Objective To explore the value of urine soluble CD163 in predicting crescent formation in IgA nephropathy.

Methods A retrospective study was conducted in patients with renal biopsy-proven primary IgA nephropathy who were admitted to Zhongshan Hospital, Fudan University from January 2018 to December 2019. Patients who had hepatitis, autoimmune diseases, or received immunosuppressive agents less than 3 months prior to the renal biopsy were excluded. According to the 2016 Oxford classification of IgA nephropathy, patients were divided into the crescents free group and the crescents formation group. The concentration of urine soluble CD163 adjusted by urine creatinine in urine before the biopsy, and its correlation with clinical and laboratory data were analyzed.

Results Totally, 358 patients were analyzed, including 218 cases (60.9%) in the crescents free group and 140 cases (39.1%) in the crescents formation group. The concentration of urine soluble CD163 was significantly higher in the crescents formation group(6.72±10.90) ng/mg vs (3.54±6.72) ng/mg, P < 0.001. Urine sCD163 concentration was positively correlated with 24-hour urine protein quantification (r=0.593, P < 0.001) and crescent ratio (r=0.274, P=0.001), and was negatively correlated with renal function (r=-0.241, P < 0.001). In the subgroup of patients with proteinuria < 1 g/24 h and eGFR ≥ 30 mL·min^-1·(1.73 m²)^-1 with crescent formation, the urine sCD163 concentration was significantly increased (P < 0.05). The area under the ROC of the urine sCD163 concentration for judging crescent formation was 0.715 which was higher than that of eGFR (0.569, P < 0.000 1).

Conclusions Urine sCD163 concentration maybe increased significantly in IgA nephropathy patients with crescent formation which is closely related to the proteinuria, eGFR, and crescent ration. It may have a better performance in predicting the crescent formation in IgA nephropathy than that of proteinuria and eGFR, especially in patients with mild clinical manifestation.