Journal of Perinatology (2008) 28, 461–467 r 2008 Nature Publishing Group All rights reserved. 0743-8346/08 $30 www.nature.com/jp ORIGINAL ARTICLE Urinalysis vs urine protein–creatinine ratio to predict significant proteinuria in pregnancy

BK Dwyer1, M Gorman2, IR Carroll3 and M Druzin1 1Division of Maternal Fetal , Department of Gynecology and , Stanford University, Stanford, CA, USA; 2Department of Family and Community Medicine, University of California, Davis, CA, USA and 3Division of Pain Medicine, Department of , Stanford University, Stanford, CA, USA

evaluation. A rapid screening test to predict 24-h proteinuria, in Objective: To compare the urine protein–creatinine ratio with urinalysis combination with other presenting signs and symptoms, can help a to predict significant proteinuria (X300 mg per day). clinician determine the appropriate amount of surveillance and Study Design: A total of 116 paired spot urine samples and 24-h urine guide care during the initial 24-h period. Traditionally, the dipstick 2 collections were obtained prospectively from women at risk for urinalysis has been used as this screening test. preeclampsia. Urine protein–creatinine ratio and urinalysis were The dipstick urinalysis measures the concentration of protein in compared to the 24-h urine collection. the urine and is susceptible to fluctuations in the water content of the urine. Dilute urine may underestimate the amount of protein Result: The urine protein–creatinine ratio had better discriminatory that would be collected in a 24-h urine collection, whereas power than urinalysis: the receiver operating characteristic curve had a concentrated urine may overestimate it. Prior studies have reported greater area under the curve, 0.89 (95% confidence interval (CI) 0.83 to that dipstick urinalysis has varying degrees of accuracy, with 0.95) vs 0.71 (95% CI 0.64 to 0.77, P<0.001). When matched for sensitivities ranging from 22 to 82%. Specificities also vary clinically relevant specificity, urine protein–creatinine ratio (cutoff widely.2–5 Differences in methodology contribute to this large X0.28) is more sensitive than urinalysis (cutoff X1 þ ): 66 vs 41%, discrepancy. For example, automated dipstick urinalysis is more P ¼ 0.001 (with 95 and 100% specificity, respectively). Furthermore, the specific for predicting 24-h proteinuria than is ward dipstick urine protein–creatinine ratio predicted the absence or presence of urinalysis.6 Furthermore, discrepancies in the reported sensitivity proteinuria in 64% of patients; urinalysis predicted this in only 19%. and specificity of the dipstick urinalysis may be due to differences Conclusion: The urine protein–creatinine ratio is a better screening in the spectrum of illness in the populations studied or the time of test. It provides early information for more patients. day that the spot urine was collected. Journal of Perinatology (2008) 28, 461–467; doi:10.1038/jp.2008.4; Recently, the urine protein–creatinine ratio has been published online 21 February 2008 considered important for predicting proteinuria. It compares the spot urine protein excretion to the spot urine creatinine excretion, Keywords: pregnancy; urinalysis; urine protein–creatinine ratio; proteinuria; preeclampsia; sensitivity and specificity thereby normalizing protein excretion to the glomerular filtration rate. Thus, the urine protein–creatinine ratio is not subject to variation due to hydration status. In pregnant women, the urine protein–creatinine ratio and the 24-h urine are highly Introduction correlated.6–13 Many studies have evaluated the urine protein– The diagnosis of preeclampsia is determined by the presence of creatinine ratio but, they differ in their recommended cutoffs and elevated blood pressure and significant proteinuria (X300 mg per 6–9,12,13 1 differ in their assessment of the test’s utility. Different 24 h) after the 20th week of gestation. The gold standard for methodologies, such as the spectrum of illness in the population measuring proteinuria is the 24-h urine collection. Unfortunately, studied, retrospective study design,9 exclusion of patients with the 24-h urine collection takes an entire day to collect and is, comorbid illness,9,13 and nonexclusion of incomplete or infected therefore, not available to guide clinical decisions upon first samples6–13 probably account for these discrepancies. Correspondence: Dr BK Dwyer, Division of Maternal Fetal Medicine, Department of No study has directly compared the diagnostic ability of the Gynecology and Obstetrics, Stanford University, 300 Pasteur Drive, Stanford, CA 94305-5317, automated dipstick urinalysis to that of the urine protein– USA. creatinine ratio using the same group of subjects, which would E-mail: [email protected] Received 4 June 2007; revised 19 December 2007; accepted 4 January 2008; published online allow appropriate statistical comparisons. In this study, we directly 21 February 2008 compared the two tests in a prospective fashion on a group of Urinalysis and protein–creatinine ratio BK Dwyer et al 462 women being evaluated for preeclampsia, including those with respectively. The automated dipstick urinalysis was performed with comorbid illness to determine which was more predictive of 24-h Iris test strips and either the IRIS 500 (IRIS Inc., Chatsworth, CA, proteinuria. USA) or Autionmax (Arcray Inc., Kyoto, Japan), autoanalyzers using 3030050500-tetrachlorophenol-3,4,5,6-tetrabromosulfopthalein, a protein error of pH indicator. These machines were calibrated Methods such that 1 þ protein ¼ 30 mg per 100 ml, 2 þ protein ¼ 100 mg This prospective study was performed on the Labor and Delivery per 100 ml, 3 þ protein ¼ 300 mg per 100 ml and unit at Stanford University Hospital from September 2002 to March 4 þ protein ¼ 1000 mg per 100 ml. Trace protein was not reported 2004 after approval by the Institutional Review Board, Medical by these machines. All measurements were performed by laboratory Human Subjects Panel. Written informed consent was obtained technicians blinded to the clinical status of the study patients. from all participating patients. To mimic the experience of treating we included all women being evaluated for Statistical analysis preeclampsia, regardless of the alerting sign or symptom, suspected The strengths of the correlation between the automated dipstick severity or comorbid conditions. Study patients underwent initial urinalysis and 24-h proteinuria and the urine protein–creatinine triage on the Labor and Delivery unit. Most women completed the ratio and 24-h proteinuria were determined by Spearman’s correlation 24-h urine collection as outpatients, but some remained in the unit coefficients with corresponding 95% confidence intervals (CI). as clinically indicated. The study design allowed for patients to be Significant proteinuria was defined as X300 mg of protein in enrolled when they presented to Labor and Delivery for an the 24-h urine collection, as recommended by the International independent evaluation of preeclampsia. Therefore, women could Society for the Study of Hypertension in Pregnancy and the 1,15 be enrolled more than once. There were 155 enrollments. Of these, American College of Obstetrics and Gynecology. The sensitivity 16 19 were excluded because the 24-h urine was not done, 4 because and specificity as well as the positive and negative predictive 17 the urinalysis was not done and 6 because the urine protein– values were calculated using each observed level of the urinalysis creatinine ratio was not done. Six were excluded because the 24-h and the urine protein–creatinine ratio as the threshold for a urine was not complete or the collection was improper by the positive test with the 24-h collection as the reference standard. criteria below. Four were excluded because the urinalysis had>10 Differences in selected sensitivities and specificities were examined white blood cells (WBCs) per high-power field (h.p.f.) on using the McNemar’s test. The likelihood ratios (LRs) for ranges of 18 microscopy, concerning for contamination. A total of 116 the urine protein–creatinine ratio and urinalysis were calculated. enrollments from 95 women were ultimately included in the study. Additionally, we examined the test characteristics for predicting a Thus, 21 of the 116 samples were from women who were enrolled severe level of proteinuria of 5000 mg or greater. in the study more than once. The relationship between sensitivity and the false-positive rate The main measures were the urinary protein concentration (1Àspecificity) for both the urinalysis and the urine protein– by automated dipstick urinalysis, the urinary protein to urinary creatinine ratio was evaluated by constructing receiver operating creatinine ratio by random (spot) direct measurement and the characteristic (ROC) curves for both measures. As a summary of 24-h urinary protein excretion by a 24-h urine collection. The the diagnostic utility of the urinalysis and the urine protein– urinalysis and the urine protein–creatinine ratio were usually creatinine ratio, the areas under the ROC curves were calculated obtained immediately before the 24-h urine collection was begun. and directly compared using the method described by Delong 19 If that sample was not available at the time of enrollment, a et al. Data analysis was performed using STATA statistical sample was obtained immediately after the 24-h collection. All software (Release 8; Stata Corp., College Station, TX, USA). samples were collected via clean catch unless the membranes had To examine whether a lack of independence due to some been ruptured, in which case specimens were obtained by catheter. subjects contributing more than one set of paired spot urine and Given that outpatient and inpatient urine collections may have 24-h urine samples led to inaccurate estimates in our analysis, been collected with different degrees of completeness and/or a sensitivity analysis was performed comparing the statistical contamination, subjects were excluded if the urinalysis contained outcome of the data from the initial 116 samples to that of 95 >10 WBCs per h.p.f., if a catheter was not used after membrane samples (using only first samples if there had been additional rupture or if an outpatient 24-h urine collection was incomplete. enrollments). A complete collection was defined as having a total creatinine of >1000 mg (850 mg for obese women) or a total creatinine of 13 mg per kg body weight.14 Results The urinary protein and creatinine were measured using Population studied Synchron LX Systems (Beckman Coulter Inc., Fullerton, CA, USA), A total of 116 paired samples were evaluated. Of those 48% had which uses the pyrogallol red/molybdate and Jaffe rate methods, significant proteinuria. Forty-one percent were from primigravidas.

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In total, 41% of the samples were from Caucasian women, 31% sensitivity to maximum specificity. Note that ‘trace’ proteinuria is from Hispanic women, 16% from Asian women and 12% from not reported by automated dipstick machines. African-American women. Many subjects had medical conditions The sensitivity for the urine protein–creatinine ratio varied that predisposed them to preeclampsia (Table 1). depending on the cutoff used. We highlight two clinically useful cutoffs derived from the ROC curve, one that maximizes sensitivity Correlation of the urine protein–creatinine ratio vs the and the other that maximizes specificity. A cutoff of X0.15 had a urinalysis to 24-h proteinuria sensitivity of 96% (95% CI 87 to 99%) and a specificity of 53% (95% Both the urine protein–creatinine ratio and the urinalysis were CI 40 to 66%). A cutoff of X0.28 had a sensitivity of 66% (95% CI correlated to the gold standard, 24-h proteinuria. The correlation 52 to 78%) and a specificity of 95% (95% CI 86 to 99%). Note that coefficient for the urine protein–creatinine ratio was 0.83 (95% CI a cutoff of X0.19 maximizes both sensitivity (89, 95% CI 78 to 0.76 to 0.88). For the urinalysis, it was 0.64 (95% CI 0.52 to 0.74). 96%) and specificity (70, 95% CI 59 to 83%), but significantly compromises both measures. Receiver operating characteristic curves The sensitivity for the urinalysis ranged from 11 to 41% The ROC curves for both the urine protein–creatinine ratio and depending on the cutoff used (Table 2). Greater than or equal to the urinalysis are presented in Figure 1. A diagnostic test with an area under the ROC curve closest to 1.0 has the best discriminatory power. The area under the ROC curve for the urine protein– creatinine ratio was 0.89 (95% CI 0.83 to 0.95), and the area under the ROC curve for the urinalysis was 0.71 (95% CI 0.64 to 0.77). The areas under these curves were significantly different (P<0.001).

Sensitivity and specificity of the urine protein–creatinine ratio and the urinalysis for predicting significant proteinuria (X300 mg proteinuria per 24-h period) The urine protein–creatinine ratio is the more sensitive test for predicting 24-h proteinuria compared to the urinalysis, even when matched for specificity. Table 2 demonstrates the sensitivity and specificity for both tests at selected cutoffs. These points were selected because they demonstrate the range from maximum

Table 1 Demographic and clinical characteristics of study participants by presence or absence of significant proteinuria in a 24-h urine collection (n ¼ 116)

Characteristic <300 mg protein per X300 mg protein per 24 h (n ¼ 60) 24 h (n ¼ 56)

Age, mean (s.d.) 30.8 (6.2) 30.8 (6.5) Caucasian, no. (%) 25 (41.7) 22 (39.3) Primigravida, no. (%) 19 (32.7) 22 (39.3) Weight lbs, mean (s.d.) 189.5 (37.1) 193.9 (41.5) High systolic blood pressure, 141.4 (13.1) 143.4 (16.3) mean (s.d.) High diastolic blood pressure, 89.3 (11.3) 91.5 (12.8) mean (s.d.) Chronic hypertension, no. 10 (16.7) 16 (28.6) (%) Diabetes mellitusa, no. (%) 7 (11.7) 1 (1.8) Figure 1 Receiver operating characteristic curves (ROCs) for the urine protein– Total 24-h protein, median 210 (165–242) 580 (390–1246) creatinine ratio (a) and for the urinalysis (b). The area under the ROC curve for the urine protein–creatinine ratio is 0.89 (95% CI 0.83 to 0.95) and the area (IQR) mg under the ROC curve for the urinalysis is 0.71 (95% CI 0.64 to 0.77). The areas Abbreviations: IQR, interquartile range; lbs, pounds. under these curves are significantly different (P<0.001). Selected values for each aIncludes pregestational and gestational diabetes. measure, along with the sensitivity or specificity, are highlighted.

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Table 2 Sensitivity, specificity, positive predictive value and negative predictive Table 3 Likelihood ratios for the urine protein–creatinine ratio and the value for selected cutoffs for the urine protein–creatinine ratio and the urinalysis urinalysis for different ranges of test results for predicting X300 mg protein per 24 h urine Test result Likelihood ratioa (95% CI) Interpretation Test result Sensitivity (%) Specificity (%) PPV (%) NPV (%) UPCR UPCR <0.15 0.07 (0.02–0.27) Negative X0.15a 96 53 66 94 0.15–0.27 0.73 (0.44–1.2) Indeterminate X0.17 91 58 67 88 X0.28 13.21 (4.3–40.5) Positive X0.19 89 70 74 88 X0.24 73 87 84 78 UA X0.28 66 95 93 75 Negative 0.59 (0.47–0.73) Indeterminate X0.39 55 100 100 71 X1+ 49.29 (3.1–792.8) Positive

Abbreviations: UA, urinalysis; UPCR, urine protein–creatinine ratio. UA a0.05 was added to empty cells to allow for the calculation of the likelihood ratios. XNegative 100 0 48 –b X1+ 41 100 100 65 X2+ 23 100 100 58 X3+ 11 100 100 55 However, values of the urine protein–creatinine ratio from 0.15 to 0.27 (LR ¼ 0.73, 95% CI 0.44 to 1.20) and a negative urinalysis Abbreviations: UA, urinalysis; UPCR, urine protein–creatinine ratio. a (LR 0.59, 95% CI 0.47 to 0.73) do not significantly affect pretest Using a cutoff of X0.15, two subjects with significant 24-h proteinuria (304 and ¼ 336 mg) were missed. probability. Therefore, urine samples with these results are bThis number could not be calculated due to 0 in the denominator. indeterminate. Thus, the urine protein–creatinine ratio is useful diagnostically when the value is <0.15 or X0.28, but is indeterminate in the middle range. Similarly, the urinalysis is useful when the value is 1 þ proteinuria on the dipstick had a sensitivity of 41% (95% CI X1 þ protein, but is indeterminate when it is negative for protein. 28 to 55%) and a specificity of 100% (95% CI 93 to 100%). In our study the urine protein–creatinine ratio was diagnostic in These data demonstrate that when using a cutoff of X0.15, the 64% our samples, whereas, the urinalysis was diagnostic in only urine protein–creatinine ratio is significantly more sensitive than 19% of our samples (P<0.001). the urinalysis (96 vs 41%, P<0.001). Even when matching the two tests for clinically relevant specificity with a urine protein– Sensitivity and specificity of the urine protein–creatinine ratio creatinine ratio cutoff of X0.28 and a urinalysis cutoff of X1 þ and the urinalysis for predicting severe proteinuria (specificity is 95 and 100%, respectively), the sensitivity of the urine (X5000 mg proteinuria per 24-h period) protein–creatinine ratio is better than that of the urinalysis (66 vs Sensitivities, specificities and positive and negative predictive values 41%, P ¼ 0.001). were calculated for many cutoffs of the urine protein–creatinine ratio and each cutoff of the urinalysis to demonstrate the accuracy Likelihood ratios for the urine protein–creatinine ratio and the of each test for predicting X5000 mg proteinuria per 24-h period urinalysis (Table 4 ). Only three patients in our study had proteinuria Unlike predictive values, LRs are less subject to variation in the X5000 mg of protein. As a screening test for identifying patients 17 prevalence of disease in a given population. We list the LRs for who may have severe proteinuria, the urine protein–creatinine ranges of each test (Table 3). In general, a diagnostic test with an ratio and the urinalysis are very good. They also both have good LR of>10 or <0.10 changes pretest probability dramatically and is specificity, in particular the urine protein–creatinine ratio X5.0 20 considered a strong diagnostic test. and the urinalysis X3 þ . In fact, to predict severe proteinuria it Likelihood ratios calculated for values of the urine protein– appears that the urine protein–creatinine ratio is unlikely to add creatinine ratio <0.15 and X0.28 have a large effect on pretest utility to the urinalysis alone. Caution should be used in using spot probability. For example, with a urine protein–creatinine ratio of urine studies rather than 24-h urine collections to make a <0.15 (LR ¼ 0.07, 95% CI 0.02 to 0.27), pretest probabilities of 40, diagnosis of severe proteinuria because this analysis is limited by 50 and 60% transform to posttest probabilities of 4, 6 and 9%, the relatively few number of patients with severe proteinuria in this respectively. Similarly, with values X0.28 (LR ¼ 13.2, 95% CI 4.3 study and, therefore, the inability to accurately describe a range. to 40.1), pretest probabilities of 40, 50 and 60% transform to posttest probabilities of 90, 93 and 95%, respectively. A urinalysis of Sensitivity analysis X1 þ (LR ¼ 49.7, 95% CI 3.1 to 792.3) also has an LR that is Given concern that 21 paired samples from our cohort were from strongly diagnostic. patients who previously contributed samples, we conducted a

Journal of Perinatology Urinalysis and protein–creatinine ratio BK Dwyer et al 465 sensitivity analysis comparing the results of our initial cohort to the coefficients, the area under the ROC curves, sensitivity and cohort minus these 21 samples. Each statistic reported above was specificity for chosen cutoffs, and LRs for chosen ranges. All of calculated for each group, including Spearman’s correlation these test results were identical or nearly identical to the values calculated for the entire study group. As expected, the CIs around sensitivity, specificity and LRs were slightly wider for the group with Table 4 Sensitivity, specificity, positive predictive value and negative predictive value for selected cutoffs for the urine protein–creatinine ratio and the urinalysis fewer samples. for predicting X5000 mg protein per 24 h urine

Test result Sensitivity (%) Specificity (%) PPV (%) NPV (%) Discussion UPCR Our study demonstrated that the urine protein–creatinine ratio X2 100 96 38 100 can be more sensitive than the automated dipstick urinalysis, and X3 100 97 50 100 therefore, is the better screening test (96 vs 41%, P<0.001). The X 4 100 98 60 100 urinalysis is very specific, but at its most sensitive diagnostic level X5 100 100 100 100 (1 ) will miss more than half (59%) of patients at risk for X13.53 67 100 100 99 þ preeclampsia. The urine protein–creatinine ratio also allows for UA early diagnosis in more patients (64 vs 19%, P<0.001). XNegative 100 0 3 –a Other studies have previously evaluated the urine protein– X1+ 100 83 14 100 creatinine ratio in pregnancy for its ability to predict 24-h 6–9,12,13 X2+ 100 92 25 100 proteinuria at different cutoffs. Our data are nearly X3+ 100 98 60 100 identical to studies that evaluated a similar patient population, and Abbreviations: UA, urinalysis; UPCR, urine protein–creatinine ratio. therefore, should be applicable to institutions screening individuals 7–9,13 aThis number could not be calculated due to 0 in the denominator. who are clinically suspicious for preeclampsia. Despite the

Figure 2 Flow diagram of the two-step triage strategy. At triage, an automated dipstick urinalysis should be performed. If it is positive, a patient can be assumed to have significant proteinuria. If it is negative, the test is indeterminate and a urine protein–creatinine ratio should be performed to further define risk. In parentheses are the number of samples in the current study that fell into each category. UPCR, urine protein–creatinine ratio.

Journal of Perinatology Urinalysis and protein–creatinine ratio BK Dwyer et al 466 similarity in data, conclusions regarding the ‘optimal cutoff’ and dipstick urinalysis alone. With the traditional urinalysis, using the whether the urine protein–creatinine ratio is useful have X1 þ as a cutoff, the presence of significant proteinuria was varied. This is because an ‘optimal cutoff’ that simultaneously predicted in only 19% of our subjects prior to 24-h urine collection. maximizes sensitivity and specificity (0.19 in our case) A negative urinalysis cannot predict the absence of significant significantly compromises each measure. We recommend using proteinuria (LR ¼ 0.59, 95% CI 0.47 to 0.73). Using the urinalysis two cutoffs. A cutoff of X0.15 will increase sensitivity to well above combined with the urine protein–creatinine ratio, the absence or 90%, and a cutoff of X0.28 will maximize specificity. The urine presence of significant proteinuria was predicted in 66% of patients. protein–creatinine ratio cutoff is thus dictated by the In summary, the urine protein–creatinine ratio may be a ’s needs. useful adjunct test for diagnosis and triage of a patient being Our study has limitations. A small number of our spot samples evaluated for preeclampsia. Its use as an initial screen in were collected immediately after the 24-h urine specimen rather combination with the urinalysis will prevent underdiagnosis of than before. We do not think that this alters our ability to compare preeclampsia and provide an accurate diagnosis 66% of the time the two tests given that the paired urinalysis and urine protein– before a 24-h collection is completed. Earlier distinction between creatinine ratios were collected at the same time in relation to the preeclampsia and other forms of hypertension in triage may allow 24-h urine collection. Therefore, the direct comparison between the for earlier diagnosis and treatment of preeclampsia with a two tests was achieved because the timing of the sample collection subsequent decrease in morbidity and a decrease in resource was consistent within subjects. It is also important to emphasize utilization. that these results demonstrate that the urine protein–creatinine ratio can detect significant 24-h proteinuria (X300 mg per 24 h) better than the urinalysis, but this study does not address whether the urine protein–creatinine ratio can distinguish between mild Acknowledgments and severe preeclampsia by predicting the extent of proteinuria. A This study was financially supported by the Department of Gynecology and 24-h urine may still be needed in settings where the diagnosis of Obstetrics, Stanford University. preeclampsia or severe preeclampsia by proteinuria would imply a preterm delivery. Concern has been raised that the urine protein–creatinine ratio may be effected by body type or by race, as people with higher References muscle mass have more total urinary creatinine excretion and 1 ACOG Committee on Obstetric Practice. ACOG practice bulletin. Diagnosis and nonpregnant African Americans may have a higher concentration of management of preeclampsia and eclampsia. Number 33, January 2002. American urine creatinine. It is unclear how these differences effect the validity College of Obstetricians and Gynecologists. Int J Gynaecol Obstet 2002; 77: 67–75. of the urine protein–creatinine ratio in different subpopulations.21 2 Meyer NL, Mercer BM, Friedman SA, Sibai BM. Urinary dipstick protein: a poor Unfortunately, our study was underpowered to conduct appropriate predictor of absent or severe proteinuria. Am J Obstet Gynecol 1994; 170: 137–141. 3 Waugh JJ, Clark TJ, Divakaran TG, Khan KS, Kilby MD. Accuracy of urinalysis dipstick stratified analyses by race/ethnicity to address these issues. Future techniques in predicting significant proteinuria in pregnancy. Obstet Gynecol 2004; studies should be done to address these variations. 103: 769–777. On the basis of our study results, we recommend a two-step 4 Kuo VS, Koumantakis G, Gallery ED. Proteinuria and its assessment in normal and triage algorithm to identify patients with preeclampsia (Figure 2). hypertensive pregnancy. Am J Obstet Gynecol 1992; 167: 723–728. On initial screen, an automated dipstick urinalysis should be 5 Brown MA, Buddle ML. Inadequacy of dipstick proteinuria in hypertensive pregnancy. Aust N Z J Obstet Gynaecol 1995; 35: 366–369. performed. If the urinalysis has 1 þ protein or greater, the patient 6 Saudan PJ, Brown MA, Farrell T, Shaw L. Improved methods of assessing proteinuria in most likely has significant proteinuria. If the urinalysis is negative hypertensive pregnancy. Br J Obstet Gynaecol 1997; 104: 1159–1164. for protein (an indeterminate result), a urine protein–creatinine 7 Rodriguez-Thompson D, Lieberman ES. Use of a random urinary protein-to-creatinine ratio should be ordered to further define risk. If the urine protein– ratio for the diagnosis of significant proteinuria during pregnancy. Am J Obstet creatinine ratio is <0.15, the patient most likely does not have Gynecol 2001; 185: 808–811. significant proteinuria. In this setting, whether the 24-h urine 8 Young RA, Buchanan RJ, Kinch RA. Use of the protein/creatinine ratio of a single voided urine specimen in the evaluation of suspected pregnancy-induced hypertension. collection is still an appropriate test is debatable and may not be J Fam Pract 1996; 42: 385–389. cost effective. If the urine protein–creatinine ratio is X0.28, the 9 Al RA, Baykal C, Karacay O, Geyik PO, Altun S, Dolen I. Random urine protein– patient most likely has significant proteinuria. If the urine creatinine ratio to predict proteinuria in new-onset mild hypertension in late protein–creatinine ratio is between 0.15 and 0.27, this is an pregnancy. Obstet Gynecol 2004; 104: 367–371. indeterminate result and further evaluation with a 24-h urine 10 Robert M, Sepandj F, Liston RM, Dooley KC. Random protein–creatinine ratio for the quantitation of proteinuria in pregnancy. Obstet Gynecol 1997; 90: 893–895. collection is warranted. 11 Neithardt AB, Dooley SL, Borensztajn J. Prediction of 24-h protein excretion in This diagnostic algorithm is better at providing more accurate pregnancy with a single voided urine protein-to-creatinine ratio. Am J Obstet Gynecol and earlier diagnostic information than the traditional automated 2002; 186: 883–886.

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