Use of a random urinary protein-to-creatinine ratio for the diagnosis of significant proteinuria during pregnancy

OBJECTIVE: The purpose of this study was to evaluate whether a random urina ry protein-to-creatinine ratio is a clinically useful predictor of signific ant proteinuria (300 mg/24 hour), STUDY DESIGN: The medical records of 138 women who completed both a random urinary protein-to-creatinine ratio and a 24-hour urine collection for the evaluation of preeclampsia were reviewed. Urine samples for the random prot ein-to-creatinine ratio were collected before the 24-hour urine collection. With the use of a protein level of at least 300 mg in the 24-hour urine sa mple as the gold standard, the sensitivity and specificity of the random pr otein-to-creatinine ratio for the diagnosis of significant proteinuria were determined with a range of cutoffs. RESULTS: Fifty percent of the study population had significant proteinuria. The data suggest that a cutoff below 0.14 ruled out significant proteinuri a. The best cutoff of greater than or equal to 0.19 yields a sensitivity of 90% and a specificity of 70%. All of the false-negative test results had 2 4-hour urine protein levels below 400 mg; 13 of the 21 false-positive resul ts had levels that ranged from 250 to 300 mg. CONCLUSION: The random urinary protein-to-creatinine ratio is strongly asso ciated with the 24-hour total protein excretion. A level below 0.14 can rul e out significant proteinuria. A best cutoff of greater than or equal to 0. 19 is a good predictor of significant proteinuria. With further study, the random urinary protein-to-creatinine ratio could replace the 24-hour urine collection as a simpler, faster, more useful method for the diagnosis of si gnificant proteinuria.