Endocrine Abstracts

Background: Kidney stones have been linked to chronic kidney disease and a higher probability of adverse cardiovascular events. Precise mechanisms that lead to these complications have not yet been elucidated. Most cases of kidney stones are idiopathic, related to metabolic disturbances like hypercalciuria, which often have a genetic background. There have been few reports of kidney stones associated with primary hyperaldosteronism (HA); however, the prevalence of HA in patients with kidney stones has not been fully examined.

Methods: We conducted a retrospective single-center study that included 181 patients evaluated for recurring kidney stones in whom basic laboratory tests to identify HA (plasma renin activity – PRA, plasma aldosterone concentration – PAC, and aldosterone to renin ratio – ARR) had been performed. The aim of the study was to assess the prevalence of laboratory evidence of HA (LEHA) in kidney stone patients and to identify clinical and laboratory characteristics associated with LEHA in this group of patients.

Results: The prevalence of LEHA was high. High ARR was identified in 39.8% patients, while a concurrent high PAC was identified in 21.5% (> 0.41 nmol/l) and 13.8% (> 0.55 nmol/l) of all patients. Arterial hypertension (AH) was identified in only about a quarter of patients with LEHA and the prevalence of LEHA was similar in patients with or without AH. Patients with LEHA and AH, particularly when associated with high PAC (> 0.55 nmol/l), exhibited some characteristic features of primary HA like lower serum potassium and higher serum bicarbonate. Patients with LEHA and without AH did not exhibit these features; however, they had higher serum phosphate associated with a trend towards lower urine phosphate excretion, a feature not present in patients with LEHA and AH. Patients with LEHA and AH were also older and tended to have their first stone event at a later age, while patients with LEHA and without AH had more stone-related urological procedures. An extremely low PRA value (< 0.07 μg/l/h) was present in 8.3% patients and was associated with a faster rate of decline in kidney function on follow-up.

Conclusions: Our study shows that LEHA can be common in patients with recurring kidney stones. Few of these patients present with typical features of primary HA. There are some distinct features of patients with LEHA and without AH, that could represent a separate phenotype in this population. The biological relevance of these findings is yet to be determined.