title: Urinary protein-to-creatinine ratio in pregnant women after dipstick testing: prospective observational study.
abstract: 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.
authors.affiliation: Departments of Obstetrics and Gynecology, Jichi Medical University Hospital, Shimotsuke, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Baba
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Kita-ku N15 W7, Sapporo, 060-8638, Japan. taka0197@med.hokudai.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Departments of Obstetrics and Gynecology, University of Tsukuba Hospital, Tsukuba, Japan.
authors.forename: Mana
authors.initials: M
authors.lastname: Obata-Yasuoka
authors.affiliation: Departments of Obstetrics and Gynecology, Fukushima Medical University Hospital, Fukushima, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Yasuda
authors.affiliation: Departments of Obstetrics and Gynecology, Ohno Ladies Clinic, Iwakura, Japan.
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Ohno
authors.affiliation: Departments of Obstetrics and Gynecology, Hakodate Central General Hospital, Hakodate, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Kawabata
authors.affiliation: Departments of Obstetrics and Gynecology, Hiroshima University Hospital, Hiroshima, Japan.
authors.forename: Shiori
authors.initials: S
authors.lastname: Minakawa
authors.affiliation: Departments of Obstetrics and Gynecology, Juntendo University Hospital, Tokyo, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Hirai
authors.affiliation: Departments of Obstetrics and Gynecology, Mie Chuo Medical Center, Tsu, Japan.
authors.forename: Hideto
authors.initials: H
authors.lastname: Kusaka
authors.affiliation: Departments of Obstetrics and Gynecology, Mie University Hospital, Tsu, Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Murabayashi
authors.affiliation: Departments of Obstetrics and Gynecology, Nippon Medical School Tama Nagayama Hospital, Tama, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Inde
authors.affiliation: Departments of Obstetrics and Gynecology, Rakuwakai Otowa Hospital, Kyoto, Japan.
authors.forename: Michikazu
authors.initials: M
authors.lastname: Nagura
authors.affiliation: Departments of Obstetrics and Gynecology, University of Tsukuba Hospital, Tsukuba, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Hamada
authors.affiliation: Departments of Obstetrics and Gynecology, Juntendo University Hospital, Tokyo, Japan.
authors.forename: Atsuo
authors.initials: A
authors.lastname: Itakura
authors.affiliation: Departments of Obstetrics and Gynecology, Jichi Medical University Hospital, Shimotsuke, Japan.
authors.forename: Akihide
authors.initials: A
authors.lastname: Ohkuchi
authors.affiliation: Departments of Obstetrics and Gynecology, Mie Chuo Medical Center, Tsu, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Maeda
authors.affiliation: Departments of Obstetrics and Gynecology, Rakuwakai Otowa Hospital, Kyoto, Japan.
authors.forename: Norimasa
authors.initials: N
authors.lastname: Sagawa
authors.affiliation: Departments of Obstetrics and Gynecology, Nippon Medical School Tama Nagayama Hospital, Tama, Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Nakai
authors.affiliation: Departments of Obstetrics and Gynecology, Hakodate Central General Hospital, Hakodate, Japan.
authors.forename: Soromon
authors.initials: S
authors.lastname: Kataoka
authors.affiliation: Departments of Obstetrics and Gynecology, Fukushima Medical University Hospital, Fukushima, Japan.
authors.forename: Keiya
authors.initials: K
authors.lastname: Fujimori
authors.affiliation: Departments of Obstetrics and Gynecology, Hiroshima University Hospital, Hiroshima, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kudo
authors.affiliation: Departments of Obstetrics and Gynecology, Mie University Hospital, Tsu, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Ikeda
authors.affiliation: Department of Obstetrics, Hokkaido University Graduate School of Medicine, Kita-ku N15 W7, Sapporo, 060-8638, Japan.
authors.forename: Hisanori
authors.initials: H
authors.lastname: Minakami
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000175:diagnosis*; D008875:Middle Aged; D016017:Odds Ratio; D011225:Pre-Eclampsia / Q000175:diagnosis*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis*; D011446:Prospective Studies; D011507:Proteinuria / Q000175:diagnosis*; D016482:Urinalysis; D055815:Young Adult
chemical_list: D003404:Creatinine