Kidney biopsy in patients with small kidneys: diagnostic yield and treatment modification in a retrospective cohort study.

BACKGROUND

Reduced renal size has traditionally been considered a relative contraindication to kidney biopsy because of the perception that advanced chronic damage provides limited diagnostic or therapeutic benefit. However, the actual clinical value of renal biopsy in patients with small kidneys remains insufficiently investigated.

METHODS

We conducted a retrospective single-center study including patients with chronic kidney disease who underwent renal biopsy between June 2020 and December 2025. Patients with renal length ≤9 cm were defined as having small kidneys. Baseline clinical data, pathological diagnoses, treatment modifications following biopsy, and follow-up clinical outcomes were analyzed. Subgroup analyses were performed according to pathological categories.

RESULTS

Among 1,084 biopsied patients, 76 (7.0%) had small kidneys. Renal biopsy revealed heterogeneous etiologies, with IgA nephropathy (IgAN) accounting for 46.1% of cases. Treatment strategies were modified in 67.1% of patients after renal biopsy. During follow-up, biopsy-guided management was associated with reduced proteinuria and stable renal function.

CONCLUSIONS

In selected patients with small kidneys, renal biopsy was associated with high diagnostic yield and frequent treatment modifications.