How to diagnose and evaluate a child with urolithiasis:

How to diagnose and evaluate a child with urolithiasis:

Because of the possibility of an underlying metabolic disorder, children with urolithiasis should have a careful evaluation, including the following:

  1. Laboratory testing should include electrolytes, BUN, creatinine, calcium, phosphorus, parathyroid hormone (PTH) level, uric acid level, and venous blood gas to rule out RTA.

  2. Urine testing should include urinalysis with microscopy, urinary oxalate-to-creatinine ratio to identify hyperoxaluria, random first morning urine for calcium-to-creatinine ratio to identify hypercalciuria and uric acid-to-creatinine ratio to identify

hyperuricosuria, urine culture, and testing for cystinuria. Twenty-four–hour urine collections are important to measure 24-hour urinary excretion of creatinine, oxalate, uric acid, citrate (low urinary citrate predisposes to stone formation), calcium, phosphorus,

magnesium, and cysteine.

  1. Imaging studies, including a plain radiograph of the abdomen and renal ultrasound, are necessary to confirm and identify the stone(s). Sometimes a high-resolution abdominal

CT scan can identify the stone.

  1. Stone fragment analysis, if a fragment is collected.