# Consequences of Nephrotic Proteinuria and Nephrotic Syndrome after Kidney Transplant

## TL;DR

Nephrotic proteinuria and syndrome after kidney transplants are common and strongly linked to poor outcomes, with early development of syndrome indicating worse survival.

## Contribution

The study provides new insights into the clinical and histopathological features of nephrotic-range proteinuria and its association with graft survival after kidney transplantation.

## Key findings

- Nephrotic-range proteinuria occurred in 18.6% of kidney transplants.
- Graft survival dropped from 75.8% at 12 months to 38% at 5 years after NP onset.
- Early development of nephrotic syndrome was linked to higher graft loss risk.

## Abstract

Proteinuria is the main predictor of kidney graft loss. However, there is little information regarding the consequences of nephrotic proteinuria (NP) and nephrotic syndrome (NS) after a kidney transplant. We aimed to describe the clinical and histopathological characteristics of kidney recipients with nephrotic-range proteinuria and compare the graft surveillance between those who developed NS and those who did not. A total of 204 patients (18.6% of kidney transplants in the study period) developed NP, and 68.1% of them had NS. Of the 110 patients who underwent a graft biopsy, 47.3% exhibited ABMR, 21.8% the recurrence of glomerulonephritis, 9.1% IFTA, and 7.3% de novo glomerulonephritis. After a median follow-up of 97.5 months, 64.1% experienced graft loss. The graft survival after the onset of NP declined from 75.8% at 12 months to 38% at 5 years, without significant differences between those with and those without NS. Patients who developed NS fewer than 3 months after the onset of NP exhibited a significantly higher risk of death-censored graft loss (HR: 1.711, 95% CI: 1.147–2.553) than those without NS or those with late NS. In conclusion, NP and NS are frequent conditions after a kidney transplant, and they imply extremely poor graft outcomes. The time from the onset of NP to the development of NS is related to graft survival.