Serum and Urinary sCD163 in IgA Nephropathy

This is a single-center observational study involving patients with biopsy-proven IgA nephropathy. The study includes both retrospectively collected clinical and histopathologic data and prospectively collected follow-up data, in accordance with the approved study protocol. Serum and urinary soluble CD163 levels will be measured and evaluated in relation to demographic characteristics, kidney function, proteinuria, hematuria, and other relevant laboratory parameters.

Histopathologic severity will be assessed using kidney biopsy findings, including Oxford MEST-C classification components where available. Associations between soluble CD163 levels and markers of disease activity, histopathologic lesions, and renal outcomes will be examined. Follow-up assessments will include changes in estimated glomerular filtration rate, serum creatinine, and proteinuria, as well as other predefined renal outcomes.

No study-specific therapeutic intervention will be assigned. All treatment decisions will be made by the treating physicians according to routine clinical practice. The study is designed to investigate the potential value of serum and urinary soluble CD163 as biomarkers of disease activity, histopathologic severity, and prognosis in IgA nephropathy.

Inclusion criteria

• - Age 18 years or older
• Biopsy-proven primary IgA nephropathy or primary focal segmental glomerulosclerosis
• Stable kidney function with an estimated glomerular filtration rate greater than 30 mL/min/1.73 m²
• Availability of serum and urine samples for soluble CD163 measurement
• Availability of relevant demographic, clinical, laboratory, histopathologic, and follow-up data
• For the healthy control group: age- and sex-matched individuals without known chronic disease and with normal kidney function
• Written informed consent

Exclusion criteria

• - Secondary IgA nephropathy or secondary focal segmental glomerulosclerosis
• Active infection
• Acute kidney injury
• End-stage kidney disease or ongoing dialysis treatment
• Estimated glomerular filtration rate below 15 mL/min/1.73 m²
• Recent use of corticosteroids or immunosuppressive therapy
• Pregnancy
• Active malignancy or history of malignancy
• Inadequately stored or unavailable serum and/or urine samples
• Missing essential clinical, laboratory, histopathologic, or follow-up data
• Absence of written informed consent