Distinct metabolic characteristics and risk of stone recurrence in patients with multiple stones at the first-time presentation.
OBJECTIVE
To characterize the clinical and metabolic abnormalities of patients presenting with multiple stones and determine their risk of new stone formation.


METHODS
This retrospective case-controlled study consisted of 911 patients who had ureter stones for the first time and 107 age- and sex-matched patients without stones. The patients were classified into 2 groups: those with a single ureter stone (n = 690) and those with 1 or more additional stones somewhere in the ureter or kidney (n = 221). All patients underwent 24-hour urinary metabolic evaluation. The 240 patients (26.3%) who were followed for >12 months (median follow-up, 35.0 months) were included in recurrence analyses. Stone recurrence was defined as "new stone formation," namely, the radiographic appearance of stones that had not been present in previous examinations.


RESULTS
The multiple-stone group had significantly lower urinary citrate excretion than the single-stone (P = .011) and control (P = .003) groups. Compared with the single-stone group, it also had a higher incidence of hypocitraturia (P = .011) and stone recurrence (27 of 84 [32.1%] vs 29 of 156 [18.6%] patients; P = .025). Multivariate Cox regression analyses revealed that stone multiplicity (hazard ratio, 2.343; 95% confidence interval, 1.302-4.220; P = .005) was an independent predictor of recurrent stone formation. Kaplan-Meier curves showed identical results.


CONCLUSIONS
The patients with multiple stones had distinct metabolic characteristics, particularly hypocitraturia and a significantly higher risk of recurrence than patients with 1 stone. Patients with multiple stones, even if it is their first stone episode, should undergo metabolic evaluation and possibly also potassium citrate therapy to prevent future stones.
Department of Urology, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
Ho Won
HW
Kang
Department of Urology, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
Sung Pil
SP
Seo
Department of Urology, Wonkwang University Sanbon Hospital, Gunpo, Republic of Korea.
Whi-An
WA
Kwon
Department of Urology, College of Medicine, Eulji University, Daejeon, Republic of Korea.
Seung Hyo
SH
Woo
Department of Urology, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
Won Tae
WT
Kim
Department of Urology, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
Yong-June
YJ
Kim
Department of Urology, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
Seok-Joong
SJ
Yun
Department of Urology, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea. Electronic address: lscuro@chungbuk.ac.kr.
Sang-Cheol
SC
Lee
Department of Urology, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
Wun-Jae
WJ
Kim
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D055815:Young Adult