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/d...

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..