Rare
But, children who form stones tend to be recurrent stone formers and need full investigation and workup.
Factors involved in paediatric stone formation
- Urinary concentration
- Dehydration, immobility
- Presence of abnormal metabolites or pathologically elevated levels of urine constituents
- Cystinuria
- Hyperoxaluria
- Half have primary hyperoxaluria
- Secondary hyperoxaluria after bowel resection, congenital enteropathies, cystic fibrosis
- Hypercalciuria
- In association with nephrocalcinosis, think RTA
- Xanthine oxidase deficiency -> xanthine stones
- Hyperuricosuria -> may be associated with chemotherapy
- Urinary infections
- Particularly urea splitting organisms
- Anatomical abnormalities
- Obstruction and stasis – PUJ obstruction, megaureter
- Neuropathic bladder
- Augmented bowel
- Reflux
- Foreign bodies
- Sutures, catheters, stents
- Prematurity
- Significant risk factor for stones
Presentation
Abdominal or flank pain.
Haematuria.
Investigation of UTI
Found on screening for neuropathic bladders, high risk patients with other conditions
Investigation
Urine culture and microscopy.
Bloods including renal function, serum calcium, U+Es, phosphate, bicarb, Mg, urate and PTH
Ultrasound most common and most useful.
XR historic but replaced now by ultrasound.
CT very sensitive/specific, but use limited due to radiation concerns
DMSA if appropriate.
Stone analysis very helpful
24 hour urine analysis when acute episode passed.
Metabolic workup
Metabolic factors contribute to 40 – 50 % of childhood stones.
24 hour urine analysis should be performed. Check creatinine levels as a weight based control value.
- Hypercalciuria most common metabolic abnormality detected
- Hypocitraturia, hyperuricosuria, hypomagnesuria, cystinuria may be detected.
- Hyperoxaluria -> consider liver biopsy for primary hyperoxaluria
Urine acidity – if alkaline urine – consider testing for RTA, renal physician referral.
Treatment and prevention
Treat the stone on its merits – conservative/MET, ESWL (ultrasound guided for children), ureteroscopy is now widely available, or PCNL.
MET looks to increase stone passage rates in meta-analysis of kids (doxasozin or tamsulosin 200 – 400 ug).
Open surgery when needed.
Prevention as per normal stones (all patients should have metabolic workup).