Non-infectious Causes of Recurrent Flank Pain in Older Children

Objective: To find out the etiology of non-infectious recurrent flank pain in older children.Methods: The medical records of 84 consecutive children older than 5 years of age with non-infectious flank pain were retrospectively reviewed. Data checked included history, physical examination, laboratory investigations (serum creatinine, uric acid, and calcium), 24 hour urine collection for creatinine, calcium, oxalate, and uric acid, in addition to imaging studies. Those with systemic disease and urinary tract infection(UTI) were excluded. Results: The most common causes of recurrent non-infectious flank pain in older children were crystalluria (59.5%) and urolithiasis (17.8%). Amongst the crystalluria, hyperoxaluria was the most frequent. Other etiologies included constipation (6.0%), sterile vesicoureteral reflux (6.0%), and pelviureteric junction obstruction(4.7%).Family history was positive for stones in 45% of urolithiasis cases.Renal ultrasonography was adequate for diagnosing all kidney stonesand unenhanced helicalcomputed axial tomography(UHCT)diagnosed ureteral stones with typical renal colic pain radiating tothe groin. Constipation was found to be an important, yet overlooked cause of extraurinary flank pain.Conclusion: The most important non-infectious causes of recurrent flank pain in older children were crystalluria, urolithiasis, constipation, pelviureteric junction obstruction, and sterile vesicoureteral reflux. A positive family history of stones played a key role in initiating workup for crystalluria and urolithiasis. Focused histories and physical examinations were important in those cases with constipation as a cause of reversible flank pain.