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Abstract: FR-OR45

Complications and Treatment of Hypercalciuria in Familial Hyperkalaemic Hypertension (FHHt)

Session Information

Category: Fluid‚ Electrolyte‚ and Acid-Base Disorders

  • 1002 Fluid‚ Electrolyte‚ and Acid-Base Disorders: Clinical


  • D'Ambrosio, Viola, University College London, London, London, United Kingdom
  • Siew, Keith, University College London, London, London, United Kingdom
  • Walsh, Stephen B., University College London, London, London, United Kingdom

Hypertension is frequently associated with hypercalciuria1,2 ,nephrolithiasis3 and low bone mineral density4. Familial Hyperkalaemic Hypertension (FHHt) causes hypercalciuria5, although complications of this are not reported.


We examined a cohort of 9 patients with genetically confirmed FHHt. Biochemical, radiological, and clinical data was obtained in patients before and after thiazide treatment. All patients gave informed consent. The study had ethics committee approval (REC 05/Q0508/6). Data were compared using paired t tests or Wilcoxon paired rank tests.


5 of the 9 patients were female (median age 41.7 years). The genetic diagnosis was confirmed in all patients, 5 patients had variants in KLHL3, 3 patients had variants of WNK4, and one had a variant of WNK1.
Pre-treatment potassium was high (median 5.6 IQR 5.2-6.2 mmol/L). Pre-treatment calcium was in the normal range (2.34 IQR 2.29-2.38 mmol/L). There was significant hypercalciuria with a raised urinary calcium/creatinine ratio (0.69 IQR 0.41-1.13). However, PTH (4 IQR 3.95-4.35 pmol/L), phosphate (1.15 IQR 1.25mmol/L) and alkaline phosphatase (57 IQR 45-84 mmol/L) were all in the normal range.
Thiazide treatment significantly reduced hypercalciuria (calcium/creatinine ratio 0.15 IQR 0.05-0.29 p=0.04) as well as the serum potassium (3.9 IQR 3.5-4.4 mmol/L p=0.0167).
Patients also developed complications of hypercalciuria. 3 patients had kidney stones demonstrated on cross-sectional imaging. One of these patients (male, 30 years old) had DXA criteria for osteoporosis (T score Femoral neck -1.5, lumbar spine -2.4).


This is the first case series to demonstrate complications of hypercalciuria (i.e. kidney stones) in patients with FHHt. We demonstrate that thiazide treatment normalises urinary calcium excretion. Thiazide treatment may have clinical utility in FHHt even if hypertension or hyperkalaemia are not problematic in order to avoid the complications of hypercalciuria.