Higher Relative Urine Supersaturations Up Stone Risk

NEW ORLEANS—Kidney stone formation becomes more likely with higher calcium oxalate and calcium phosphate relatively supersaturation levels, according to data presented at the American Society of Nephrology’s Kidney Week 2017 meeting.

The finding is from a cross-sectional study using 24-hour urine collections from 2505 stone formers and 1267 controls from the Nurses’ Health Study I (NHS I), Nurses’ Health Study II (NHS II), and Health Professionals Follow-up Study (HPFS) cohorts. Among participants with a calcium oxalate relative supersaturation of 3.0 or greater, those in NHS I and II had a 5.8 and 6.4 times increased relative risk of stone formation, respectively, compared with participants who had a relative supersaturation less than 1.0, Megan Prochaska, MD, of Brigham and Women’s Hospital in Boston, and colleagues reported. In the HPFS cohort, those with a calcium oxalate relative supersaturation of 4.0 or higher had a nearly 7-fold greater relative risk of stone formation compared with individuals who had relative supersaturation less than 1.0.

Among individuals with a calcium phosphate relative supersaturation of 4.0 or higher, those in the NHS I, NHS II, and HPFS cohorts had nearly 1.9-, 4.4-, and 3.6-fold increased relative risk of stone formation compared with individuals who had relative supersaturation less than 1.0.

Among individuals with a uric acid relative supersaturation of 4.0 or higher, those in the NHS I and II cohorts had an approximately 4.3- and 2.7-fold increased relative risk of stone formation, respectively, compared with those who had a relative supersaturation less than 1.0. The study found no significant association between uric acid relative supersaturation and stone formation in the HPFS cohort.

Reference

Prochaska M, Taylor EN, Ferraro PM, et al. Relative supersaturation of 24-hour urine and likelihood of kidney stones. Data presented in poster format at Kidney Week 2017 in New Orleans (Oct. 31-Nov. 5). Abstract TH-PO1076.