BACKGROUND:Hyperkalemia is a frequent electrolyte alteration whose prevalence varies widely, depending on the adopted cutoff, the setting (inpatients versus outpatients), and the characteristics of the study population. Familial hyperkalemic hypertension (FHH) is a rare cause of hypertension, hyperkalemia, and hyperchloremic metabolic acidosis.METHODS:
In this retrospective observational study, we investigated the prevalence of hyperkalemia (serum K
+
>5.2 mmol/L on 2 repeated measurements) in 5100 referred patients affected by arterial hypertension, the potential causes, and the associated cardiovascular risk profile.
RESULTS:
Overall, 374 (7.3%) patients had hyperkalemia. This was associated with drugs known to increase K
+
levels (74.6%), chronic kidney disease (33.7%), or both (24.3%). Among the 60 patients with unexplained hyperkalemia, 3 displayed a clinical and biochemical phenotype suggestive of FHH that was genetically confirmed in 2 of them (0.04% in the entire cohort). FHH prevalence rose to 3.3% in patients with unexplained hyperkalemia and up to 29% (2/7) if they had serum K
+
>5.8 mmol/L. The genetic cause of FHH was a missense variant affecting the acidic motif of
WNK1
in 1 family and a rare
CUL3
splicing variant, whose functional significance was confirmed by a minigene assay, in another. Finally, we observed a significant association between hyperkalemia and the occurrence of cardiovascular events, metabolic syndrome, and organ damage, independent of potential confounding factors.
CONCLUSIONS:The identification of hyperkalemia in patients with hypertension has prognostic implications. A timely diagnosis of FHH is important for effective management of hypertension, electrolyte imbalance correction with tailored treatment, and genetic counseling.