# Predicting the Course of Immunoglobulin A Nephropathy Using Urinary Soluble Cluster of Differentiation 163 as a Prognostic Biomarker

## TL;DR

This study explores urinary soluble CD163 as a non-invasive biomarker to predict treatment response and disease activity in IgA nephropathy patients.

## Contribution

The study introduces urinary sCD163 as a novel prognostic biomarker for IgAN treatment outcomes and histologic activity.

## Key findings

- Baseline u-sCD163 levels significantly differ between partial and no-response groups.
- u-sCD163 levels at six months are highest in patients with no treatment response.
- Elevated u-sCD163 correlates with histologic features like endocapillary hypercellularity.

## Abstract

Background: Immunoglobulin A nephropathy (IgAN) is the most prevalent primary glomerulonephritis (GN) worldwide and is often underdiagnosed because of its asymptomatic presentation. Proteinuria-based assessment in monitoring disease progression is limited. Early renal biopsy may fail to predict disease severity. So, the development of a non-invasive biomarker can predict early disease progression.

Objective: To evaluate urinary soluble cluster differentiation 163 (u-sCD163) in predicting short-term treatment response and its correlation with histologic activity in biopsy-proven IgAN.

Methodology: This prospective observational study was carried out at the Department of Nephrology, Bangladesh Medical University (BMU), Dhaka, Bangladesh. A total of 55 patients with biopsy-proven primary IgAN were enrolled. Urine routine microscopic examination (R/M/E), 24-hour urinary total protein (UTP), and serum creatinine were measured at baseline, and at each follow-up (every three-month interval, up to six months). u-sCD163 was measured at baseline and at the sixth month. Patients were managed according to the KDIGO, 2021guideline and followed up in the third and sixthmonths.

Results: Mean age of the study patients was 31.3 ± 5.61 years. The sex distribution highlights a male predominance, as the male-to-female ratio was 1.7:1. Baseline u-sCD163 was 3.78 ± 0.96 ng/mg in the partial response group and 7.82 ± 4.00 ng/mg in the no-response group (P < 0.001). The receiver operating characteristic (ROC) curve analysis of urinary sCD163 level for predicting no response at the third month showed an optimal cutoff value of 4.80, providing a sensitivity of 76.7% and specificity of 83.3%. At six months, urinary sCD163 levels were highest in the no-response group (7.22 ± 3.41 ng/mg, P < 0.001). u-sCD163 was markedly elevated in patients with endocapillary hypercellularity and crescents (P < 0.05).

Conclusions: u-sCD163 may be a potential biomarker to predict the short-term treatment response status and histologic activity in biopsy-proven IgAN. Elevated biomarkers at baseline were associated with more proteinuria and risk of response failure.