Kidney function may have an important role in modulating risk factors for kidney stones and thus stone composition among patients with chronic kidney disease (CKD), investigators reported at the National Kidney Foundation’s 2022 Spring Clinical Meetings in Boston, Massachusetts.
As a result, strategies to ameliorate stone risk may need to vary with CKD stage, investigators Hari Nair, BA, of the Yale School of Medicine in New Haven, Connecticut, and colleagues concluded in a poster presentation.
Nair’s group analyzed 24-hour urine and blood chemistry findings from 929 kidney stone formers. Of these, 319 (34.3%) had CKD stage 1, 409 (44%) had CKD stage 2, and 201 (21.6%) had CKD stages 3-5.
As CKD progressed, the proportion of calcium stones declined and the proportion of uric acid stones increased, Nair and colleagues reported. The proportion of patients with calcium oxalate stones was 69.7% and 69.3% among those with CKD stages 1 and 2, respectively, declining to 53% among those with CKD stages 3-5. The proportions of patients with calcium phosphate stones decreased from 19.7% among patients with CKD stage 1 to 11.9% and 7.8% among those with CKD stages 2 and 3-5, respectively. The proportion of patients with uric acid stones rose from 9% of those with CKD stage 1 to 11.8% and 28.7% of those with CKD stages 2 and 3-5, respectively.
In addition, advanced CKD was associated with lower urine phosphorus, calcium, urinary pH, citrate, and ammonium. Urinary oxalate varied significantly by CKD stage, although the investigators observed no correlation trend.
Stone formers with advanced CKD were more likely to have an elevated supersaturation for uric acid, but decreased supersaturations for calcium salts, according to the investigators.
Nair H, Simmons K, Murphy E, et al. Kidney stone risk factors and stone type vary with CKD stage. Presented at the National Kidney Foundation’s 2022 Spring Clinical Meetings, Boston, Massachusetts, April 6-10, 2022. Poster 196.