Random albumin/creatinine ratio for quantification of proteinuria in manifest pre-eclampsia

Correlation between Random Urinary Protein-to-creatinine Ratio and 24-h Urinary Protein Excretion in Preeclampsia

This study aimed to determine the correlation between random urinary protein-to-creatinine ratio in single-voided urine samples and 24-h urinary protein excretion in pregnant women with preeclampsia. A cross-sectional study was conducted at the Department of Gynecology and Obstetrics, Abbasi Shaheed Hospital, Karachi, Pakistan, from July 2019 to June 2020. Fifty women with singleton pregnancy after 20 weeks of gestation with hypertension and 2+ proteinuria or more, according to a dipstick test, were included. Those with chronic hypertension; preexisting renal disease; gestational diabetes; eclampsia; hemolysis, elevated liver enzymes, a low platelet count syndrome; and coexisting urinary tract infections were excluded. Two random urine samples taken at 9:00 a.m. and 2:00 p.m. and 24-h urine samples were collected to evaluate the random urinary protein-to-creatinine and the 24-h protein excretion, respectively. The correlation coefficient (r) between them was calculated using Pearson's correlation test. The patients' mean age was 28.58 ± 5.09 years and their mean gestational age was 32.74 ± 4.44 weeks. Twenty-eight (56%) women were primigravidas, and 22 (44%) were multiparous. The average serum creatinine was 0.80 ± 0.16 mg/dL. The mean random urinary protein-to-creatinine ratio was 0.93 ± 0.7 mg/mg, and the mean 24-h urine was 481.08 ± 20.10 mL. A strong positive correlation was found between the protein-to-creatinine ratio and 24-h urinary protein excretion (r = 0.655; P = 0.01). We concluded that the protein-to-creatinine ratio in spot urine samples could be used as an alternative to in 24-h collection of urine to determine protein excretion in preeclamptic pregnant women.

Impact of random urine proteinuria on maternal and fetal outcomes of pregnancy: a retrospective case-control study

BACKGROUND/AIMS

Proteinuria is associated with hypertension and preeclampsia in pregnancy. However, the impact of random urine proteinuria on fetal and maternal outcomes has not been established. We investigated the influence of random urine proteinuria on the clinical outcomes of pregnancy.

METHODS

From January 2008 to December 2010, 2,822 patients were retrospectively studied. A total of 536 pregnant women with proteinuria in random urine and matched controls without proteinuria via propensity score matching were analyzed. Proteinuria was checked by the dipstick method.

RESULTS

The patients' mean age was 33.0 ± 4.7 years, and the mean gestational age was 235.6 ± 50.6 days on admission. The prevalence of hypertension and chronic kidney disease was 2.4% (n = 67) and 1.0% (n = 29), respectively. Women with random urine proteinuria showed higher blood urea nitrogen levels and a higher incidence of hematuria. These women also had a higher incidence of preeclampsia, preterm labor, premature rupture of membranes, and intrauterine growth restriction. Proteinuria was strongly correlated with preeclampsia in both propensity score matching (p < 0.001, r = 0.783) and unmatched whole samples (p < 0.001, r = 0.851).

CONCLUSIONS

These findings suggest that random urine proteinuria is associated with preeclampsia, preterm labor, premature rupture of membrane, and intrauterine growth restriction.

Spot Urine Protein-to-Creatinine Ratio to Predict the Magnitude of 24-Hour Total Proteinuria in Preeclampsia of Varying Severity

OBJECTIVE

The predictive value of spot urine protein-to-creatinine ratio (PCR) for estimating total 24-hour proteinuria in severe preeclampsia is unclear. This study aimed to assess the diagnostic accuracy of spot urine PCR for ascertaining the magnitude of proteinuria in women with preeclampsia of varying severity.

METHODS

A total of 205 patients with prediagnosed preeclampsia were included in this prospective cohort study. Patients were allocated into one of the three groups categorized by severity of disease, as follows: gestational hypertension, group 1 (n = 41); preeclampsia, group 2 (n = 88); and severe preeclampsia, group 3 (n = 76). We assessed the spot urine PCRs to determine significant proteinuria and the magnitude of proteinuria in these groups.

RESULTS

The spot urine PCR was 0.53, with 81% sensitivity and 93% specificity to detect significant proteinuria. A significant correlation was found between PCR and 24-hour total proteinuria in group 1 (r = 0.473, P = 0.002). There were also significant correlations in group 2 (r = 0.814, P < 0.001) and group 3 (r = 0.912, P < 0.001). The established formula using spot urine PCR to estimate 24-hour total proteinuria in severe preeclampsia was Y = 832.02X + 378.74 mg (r² = 0.8304).

CONCLUSION

Although 24-hour urine collection remains a merely reliable test to determine the degree of total proteinuria, our findings suggest that it is likely to assess the magnitude of proteinuria by the spot urine PCR, especially in severe preeclampsia.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.govNCT01623791.

The value of the urinary protein:creatinine ratio for the detection of significant proteinuria in women with suspected preeclampsia

To explore the correlation between urinary protein:creatinine ratio and 24-h excretion of protein, we studied 149 women referred to a day assessment unit for investigations for suspected preeclampsia. Paired samples were obtained for measurement of urinary protein:creatinine ratio and 24-h protein excretion. Collection of a 24-h urine sample was validated by the daily creatinine excretion. The outcome measure was proteinuria of 300 mg/day or more. Inaccurate 24-h collection was observed in 17% of women. All women (n = 56) with a protein:creatinine ratio >60 mg/mM had significant proteinuria. No woman with protein:creatinine ratio <18 mg/mM (n = 20) had significant proteinuria. We recommend that a dual cut-off should be used for excluding and "ruling in" the diagnosis of significant proteinuria. A 24-h urine collection should be used only for urinary protein:creatinine ratio values between 18 and 60 mg/mM in the detection of significant proteinuria.

Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy

OBJECTIVE

This guideline summarizes the quality of the evidence to date and provides a reasonable approach to the diagnosis, evaluation and treatment of the hypertensive disorders of pregnancy (HDP).

EVIDENCE

The literature reviewed included the previous Society of Obstetricians and Gynaecologists of Canada (SOGC) HDP guidelines from 2008 and their reference lists, and an update from 2006. Medline, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Registry of Controlled Trials (CCRCT) and Database of Abstracts and Reviews of Effects (DARE) were searched for literature published between January 2006 and March 2012. Articles were restricted to those published in French or English. Recommendations were evaluated using the criteria of the Canadian Task Force on Preventive Health Care and GRADE.

Comparison of 24-hour urinary protein and protein-to-creatinine ratio in women with preeclampsia

OBJECTIVE

To compare the spot urine protein-to-creatinine (P/C) ratio and 24-hour urine protein excretion in pregnant women with preeclampsia and also to determine the best discriminator values of the spot P/C ratios for 300 mg and 2000 mg protein per 24h.

STUDY DESIGN

Prospective study of 200 pregnant women with new onset hypertension at or greater than 140/90 mmHg after 20 weeks of gestation. Women were instructed to collect urine during a 24-hour period, and after the 24-hour urine sample collection was completed a mid-stream urine specimen was obtained for P/C ratio determination. The correlation between 24-hour urine protein excretion and spot urine P/C ratio was calculated. The receiver operating characteristic (ROC) curve was used to identify the cut-off values of the spot P/C ratios for 300 mg and 2000 mg protein per 24h. Areas under ROC curves were calculated.

RESULTS

There was a significant correlation between 24-hour protein excretion and the urine P/C ratio (r=0.828, p<0.0001). The cut-off P/C ratio for 300 mg per 24h was 0.28: sensitivity and specificity were 60.4% and 77.9%, respectively. The positive predictive value (PPV) was 77.5% and negative predictive value (NPV) was 60.9%. The cut-off P/C ratio for 2000 mg per 24h was 0.77: sensitivity and specificity were 96.8% and 98.6%, respectively. The PPV was 96.8% and NPV was 98.6%. Area under ROC curves for 24-hour urine total protein of 300-2000 mg/day and >2000 mg/day were 0.74 (95% CI 0.66-0.80) and 0.99 (95% CI 0.95-0.99), respectively.

CONCLUSIONS

Spot P/C ratio is a poor predictor of 24-hour proteinuria but can predict proteinuria >2000 mg better than 300-2000 mg.

Interpreting abnormal proteinuria in pregnancy: the need for a more pathophysiological approach

This review and opinion article focuses on the definitions and meanings of abnormal protein excretion in pregnancy, asking the following questions: Are our tests to determine abnormal proteinuria adequately performed? Are current guidelines for diagnosis of excessive proteinuria, especially when used to identify preeclampsia, supported by adequate data? Can the magnitude of proteinuria be used as a reliable clinical biomarker of the gravity of preeclampsia? Should timed urine collections, primarily 24-hour excretions, be supplanted by the urine protein/creatinine ratio in clinical practice? The answers to most of these questions are: We are not sure, or some guidelines are poorly supported by data and may prove erroneous. We suggest a more physiologic approach to assessment of proteinuria and believe that if clinicians and investigators looked at proteinuria in terms of how the kidney handles protein in health and disease it would lead to a more rational and evidence-based approach to proteinuria in pregnancy. Finally, we recommend that current cutoff for abnormal proteinuria be used to diagnose preeclampsia, but the level of proteinuria should not guide management. Other variables, such as status of blood pressure control, evidence of increasing organ damage in the liver and hematological systems, evidence of falling glomerular filtration rate, and signs of neurological involvement, are more reliable indicators of severity of preeclampsia.

Periodic urinary protein creatinine ratio for predicting significant proteinuria in preeclampsia in different alternatives: time effectiveness analysis

Preeclampsia is a big problem in obstetrics. The diagnosis relies mainly on the detection of both hypertension and proteinuria. The gold standard for the determination of proteinuria is 24 h urinary protein creatinine ratio; however, this approach is inconvenient and it is a considerable time consuming process that might bring a delayed diagnosis which might result in delayed treatment. Although spot urine measurement can be done, it has very poor prediction. The use of periodic urinary protein creatinine ratio is proposed as a possible alternative to solve this problem. Here, the author tries to perform a time effectiveness analysis for reported models on periodical urinary protein creatinine ratio for predicting significant proteinuria in preeclampsia. Data from previously published reports on this topic are used for further analysis. It seems that the alternative, 4 h, gives the most effectiveness in the shortest period of turnaround time. Hence, this alternative is recommended for screening proteinuria.

Protein/creatinine ratio in preeclampsia: a systematic review

OBJECTIVE

To estimate the accuracy of the protein/creatinine ratio in predicting 300 mg of protein in 24-hour urine collection in pregnant patients with suspected preeclampsia.

DATA SOURCES

Articles were identified through electronic databases (MEDLINE, CINHAL, and Cochrane) using the terms "preeclampsia," "protein/creatinine ratio," and "diagnosis," during the period January 1966 to October 2007. The relevant citations were hand searched.

METHODS OF STUDY SELECTION

Included studies evaluated patients for suspected preeclampsia with a 24-hour urine sample and a protein/creatinine ratio. Only English-language articles were included. Studies including patients with only chronic illness such as chronic hypertension, diabetes mellitus, or renal impairment were excluded. Using the Quality Assessment of Diagnostic Accuracy Studies questionnaire, we created group 1 satisfying all the required criteria and group 2 not satisfying all of it. Two researchers independently extracted the accuracy data. A graph comparing six receiver operating characteristic curves was plotted.

TABULATION, INTEGRATION, AND RESULTS

Twenty-one studies were identified, but only seven met our inclusion criteria (1,717 total patients). Group 1, with three studies, had 510 patients. The studies evaluated different cut points for positivity of protein/creatinine ratio from 130 mg/g to 700 mg/g. For protein/creatinine ratio 130-150 mg/g, sensitivity ranged from 90-99%, and specificity ranged from 33-65%; for protein/creatinine ratio 300 mg/g, sensitivity ranged from 81-98% and specificity ranged from 52-99%; for protein/creatinine ratio 600-700 mg/g, sensitivity ranged from 85-87%, and specificity ranged from 96-97%.

CONCLUSION

Random protein/creatinine ratio determinations are helpful primarily when they are below 130-150 mg/g, in that 300 mg or more proteinuria is unlikely below this threshold. Midrange protein/creatinine ratio (300 mg/g) has poor sensitivity and specificity, requiring a full 24-hour urine for accurate results. Higher thresholds have not been adequately studied.

Diagnostic accuracy of urinary spot protein:creatinine ratio for proteinuria in hypertensive pregnant women: systematic review

OBJECTIVE

To review the spot protein:creatinine ratio and albumin:creatinine ratio as diagnostic tests for significant proteinuria in hypertensive pregnant women.

DESIGN

Systematic review.

DATA SOURCES

Medline and Embase, the Cochrane Library, reference lists, and experts. Review methods Literature search (1980-2007) for articles of the spot protein:creatinine ratio or albumin:creatinine ratio in hypertensive pregnancy, with 24 hour proteinuria as the comparator.

RESULTS

13 studies concerned the spot protein:creatinine ratio (1214 women with primarily gestational hypertension). Nine studies reported sensitivity and specificity for eight cut-off points, median 24 mg/mmol (range 17-57 mg/mmol; 0.15-0.50 mg/mg). Laboratory assays were not well described. Diagnostic test characteristics were recalculated for a cut-off point of 30 mg/mmol. No significant heterogeneity in cut-off points was found between studies over a range of proteinuria. Pooled values gave a sensitivity of 83.6% (95% confidence interval 77.5% to 89.7%), specificity of 76.3% (72.6% to 80.0%), positive likelihood ratio of 3.53 (2.83 to 4.49), and negative likelihood ratio of 0.21 (0.13 to 0.31) (nine studies, 1003 women). Two studies of the spot albumin:creatinine ratio (225 women) found optimal cut-off points of 2 mg/mmol for proteinuria of 0.3 g/day or more and 27 mg/mmol for albuminuria.

CONCLUSION

The spot protein:creatinine ratio is a reasonable "rule-out" test for detecting proteinuria of 0.3 g/day or more in hypertensive pregnancy. Information on use of the albumin:creatinine ratio in these women is insufficient.

Protein:creatinine ratio in random urine samples is a reliable marker of increased 24-hour protein excretion in hospitalized women with hypertensive disorders of pregnancy

BACKGROUND

The protein:creatinine ratio in random, untimed urine samples correlates with 24-h protein excretion in pregnant women with and without hypertension. Nevertheless, whether this ratio is appropriate as a screening test for proteinuria is still unclear, in part because of the paucity of large studies.

METHODS

We measured protein:creatinine ratios in random urine samples and protein contents of 24-h urine samples in a cross-sectional study of 927 hospitalized pregnant women at >/=20-weeks of gestational age and in a 2nd cohort of 161 pregnant women. In the 2nd group, urine specimens were obtained before and after completion of the 24-h collections, avoiding 1st-morning void specimens.

RESULTS

Protein excretion was >/=300 mg/24 h in 282 patients (30.4%). The urine protein:creatinine ratio and the 24-h protein excretion were significantly correlated (r = 0.98, P <0.001). The protein:creatinine ratio as an indicator of protein excretion >/=300 mg/24 h was >/=0.3. The sensitivity and specificity were 98.2% and 98.8%, respectively. Positive and negative predictive values were 97.2% and 99.2%, respectively, and positive and negative likelihood ratios were 79.2 and 0.02, respectively. The diagnostic accuracy of the urinary protein:creatinine ratio was corroborated in the 2nd cohort of patients, which also showed no statistically significant difference in protein:creatinine ratio between samples obtained >24 h apart.

CONCLUSIONS

Random urinary protein:creatinine ratio is a reliable indicator of significant proteinuria (>300 mg/day) in nonambulatory pregnant women, irrespective of sampling time during the daytime. The protein:creatinine ratio may be reasonably used as an alternative to the 24-h urine collection method.