KIDNEY RE-BIOPSY IN ADULTS WITH IGA NEPHROPATHY

IgA Nephropathy (IgAN) is the commonest worldwide primary

glomerulonephritis in adults. Despite a relevant role of kidney re-biopsy in renal

transplantation and lupus nephritis, its usefulness in IgAN has not been well ascertained. We

analyze those IgAN cases that have been re-biopsied and evaluate the potential impact in

clinical and histological outcomes.

Retrospective, observational study between years 1996 and 2021. Variables

included: Age, gender, Oxford score, glomerular filtration rate (GFR), 24-hour proteinuria

and cause of second biopsy. The impact on therapeutic interventions after re-biopsy was

analyzed.

IgAN prevalence: 15.8% (n=133) over 839 biopsies performed due to

glomerulopathies. 23 patients underwent a kidney re-biopsy 7.8±3.95 years after the first one.

Initial characteristics of these 23 patients at the time of diagnosis: Mean age 32±11.55 years,

of which 65% (n=15) were males; mean GFR 74.3±2.03 mL/min; 61% (n=14) of patients had

proteinuria 2.12±0.65 g/day, while 26% (n=6) presented with <1 g/day: 0.4±0.33, and 13%

(n=3) had nephrotic range proteinuria: 8.7±1.87g/day. Oxford score: M1 100%, E1 17%, S1

65%, T1 17%, C1 17%. All patients received nephroprotection and RASi as tolerated at the

time of diagnosis, while 13% (n=3) required the addition of corticosteroids (GFR: 34.6±9.28

mL/min; proteinuria 4.72±4.31 g/day; Oxford: M1 100%, E1 33%, S1 33%, T1 33%, C1 0%)

and 9% (n=2) the addition of corticosteroids plus mycophenolate (GFR mean 113.5±0.5

mL/min; proteinuria 1.95±0.65 g/day; Oxford: M1 100%, E1 100%, S1 100%, T1 100%, C1

0%).

Causes of re-biopsy: persistence of proteinuria despite therapy: 1.43±0.92 g/day (n=19;

82.6%) or a decrease in GFR: 47.32±24.79 mL/min (n=4.17.4%). Re-biopsy findings:

Oxford score M1 96% n=22; E1 13% n=3, S1 47% n=11, T1 26% n=6, C1 0.22% n=1. After

re-biopsy, all patients continued with nephroprotection, corticosteroids were discontinued in

2 patients and mycophenolate in 1; in all others, the immunosuppression was continued due

to the histologic findings (E1, C1). Final GFR 57.3±24.89 mL/min; 3 patients progressed to

end-stage renal disease. GFR decreased 26.48 mL/min from first to re-biopsy during the

7.8±3.95 years of follow-up. Final proteinuria levels: 47.82% (n=11) patients, 1.74±0.41

g/day; 47,82% (n=11) with <1 g/day: 0.28±0.12, while 4.36% (n=1) presented nephrotic

range proteinuria 4.07 g/day.

Re-biopsies in IgAN may add information regarding active tissue inflammation

that may lead to maintenance immunosuppression, despite decreases in proteinuria. Non-

significant histologic changes were observed between first and second biopsies. IgAN

significantly decreased renal function during follow-up time. These findings could suggest

the persistence of histological activity with a consequent drop in GFR despite a significant

decrease in proteinuria. Large-scale prospective studies are mandatory to evaluate the

usefulness of kidney re-biopsy in IgAN.