Hyperuricosuria and hypercalciuria, probable etiologies of functional abdominal pain: A case-control study

Functional abdominal pain (FAP) is a common complaint causing several referrals to pediatricians. On the other hand, the most common presentation of hyperuricosuria and also hypercalciuria is chronic/recurrent abdominal pain. Therefore, a hypothesis has been raised; abdominal pain due to hyperuricosuria and/or hypercalciuria may be misdiagnosed as FAP. The current study has aimed to respond to this theory.

This is a case-control study conducted on children diagnosed with FAP based on Rome IV criteria and age-matched normal controls. Blood and random urine samples were taken from healthy children and those with FAP. Random urine samples were examined for calcium, uric acid, oxalate, and creatinine concentrations. Random urine calcium to urine creatinine above 0.2 mg/mg was considered hypercalciuria and random urine uric acid above 0.56 mg/dl, GFR as hyperuricosuria. The data were analyzed using logistic models.

Hypercalciuric children had a significantly lower chance of FAP (odds ratio [OR] =0.425, 95% confidence interval [CI] =0.204-0.886). Although an inverse association was seen between hyperuricosuria and FAP (OR = 0.693, 95% CI = 0.395-1.214), it was not statistically significant. In stratified analyses by gender for both hyperuricosuria and hypercalciuria, a marginal inverse significant association was seen in male gender (P < 0.1).

Our study showed that hypercalciuria is significantly in inverse association with FAP but not hyperuricosuria. Therefore, these disorders, particularly hyperuricosuria may not be considered as the possible causes of FAP. Further studies with larger sample size for providing more reliable evidence are recommended.