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Considerations

• 50% will have a recurrence within 3-5 years of first episode
• Increased risk for CKD, decreased BMD, and heart disease
• Obtain CT imaging only if renal US is nondiagnostic and clinical suspicion is high
• US stone criteria: hyperechoic focus in kidney + twinkle artifact (multicolor signal on Doppler), up to 25% false positive rate (higher than adults)
• Neonatal nephrocalcinosis: seen in 7-41% preterm infants in NICU, most resolve spontaneously, only 15% will require further interventions

Urine stone workup findings

• 24hr urine indications: low utility in obtaining in first-time stone formers, recommend empiric diet counseling and only performing workups for patients with recurrent stone formation (Carnes 2021)
• Hypercalciuria: 4 mg/kg/day if > 2yo, Ca/Cr ratio > 0.21mg/mg
• Hyperoxaluria: primary may require liver/kidney transplant, secondary caused by increased gut absorption, Lumasiran (Oxlumo) can be started as early as 3mo for patients with primary hyperoxaluria
• Hypocitraturia: Cit/Cr ratio < 128mg/g in boys and < 300mg/g in girls
• Cystinuria: normal excretion < 60 mg/d/1.73m² BSA
• Hyperuricosuria: leads to epitaxy (uric acid acts as nidus)

Prevention

• Fluids: up to 1.5-2L/m² for cystinuria
• Sodium: limit to 2-3mEq/kg/d or 2.4g/d in teenagers/adults
• Calcium: maintain normal levels, low Ca may worsen stone risks
• Protein: do not exceed normal requirements
• Oxalate: majority (80%) does not come from diet, but can limit if proven hyperoxaluria
• Protective factors: citrate, potassium, magnesium

Medications

• Alpha blockers: can be given for acute stone episode if < 10mm, overall utility unknown
• Thiazides: hypercalciuria resistant to low sodium diet, 1-2mg/kg/d
• K citrate: low/normal citrate and CaOx stones, 2-4mEq/kg/d
• Thiola: prevent disulfide bridge formation
• Allopurinol: hyperuricemia + hyperuricosuria, 4-10mg/kg/d (max 300mg/d), treat uric acid stones with hydration and alkalinization
• Pyridoxine: primary hypoxaluria Type 1, 2-5mg/kg/d and titrate up

Surgical management

• Up to 60% will require surgery
• Success rates: 70-97% PCNL, 85-88% URS, 80-83% ESWL
• URS: ureteral stones or renal stones < 2cm
• ESWL: renal stones < 1.5cm, increased need for retreatment if longer infundibulum or infundibulopelvic angle > 45 degrees
• PCNL: renal stones > 2cm
• Similar risks to adult stone surgery, may have higher need for pre-stenting due to narrow ureters