Acute kidney injury (AKI) may be an independent risk factor for kidney stones with risk increasing along with AKI severity, according to investigators.
In an Australian local health district attending 137,635 patients from 2008 to 2017, 23,001 patients (17%) received an AKI diagnosis, including 71% in a hospital setting and 29% in an outpatient setting. Over the 10-year period, 2295 patients (2%) presented with kidney stones, including 262 with previous AKI. The median time to kidney stone development after an AKI episode was 2.2 years.
In multivariate analysis and a propensity-score matched analysis, AKI was significantly associated with 45% and 67% increased risks for future kidney stones, respectively, compared with no AKI, Hicham I. Cheikh Hassan, MBBS, of Illawarra and Shoalhaven Local Health District in Wollongong, New South Wales, Australia, and colleagues reported in Nephrology Dialysis Transplantation. Stone risk was significantly increased after both inpatient and outpatient AKI. AKI stage 1, 2, and 3 was significantly associated with a 2.3-, 2.6-, and 2.7-fold increased risk for kidney stones, respectively. Propensity score matching accounted for age, gender, chronic kidney disease, hypertension, diabetes, coronary artery disease, congestive heart failure, arrhythmia, and cancer. The database lacked information on other relevant factors, such as patients’ body mass index, urine composition, medications, and fluid intake.
AKI is associated with renal tubular damage and scarring that may impair the normal urinary-concentrating and ion-regulating mechanism of the nephron, the investigators explained. AKI may also disrupt normal mineral balance and metabolite excretion. Some research suggests AKI reduces expression of kidney stone inhibitors such as uromodulin and urinary citrate. Finally, AKI management may unwittingly foster kidney stone formation.
“Our study contributes novel information adding to the list of adverse sequelae after an episode of AKI, where much of the literature has focused on the risk of chronic kidney disease, end-stage kidney disease and death,” Dr Hassan’s team wrote.
Hassan HIC, Murali K, Lambert K, et al. Acute kidney injury increases risk of kidney stones—a retrospective propensity score matched cohort study. Nephrol Dial Transplant. Published online February 2, 2022. doi:10.1093/ndt/gfac023