Presented by: Dor Rubinshtein MD
Urology department, Kaplan medical center

Introduction

Kidney stones are a common health problem with nearly 10% prevalence in the Western world. Studies of natural history of asymptomatic nephrolithiasis report that nearly 20% of kidney stones require surgical intervention within 3-4 years of their detection. Nevertheless, the clinical outcomes of untreated asymptomatic kidney stones remain uncertain, and evidence-based reports regarding their growth rate are scarce. This study aims to assess the growth rate of kidney stones based on multiple CT scans.

Materials

We retrospectively searched for all patients who were diagnosed with nephrolithiasis by non-contrast computed tomography (NCCT) from June 2020 to April 2023 and had a previous NCCT imaging, separated by at least 6 months, demonstrating the same renal stones. We reviewed the demographic, laboratory, and radiological data of all patients included in the cohort. Measurement of stone growth for the entire cohort was done initially, followed by comparing stone growth in patients with lower calyx stones to those with kidney stones in any other calyx. We referred to stone size by either the maximal length or by stone volume.

Results

,

Our cohort included 77 patients with 94 renal stones.  The average growth rate for all kidney stones in this cohort was 1.3 mm/yr for the maximal stone length and 81 mm³/yr by stone volume. Of the 94 renal stones, 40 were in the lower calyx (group 1), and the remaining 54 were in non-lower kidney calyces (group 2). There were no differences between the groups comparing the following parameters: average patient age (52 yr in group 1 and 51 yr in group 2), gender (87% males and 13% females vs. 89% males and 11% females, respectively), diabetes mellitus (20% and 10%), serum calcium (9.2±0.55 and 9.2±0.53), and urine pH (5.8±0.8, 6.1±0.7). The median stone size and volume for group 1 were 7.3 mm and 114 mm³, respectively, and 5.7 mm and 74.7 mm³ for group 2 (P=0.04). Group 1 displayed higher Hounsfield unit attenuation of 885±310 compared with 718±262 in group 2 (P=0.05). The mean growth rate in group 1 was 1.43 mm/yr, while in group 2, the growth rate was 1.1 mm/yr (P=0.06).

Conclusion

In this cohort, an overall average growth rate of 1.3 mm/year for kidney stones was observed. Lower calyx stones were significantly larger and exhibited a faster growth rate than stones in other kidney calyces. This observation holds potential clinical significance in terms of surveillance protocols and patient counseling. 

Funding

none

Lead Authors

sharon Shreiber,
Kaplan medical center

Co-Authors

Dan Haberman, MD
Department of Cardiology, Kaplan Medical Center

Brian Berkowitz, D.Sc
Weizmann Institute of Science

Ishay Dror, Ph.D
Weizmann Institute of Science

Dan Leibovici, MD
Urology department, Kaplan medical center

Yaniv Shilo, MD
Urology department, Kaplan medical center