Urinary protein-to-creatinine ratio indicative of significant proteinuria in normotensive pregnant women.
OBJECTIVE
In hypertensive pregnant women, the protein-to-creatinine (P/C) ratio is well correlated with 24-h proteinuria and a P/C ratio of 0.27 (g/gCr) is used to reflect significant proteinuria (>0.3 g/day). The aim of this study was to obtain data on normotensive pregnant women, which have so far been lacking.


METHODS
The study population consisted of 74 pregnant women who met the following criteria: (i) ≥22 gestational weeks; (ii) a positive result (≥1+) on dipstick test; (iii) a positive result (>0.27) for P/C ratio; and (iv) 24-h urine test performed within 2 days of the P/C ratio. The correlation between the P/C ratio and 24-h proteinuria, the incidence rates of significant proteinuria according to P/C ratios, and appropriate threshold of the P/C ratio to rule in significant proteinuria were determined using the appropriate statistical methods.


RESULTS
The P/C ratio was moderately correlated with the 24-h proteinuria, with a correlation coefficient of 0.64 (95% confidence interval, 0.487-0.76). The area under the receiver-operator curve was 0.76 (95% confidence interval, 0.66-0.87); however, no clear shoulder was identifiable. The incidence rates of significant proteinuria according to P/C ratios of 0.27-0.49, 0.50-0.74, 0.75-0.99, and >1 were 41, 66, 100, and 100%, respectively, indicating that all normotensive pregnant women with a P/C ratio > 0.75 had significant proteinuria.


CONCLUSIONS
Normotensive pregnant women showed a significant correlation between the P/C ratio and 24-h urine protein level. All normotensive pregnant women with a P/C ratio > 0.75 had significant proteinuria, suggesting that a P/C ratio > 0.75 may be the 'rule-in' threshold of significant proteinuria in this population.
Department of Obstetrics and Gynecology, Jichi Medical University, Shimotsuke, Japan.
Yosuke
Y
Baba
Department of Obstetrics and Gynecology, Jichi Medical University, Shimotsuke, Japan.
Akihide
A
Ohkuchi
Department of Obstetrics and Gynecology, Jichi Medical University, Shimotsuke, Japan.
Rie
R
Usui
Department of Obstetrics and Gynecology, Jichi Medical University, Shimotsuke, Japan.
Hironori
H
Takahashi
Department of Obstetrics and Gynecology, Jichi Medical University, Shimotsuke, Japan.
Shigeki
S
Matsubara
D000293:Adolescent; D000328:Adult; D003404:Creatinine / Q000652:urine*; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011507:Proteinuria / Q000175:diagnosis* / Q000652:urine*; D012372:ROC Curve; D012189:Retrospective Studies; D055815:Young Adult
D003404:Creatinine
pre-eclampsia; protein-to-creatinine ratio; proteinuria