Journal Article Urinary protein-to-creatinine ratio in pregnant women after dipstick testing : prospective observational study

Baba, Yosuke  ,  Yamada, Takahiro  ,  Obata-Yasuoka, Mana  ,  Yasuda, Shun  ,  Ohno, Yasumasa  ,  Kawabata, Kosuke  ,  Minakawa, Shiori  ,  Hirai, Chihiro  ,  Kusaka, Hideto  ,  Murabayashi, Nao  ,  Inde, Yusuke  ,  Nagura, Michikazu  ,  Hamada, Hiromi  ,  Itakura, Atsuo  ,  Ohkuchi, Akihide  ,  Maeda, Makoto  ,  Sagawa, Norimasa  ,  Nakai, Akihito  ,  Kataoka, Soromon  ,  Fujimori, Keiya  ,  Kudo, Yoshiki  ,  Ikeda, Tomoaki  ,  Minakami, Hisanori

15p.331 , 2015-12-14 , BioMed Central
Background: The dipstick test is widely used as a primary screening test for detection of significant proteinuria in pregnancy (SPIP). However, it often shows a false positive test result. This study was performed to determine which pregnant women should be recommended to undergo determination of urinary protein-to-creatinine ratio (mg/mg, P/Cr test) after dipstick test for confirmation of SPIP. Methods: This was a multicenter, prospective, and observational study of 2212 urine specimens from 1033 pregnant women who underwent simultaneous dipstick and P/Cr tests in the same spot urine samples at least once. SPIP was defined as P/Cr > 0.27. Preeclampsia was diagnosed in women with both hypertension and SPIP. Results: Preeclampsia, hypertension alone, and SPIP alone developed in 202 (20 %), 73 (7.1 %), and 120 (12 %) women, respectively. Creatinine concentration [Cr] varied greatly, ranging from 8.1 to 831 mg/dL in the 2212 urine samples. Rate of positive dipstick test results increased with increasing [Cr], while SPIP prevalence rate was lower in urine samples with higher [Cr], yielding higher false positive rates in samples with higher [Cr]. Postpartum urine samples had significantly lower [Cr] compared to those obtained antepartum (60 [8.7-297] vs. 100 [10-401] mg/dL, respectively). At the first P/Cr test among women with similar dipstick test results, the risk of having SPIP was consistently and significantly higher for hypertensive women than for normotensive women at any dipstick test result: 18 % (14/77) vs. 3.2 % (8/251), 47 % (26/55) vs. 8.7 % (37/425), 91 % (82/90) vs. 59 % (44/75) for negative/equivocal, 1+, and >= 2+ test results, respectively. The risk of SPIP was 16 % (9/55) for normotensive women when two successive antenatal urine samples showed a dipstick test result of 1 +. Conclusions: For prediction of SPIP, the dipstick test was more likely to show a false positive result in concentrated urine samples with higher [Cr]. Hypertensive women with >= 1+ as well as normotensive women with >= 2+ on dipstick test should be advised to undergo the P/Cr test.

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