NEW YORK (Reuters Health) – Rather than a 24-hour urine collection to measure proteinuria, a 12-hour urine protein determination and the protein:creatinine ratio can be used for evaluating suspected preeclampsia, according to an Allentown, Pennsylvania, team.

“Given the considerable maternal and neonatal morbidity associated with preeclampsia, an earlier diagnosis may theoretically decrease maternal and neonatal complications,” Dr. Christina Tun and colleagues with the Lehigh Valley Health Network comment in their paper in the American Journal of Obstetrics and Gynecology online June 13.

“Furthermore,” they add, “for patients that are ultimately not given the diagnosis of preeclampsia (the majority of women in our study), a shorter inpatient evaluation period would theoretically decrease cost by decreasing hospital stay by shortening the collection period.”

The researchers point out that preliminary studies have shown that a 12- hour collection and/or the protein:creatinine ratio may be adequate for the diagnosis of preeclampsia, but these approaches have not been tested prospectively.

They therefore compared the performance of a 12-hour urine protein cutoff of 165 mg and a protein:creatinine ratio of 0.15 to the standard 24-hour urine protein threshold of 300 mg or more in 90 women admitted with suspected preeclampsia.

Twenty-eight women had a 24-hour urine protein of at least 300 mg. The 12-hour level and the protein:creatinine ratio both correlated significantly with the 24-hour urine determination, the investigators found

Specifically, a 12-hour urine protein >165 mg predicted a 24-hour level of at least 300 mg with 96% sensitivity, 100% specificity, 100% positive predictive value, and 98% negative predictive value.

“Protein:creatinine ratio had reasonable sensitivity (89%) but lacked specificity (49%),” the authors report. However, with a negative predictive value of 91%, the test may be particularly useful in triaging women with mild hypertension, they suggest.

Overall, Dr. Tun and colleagues conclude, “Future studies should focus on development and prospective evaluation of a clinical algorithm incorporating both of these tools for the management of patients with suspected preeclampsia (both inpatient and outpatient), ideally correlating results with maternal and neonatal outcomes.”


Comparison of 12-hour urine protein and protein:creatinine ratio to 24-hour urine for the diagnosis of preeclampsia

Am J Obstet Gynecol 2012.