title: A practical approach to using spot urine protein/creatinine ratios for assessing proteinuria in pregnancy.
abstract: OBJECTIVE
  The aim of this study is to assess the diagnostic accuracy of the spot urine protein/creatinine ratio compared with the 24-hour urine protein in pregnancy.
  
  
  METHODS
  In this prospective cohort study of inpatient pregnant women, the protein/creatinine ratio and dipstick protein were assessed from a single urine sample collected at the start of the 24-hour urine. Both tests were compared with the 24-hour urine protein for correlation and test characteristics.
  
  
  RESULTS
  In the 196 specimens analysed, we found a strong correlation between the spot urine protein/creatinine ratio and 24-hour urine protein (r (2) = 0.78, P < 0.01). A protein/creatinine ratio <0.1 ruled out significant proteinuria (≥300 mg/day) with sensitivity and negative predictive value 100%. A protein/creatinine ratio ≥0.4 detected significant proteinuria (specificity and positive predictive value of 100%). A protein/creatinine ratio ≥4.6 had a specificity and positive predictive value of 100% for detecting severe proteinuria (≥5000 mg/day). Urine dipsticks correlated poorly with the 24-hour urine protein (r (2) = 0.40, P = 0.826). Nineteen percent of dipsticks reading nil or trace were false-negative results.
  
  
  CONCLUSIONS
  The spot urine protein/creatinine ratio correlated well with the 24-hour urine protein and performed better than the urine dipsticks. Significant proteinuria in pregnancy was excluded if the protein/creatinine ratio was <0.1 and identified when it was ≥0.4.
authors.affiliation: Department of Medicine.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Marnoch
authors.affiliation: Department of Medicine.
authors.forename: Lucia
authors.initials: L
authors.lastname: Larson
authors.affiliation: Division of Research, Department of Obstetrics and Gynecology and Community Health.
authors.forename: Sherry
authors.initials: S
authors.lastname: Weitzen
authors.affiliation: Division of Research, Department of Obstetrics and Gynecology and Community Health.
authors.forename: Maureen G
authors.initials: MG
authors.lastname: Phipps
authors.affiliation: Department of Pathology, Women and Infants Hospital of Rhode Island , Warren Alpert Medical School of Brown University , Providence RI , USA.
authors.forename: C James
authors.initials: CJ
authors.lastname: Sung
authors.affiliation: Department of Medicine.
authors.forename: Raymond O
authors.initials: RO
authors.lastname: Powrie
keywords: pregnancy; protein/creatinine ratio; proteinuria; sensitivity; specificity