Exploring urinary allantoin and adenosine in pediatric autosomal dominant polycystic kidney disease: no clear association with disease severity

Proteinuria and hypertension are commonly observed in children with autosomal dominant polycystic kidney disease (ADPKD), but reliable non-invasive biochemical markers for early disease activity or progression in pediatric ADPKD are lacking. Allantoin and the allantoin/uric acid ratio are recognized oxidative stress biomarkers in chronic kidney disease and may hold potential for early disease monitoring in ADPKD.

In this observational study, 34 patients with genotyped PKD1-ADPKD under 18 years with preserved kidney function were compared to 31 healthy controls. Urinary allantoin and adenosine were measured using a validated high-performance liquid chromatography (HPLC)-UV method. Associations with established markers of disease progression, including estimated glomerular filtration rate, total kidney volume (TKV), and the Leuven Imaging Classification (LIC) score, were assessed.

Urinary allantoin, adenosine and the urinary allantoin/uric acid ratio did not differ significantly between patients and controls. In the ADPKD cohort, significant negative correlations were found between urinary allantoin and TKV (r = −0.49 P = 0.0043) and between urinary allantoin/uric acid ratio and TKV (r = −0.41 P = 0.0228). No correlations were observed between urinary allantoin and LIC score. Across all participants, urinary allantoin levels negatively correlated with age (r = −0.54 P = 0.0015; r = −0.74 P = 8.75e−007).

Although urinary allantoin, adenosine, and the allantoin/uric acid ratio were comparable between pediatric patients with ADPKD and controls, inverse associations between allantoin and TKV were observed between the groups. However, the lack of correlation with LIC score and the negative correlation with age limit its potential as a marker in pediatric ADPKD.