Usage of spot urine protein to creatinine ratios in the evaluation of preeclampsia.
OBJECTIVE
The objective of the study was to prospectively compare spot urine protein to creatinine (P:C) ratios with 24 hour urine collections for protein in women being evaluated for preeclampsia.


METHODS
A spot urine P:C ratio was obtained at the beginning of 24 hour urine collections from 126 patients admitted to evaluate for preeclampsia. Correlation between the spot P:C ratio with the 24 hour urine collections was calculated. Receiver operator characteristic curves were constructed to determine best P:C cut-offs for 300 mg and 5000 mg protein per 24 hours.


RESULTS
Random spot P:C ratios were strongly correlated with 24 hour urine protein levels (Pearson r = 0.88). The optimal P:C cut-offs were 0.21 (300 mg per 24 hours) and 3.0 (5000 mg per 24 hours). A P:C ratio of less than 0.21 (300 mg per 24 hours) had a negative predictive value (NPV) of 83.3% and a P:C ratio of less than 3.0 (5000 mg per 24 hours) had 100% NPV.


CONCLUSIONS
Urine spot P:C ratio correlated well with 24 hour urine collections for protein but was not justified as a substitute for timed collections.
Wheeler
Thomas L
TL
Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL 35249-7333, USA. tlwheeler@uabmc.edu
Blackhurst
Dawn W
DW
Dellinger
Eric H
EH
Ramsey
Patrick S
PS
D000328:Adult; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D011225:Pre-Eclampsia / Q000175:diagnosis* / Q000652:urine; D011247:Pregnancy; D011446:Prospective Studies; D011507:Proteinuria / Q000175:diagnosis* / Q000209:etiology; D016482:Urinalysis / Q000379:methods*
D003404:Creatinine