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Kidney Week

Abstract: TH-PO725

Markers of Potassium Homeostasis and Quality of Life in Salt Losing Tubulopathies

Session Information

Category: Genetic Diseases of the Kidney

  • 1002 Genetic Diseases of the Kidney: Non-Cystic

Authors

  • Kikic, Zeljko, Medical University of Vienna, Vienna, Austria
  • Reindl-Schwaighofer, Roman, Medical University of Vienna, Vienna, Austria
  • Bojic, Marija, Medical University of Vienna, Vienna, Austria
  • Darmann, Elisabeth, Medical University of Vienna, Vienna, Austria
Background


Gitelman and Barter Syndrome are the most frequent genetically inherited salt losing tubulopathies (SLT) with limited treatment options and quality of life (QOL) is reduced. Treatment options include supplementation of potassium (K+) and magnesium, potassium sparing diuretics. However evidence from randomized controlled trials indicate low efficacy of current treatments in terms of increasing K+. Morover K+ may not reflect the magnitude of the concommittant secondary hyperaldosteronism in those patients . Optimal endpoints for treatment trials should include QOL however little is known of optimal clinical cut-offs of laboratory values and their relation in SLT. The trans-tubular potassium gradient (TTKG) has been shown to be an accurate surrogate for hyperaldosteronism and of excellent use in other entities related to hyperaldosteronism like liver cirrhosis.

Methods


In this prospective cross-sectional study we included 11 patients with SLT. We measured laboratory parameters (K+, Mg++, Ca++, TTKG, Aldosteron) and their relation with QOL assessed by the RAND SF-36. The primary hypothesis was that TTKG may reflect QOL more accurately than K+ and serve as an end-point in future treatment trials. Secondary endpoints were the presence of cardiac arrhythmia in 24h ECG and cardiac abnormalities via ultrasound (US).

Results


The cohort consisted of mainly females with a median age of 29 years. The median K+ was 3.3 mmol/l and median TTKG 9.5. While there was a positive correlation of K+ and TTKG, we did not observe a significant correlation of TTKG with serum aldosterone. Comparing QOL domains we observed that TTKG showed a trend for better physical functioning while K+ was significantly related to emotional wellbeing and trend for energy and general health. Aldosterone was significantly related to role limitations emotional and physical. Urinary potassium with a threshold >20 mmol/l was inversely related with energy/fatigue and general health and a trend for emotional wellbeing while TTKG <10 or K+>3 mmol/l were not related to QOL. No relevant abnormalities were observed in either 24h ECG or cardiac US.

Conclusion


TTKG is not a suitable marker for hyperaldosteronism in SLT and K+ and TTKG are not sufficient endpoints for treatment trials for SLT in relation to QOL. Future treatment trials in SLT should include QOL assessment as well urinary parameters.