Do you perform a repeat kidney biopsy in a patient with IgA nephropathy who has achieved partial proteinuria reduction on current therapy but has not reached the target of below 1 g per day, to assess residual histologic activity before escalating treatment?

I would not recommend a routine repeat biopsy to assess residual histologic activity before escalating therapy for a partial proteinuria response in IgA nephropathy (IgAN). Instead, I base treatment escalation entirely on clinical trajectory, specifically persistent proteinuria (>1 g/day or ≥0.5 g/day), estimated glomerular filtration rate (eGFR) slope, and prior biopsy results, as emphasized by Kidney Disease: Improving Global Outcomes (KDIGO) guidelines (Floege et al., PMID 40975525).

I do not rely on repeat biopsies for these decisions because tissue samples provide only a snapshot, and no prospective trials prove that guiding treatment by Oxford Classification MEST-C scores (mesangial hypercellularity, endocapillary hypercellularity, seg...

Treatment decisions in IgAN are traditionally made on proteinuria and, increasingly, hematuria. The original biopsy may have an influence if crescentic, but follow-up histology is not a validated marker for treatment decisions.

The easy answer on this question is no.

Once you have the diagnosis, not sure further histological data will help.

No repeat biopsy is indicated once the diagnosis has been established, except in kidney transplant with worsening proteinuria after an initial improvement, in whom a repeat kidney biopsy may be warranted..