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Unilateral hypercalciuria: a stealth culprit in recurrent ipsilateral urolithiasis in children
Gregory E Tasian1, Justin Ziemba, Pasquale Casale
1Division of Urology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
Insights
Unilateral hypercalciuria, an isolated increase in urine calcium, can occur in children with recurrent kidney stones in one kidney. This finding suggests it
Area of Science:
- Pediatric Nephrology
- Urology
- Metabolic Disorders
Background:
- Hypercalciuria is a known risk factor for nephrolithiasis (kidney stones).
- Previous studies focused on generalized hypercalciuria, not kidney-specific variations.
Purpose of the Study:
- To investigate the hypothesis that children with recurrent kidney stones in one kidney, but not both, may exhibit isolated hypercalciuria in the affected kidney.
- To determine if unilateral hypercalciuria is a distinct risk factor in pediatric nephrolithiasis.
Main Methods:
- A study included 329 pediatric patients (≤18 years) with symptomatic urolithiasis who underwent ureteroscopic stone removal.
- Urine samples were collected from both the bladder and the renal pelvis of the affected kidney.
- Spot urine calcium-to-creatinine ratio was analyzed, excluding patients with elevated 24-hour bladder urine ratios.
Main Results:
- Nine out of 74 subjects (12%) with recurrent stones in one kidney showed an increased urine calcium-to-creatinine ratio from the affected kidney.
- No elevated ratios were found in other patient cohorts (single stone in one or both kidneys, recurrent stones in both kidneys).
- Patients with recurrent unilateral stones had significantly higher affected kidney urine calcium-to-creatinine ratios compared to other stone formers (p <0.001).
Conclusions:
- Unilateral hypercalciuria can be present in children even with normal overall bladder urine calcium levels.
- This localized kidney hypercalciuria should be considered a potential risk factor for nephrolithiasis in children experiencing recurrent stones in a single kidney.
Purpose:
Hypercalciuria is a risk factor for nephrolithiasis. We hypothesized that children with recurrent stones in 1 but not both kidneys and a normal 24-hour bladder urine calcium-to-creatinine ratio might exhibit isolated hypercalciuria of the affected kidney.
Materials And Methods:
Patients 18 years or younger with symptomatic urolithiasis who had undergone ureteroscopic stone removal were included. All subjects underwent 24-hour bladder urinalysis. Subjects with an increased urine calcium-to-creatinine ratio from the 24-hour urine collection were excluded. The 4 subject cohorts defined were 1) single stone episode in 1 kidney, 2) single stone episode in both kidneys, 3) recurrent stone episodes on 1 side and 4) recurrent stone episodes on both sides. All urine collections were obtained at ureteroscopy. Urine was obtained from the bladder and from the renal pelvis of the kidney forming the stone. Spot urine calcium-to-creatinine ratio was determined from these samples.
Results:
A total of 329 patients were included. Nine of 74 subjects (12%) with recurrent stone episodes on 1 side had increased spot urine calcium-to-creatinine ratio from the affected kidney. No patients in the other cohorts had increased spot urine calcium-to-creatinine ratio. Patients who formed recurrent stones in 1 kidney had increased spot urine calcium-to-creatinine ratio in the affected kidney vs other stone formers (ANOVA p <0.001).
Conclusions:
Unilateral hypercalciuria can occur in children with normal calcium levels in bladder urine. Unilateral hypercalciuria should be considered as a risk factor for nephrolithiasis in children with recurrent stone episodes in 1 kidney only.
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