Kidney pathology findings in pediatric patients with kidney injury and inflammatory bowel disease: a case series.

BACKGROUND

Patients with inflammatory bowel disease (IBD) are at risk of kidney pathologies such as IgA nephropathy (IgAN) and tubulointerstitial nephritis (TIN). Data on kidney abnormalities and treatments in pediatric IBD patients with kidney disease are limited. This study describes kidney pathology, treatments, and outcomes in pediatric IBD patients who underwent kidney biopsy at our center.

METHODS

We conducted a single-center retrospective case series at a quaternary pediatric hospital in Toronto, Canada. Pediatric IBD patients who underwent kidney biopsy between June 2018 and February 2024 were included. Clinical data were extracted via chart review; biopsies were reviewed by a kidney pathologist.

RESULTS

Twelve patients were included; 11 had Crohn's disease, and four were female. Biopsy findings included TIN (n = 4), focal segmental glomerulosclerosis (FSGS) (n = 1), IgAN (n = 1), and acute tubular necrosis (n = 1). Five biopsies (42%) showed normal or nonspecific findings. Biopsy indications included elevated creatinine (n = 10), nephrotic-range proteinuria (n = 1), and steroid-dependent nephrotic syndrome (SDNS) (n = 1). Kidney abnormalities appeared 8 years before IBD diagnosis in one case, within one year of IBD diagnosis in 3 cases, or 2-11 years post-IBD diagnosis in 7 cases. TIN treatments included prednisone, stopping suspected triggers (e.g., ustekinumab, vedolizumab), and/or escalating IBD therapy. All patients with TIN showed poor kidney function recovery. The patient with IgAN recovered completely after steroids. The patient with FSGS had remission of nephrotic syndrome after rituximab and treatment of IBD with infliximab.

CONCLUSIONS

TIN was the most common kidney finding but had a poor treatment response. Many biopsies were non-diagnostic. Early kidney surveillance in pediatric IBD may aid in the timely detection and management of kidney disease.