The protein–creatinine ratio in spot morning urine samples and 24-h urinary protein excretion in patients with systemic lupus erythematosus

A 24-h urinary protein is a standard way to diagnose lupus nephritis. Assessment of protein–creatinine (Pr–Cr) ratio in morning spot urine is a valuable method in diabetic patients but not use in systemic lupus erythematous (SLE) patients routinely. In this study Pr–Cr ratio in spot urine was compare with 24-h urine protein; if they have valuable correlation we can use this test instead of 24-h urinary protein. The aim of this study was to evaluate the correlation of spot urine Pr–Cr ratio for prediction of significant proteinuria (≥300 mg/24 h) in patients with SLE. A cross-section study was conducted in 74 hospitalized women with SLE. The correlation between Pr–Cr in first morning urine specimens and urinary protein excretion in 24-h collections were analyzed. Correlation between Pr–Cr ratio in spot morning urine specimens and urinary protein excretion in 24-h collections was significant (P < 0.0001, r = 0.83). A high correlation and precision of agreement were demonstrated between the two methods of assessment proteinuria in lupus patients. The difference between the two methods was less than the biological variability in the protein excretion and its measurement, enabling the methods to be used interchangeably creatinine ratio in spot morning urine samples is a precise indicator of proteinuria in patients with lupus nephritis and represents a simple and inexpensive procedure in establishing severity of proteinuria in patients with SLE.