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

Abstract

Objective 1) To assess the correlation between urine albumin/ creatinine ratio (ACR) and 24-hour urine albumin excretion in women with pre-eclampsia, 2) to study the influence of potential confounders on this correlation and 3) to assess the variability of ACR between voids during a 24-hour period.Design Prospective study.Setting Fetal maternity ward, university hospital.Population Women with pre-eclampsia scheduled for quantitative albumin measurement with a 24-hour urine collection.Methods Random urine samples were obtained for analysis of ACRs during the time of 24-hour urine collections in 31 women. ACRs were also measured from the complete 24-hour collections. In five additional women, serial urine samples were obtained during the 24-hour collection.Main outcome measures Correlation between ACRs and albumin amount in 24-hour urine samples. Variability of the ACRs during a 24-hour collection.Results The random ACR was poorly correlated to 24-hour excretion of urine albumin (R 2 = 0.42). Adjustment for maternal age and nifedipine medication significantly (P = 0.044 and P = 0.023, respectively) improved the correlation (R 2 = 0.60). The mean variability (highest/lowest) of ACR during a 24-hour period was 222%. The ACR from the 24-hour collection had an excellent correlation to 24-hour excretion of urine albumin (R 2 = 0.96).Conclusions In women with pre-eclampsia, random ACR is not stable during the day and cannot predict 24-hour urine protein excretion accurately. ACR from the 24-hour collection is an accurate predictor of total albumin amount and can be used to minimise errors from incomplete collections.Keywords Albumin/creatinine ratio, pre-eclampsia, proteinuria, protein/creatinine ratio.Please cite this paper as: Wikström A, Wikström J, Larsson A, Olovsson M. Random albumin/creatinine ratio for quantification of proteinuria in manifest pre-eclampsia. BJOG 2006; 113:930-934.

Prediction of pre-eclampsia in early pregnancy by estimating the spot urinary albumin: creatinine ratio using high-performance liquid chromatography

“…19,31 Some but not all past studies have shown an excellent correlation between a spot urinary ACR and albumin excretion in a 24-hour urine sample in normal pregnancy and pre-eclampsia. [32][33][34][35][36] Many previous studies have measured microalbuminuria in an attempt to predict pre-eclampsia in early pregnancy, postulating that the stage of gross proteinuria is preceded by the stage of microalbuminuria. Using regression models, Bar et al 16 identified the presence of microalbuminuria at 28-30 weeks of gestation to be predictive of subsequent pre-eclampsia, with an odds ratio of 2.1 (95% CI 1.26-3.53).…”

RETIRED: Diagnosis, Evaluation, and Management of the Hypertensive Disorders of Pregnancy

“…ACR has published cut-offs of 2-8 mg/mmol for detection of 0.3 g/d proteinuria; it is not currently recommended [30,[38][39][40][41][42].…”

Assessment of Protein:Creatinine Ratio versus 24-Hour Urine Protein in the Diagnosis of Preeclampsia

“…However, on the other hand, over the last years, evidence has emerged undermining the usefulness of this test. In fact, consistency of this relationship has not been demonstrated in random urine samples on the same patient compared to 24-hour proteinuria [24], nor has it been possible to demonstrate that PCR in a single urine sample is useful to rule out proteinuria >300 mg per day [25]. The latter represents various conclusions resulting from the lack of homogeneity both in the units of measurement used as well as in the established cutoff values.…”

“…Moreover, an additional advantage is the fact that only a single urine sample is required; thus the method is more cost-efficient and provides speedy results [18,19]. However, in the pregnant population, PCR has shown dissimilar performances, and to date consensus regarding its real usefulness and cutoff values in the differential diagnosis of PHD has not yet been achieved [20,21,22,23,24,25,26,27,28,29]. …”