Elevated Creatinine Clearance in Lupus Nephritis patients with Normal Creatinine

Area of Science:

• Nephrology
• Rheumatology
• Internal Medicine

Background:

• Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect multiple organs, including the kidneys.
• Lupus nephritis (LN) is a common and serious complication of SLE, associated with significant morbidity and mortality.
• Early detection of renal involvement in SLE is crucial for timely intervention and improved patient outcomes.

Purpose of the Study:

• To investigate the relationship between urinary protein levels and creatinine clearance (Ccr) in SLE patients with normal serum creatinine.
• To identify potential indicators of early renal dysfunction or hyperfunction in lupus nephritis.

Main Methods:

• A cross-sectional study of 177 SLE patients with normal serum creatinine was conducted.
• Data collected included serum creatinine, blood urea nitrogen, proteinuria (urine protein/creatinine ratio - UPCR), and estimated Ccr using the Cockcroft formula.
• Patients were categorized based on urinary protein levels and UPCR values.

Main Results:

• SLE patients with positive urinary protein (LN group) showed higher blood urea nitrogen and serum creatinine levels compared to those without urinary protein.
• A strong correlation was observed between UPCR and semi-quantitative urine protein measurements in LN patients.
• Patients with minimal proteinuria (urine protein ± or UPCR < 0.15 g/g) demonstrated significantly elevated Ccr, suggesting kidney hyperfunction.

Conclusions:

• Early renal function impairment may be present in lupus nephritis patients, even with normal serum creatinine.
• The kidneys of LN patients with minimal proteinuria appear to be in a state of hyperfunction.
• These findings highlight the importance of monitoring urinary protein levels for early detection of renal involvement in SLE.