Category: Clinical Stones: Medical Management
Introduction & Objective :
Both European Association of Urology (EAU) and American Urological Association (AUA) Guidelines recommend that a stone analysis (SA) be performed to direct additional workup for calcium oxalate stone formers. Previous studies have suggested calcium oxalate dihydrate (COD) stones associated with hypercalciuria and calcium oxalate monohydrate (COM) stones with hyperoxaluria, mostly in a retrospective fashion. We aimed to test this association in a prospective cohort study.
From November 2015 to March 2018, patients prospectively enrolled in the Registry for Stones of the Kidney and Ureter (ReSKU) who had both a SA and 24-hour urinalysis comprised this study cohort. For each patient, the 24-hour urine performed closest to the date of the stone analysis was utilized, with standard definitions of hypercalciuria and hyperoxaluria applied. Stone types were determined by infrared spectroscopy and considered primarily COM and COD if these compositions comprised >50% of the stone. Two-sample proportion tests were performed for statistical analysis, with statistical significance considered p
A total of 113 patients met inclusion criteria, with a mean interval of 105 +75 days between SA and 24-hour urinalysis. The SA among these patients showed 22 (19%) COD, 59 (52%) COM, 16 (14%) calcium phosphate (carbonate or brushite), and 16 (14%) other (uric acid, cystine, struvite, matrix). Hyperoxaluria was present in 25/59 (42%) of COM patients, representing a significantly higher proportion compared to non-COM patients (p=0.03). While hypercalciuria was present in 12/22 (55%) of patients with COD, this percentage approached but did not achieve statistical significance in comparison to non-COD patients (p=0.06).
Among calcium oxalate forming stone patients, a significantly higher proportion of COM patients compared to non-COM patients demonstrate hyperoxaluria. While the determination of stone composition remains an important part of the workup for future stone management, the association between both COD & hypercalciuria as well as COM & hyperoxaluria deserve further study. If established, these relationships may help direct medical management independent of 24-hour urine collections.
David Tzou– Assistant Professor, University of Arizona, Tucson, Arizona
Manuel Armaz Villaneda– San Francisco, California
Scott Wiener– Clinical Fellow, UCSF, San Francisco, California
David Bayne– Clinical Fellow, UCSF, San Francisco, California
Shalonda Reliford-Titus– UCSF Department of Urology, San Francisco, California
Marshall Stoller– Professor, UCSF, San Francisco, California
Thomas Chi– Associate Professor, UCSF, San Fransisco, California
San Francisco, California
Scott Wiener is a clincal fellow in endourology at UCSF.
San Francisco, California
David Bayne, MD, MPH
UCSF Urology Endo/Lap Fellow
BA in Biochemistry at Harvard College 2006
MD at Harvard Medical School 2012
MPH at UC Berkeley in 2017
Residency in Urology at UCSF 2018
San Fransisco, California
Thomas Chi, MD
Associate Chair for Clinical Affairs
Kutzmann Endowed Professor for Clinical Urology
UCSF Department of Urology
Dr. Thomas Chi, MD, graduated as a President's Scholar from Stanford University with a BA in Human Biology and MAs in Sociology and Music. He earned his MD from the University of California, San Francisco where he also completed urology residency and a fellowship in Endourology and Laparoscopy under the mentorship of Dr. Marshall L. Stoller.
During his fellowship, Dr. Chi was awarded grant funding from the National Institutes of Health and the American Urological Association Urology Care Foundation to research the fundamental mechanisms underlying the formation of urinary stones.
He joined the UCSF faculty of the Department of Urology in 2013 where his clinical interests include the care of patients with urinary stone disease and those in need of minimally invasive surgery. He specializes in the performance of endoscopic, laparoscopic, and percutaneous surgeries as well as HoLEP. He has established ReSKU, the Registry for Stones of the Kidneys and Ureter, the first kidney stone registry of its kind for tracking patient clinical outcomes and is an internationally recognized specialist in the use of ultrasound in the management of kidney stones to minimize patient radiation exposure.
In addition to his clinical interests, Dr. Chi supervises an NIH-funded translational science lab where he leads a cross-disciplinary research team. His research focuses on understanding the genetic and microbial environment of the kidney related to how kidney stones form and developing new medical preventative interventions. He has developed a novel model fruit fly for the study of kidney stones and has published over 80 peer-reviewed articles and book chapters spanning both basic science as well as epidemiologic approaches centered around improving the care of patients with urinary stone disease.