United States
Introduction

In this case report, we present a case of Type 3b Bartter’s Syndrome associated with sensorineural hearing loss.

Case Description

A 69 year old caucasian female with a history of hypertension and osteoporosis presented to the emergency department with a worsening dry cough, altered mental status, and paresthesias. Physical examination was positive for Chvostek's sign and hearing loss bilaterally. Laboratory analysis was significant hypolcalcemia, hypokalemia, and hypomagnesemia. EKG on presentation displayed significant QT prolongation (QTc of 482 ms). The patient was treated for symptomatic hypocalcemia and initiated on calcium, potassium, and magnesium supplementation. 24 hour urine collection yielded: potassium and magnesium wasting and normal range calciuria. Parathyroid hormone was found to be inappropriately low in the setting of severe hypocalcemia but attributed to hypomagnesemia. Bartter's vs. Gittleman's was suspected, although profound hypomagnesemia suggested the latter.

Renasight, a kidney gene panel employing next generation genome sequencing revealed a heterozygous variant in the basal chloride channel (CLCNKB), associated with Bartter’s Syndrome Type 3/4B. This channel is found in the stria vascularis and can lead to sensorineural deafness. Hypoparathyroidism persisted in spite of adequate Magnesium, Vit D levels suggestive of primary hypoparathyroidism of autoimmune etiology.

Discussion

The positivity of CLCKNB heterozygous mutation suggested Bartter's Type 3/4B and this explained hearing loss and aided in the final diagnosis.

Individuals who express both type A and B mutations present in infancy or antenatally. In a series of 115 patients w/ type B gene mutation, 26% had a Gitelman-like syndrome which includes late onset of age (1).

Our case illustrated the utility of genetic testing in mixed electrolyte wasting presentations. Interestingly, the patient has persistent hypoparathyroidsism for which no genetic basis was identified such as the calcium sensing receptor mutation.

Renal Studies
 MagnesiumPotassiumCalciumChlroideCreatininePTH
Urine 24 Hour130 mg/d72 MEQ/24hr346 mg/24hr95 MEQ/24hr835 mg/d 
Total Urine Volume2880 mL2880 mL2880mL2880 mL2880 mL 
Serum Concentration1.6 mg/dL4.5 mmol/L9.5 mg/dL95 mmol/L1.3 mg/dL27.5 pg/mL
Urine Fractional Excretion of Electrolyte18%34.87%    
Potassium/Creatinine Ratio 43 mg/gCr