Assessing urinary albumin excretion in pre-eclamptic women: which sample to use? Helle Kieler a,b, * , Tuttan Zettergren a , Hanna Svensson b , Paul W. Dickman b , Anders Larsson c Objective To evaluate whether the gold standard of 24-hour urine collection for measuring albumin excretion in pre-eclamptic women could be substituted by shorter collection periods. Design Prospective study. Setting Fetal maternity ward, university hospital. Participants Thirty women with pre-eclampsia and a positive urinary test strip for protein of at least 2þ. Methods From each woman, within a 25-hour period, three spot, two 12-hour (day and night) and one 24-hour urine sample were collected. Urine albumin concentrations in milligrammes per litre were analysed by rate nephelometry on a Beckman Array protein system. The urinary albumin concentrations in the spot and the 12-hour samples were compared with the concentration in the 24-hour urine collection. Main outcome measures Urinary albumin concentrations in spot and 12-hour samples measured against the standard 24-hour albumin excretion. Results Albumin concentrations in the day and night collection fitted closely with the concentrations of the 24-hour collection. The median difference between the 24-hour and the day collection was 3 mg/L (interquartile range 264 to 116 mg/L). The median difference between the 24-hour and the night collection was 17 mg/L (interquartile range 186 to 210 mg/L). The association of urinary albumin concentration in the 24-hour collection and the spot samples was much weaker. Of the spot urine samples, the albumin concentration in the sample taken on the morning after admission to hospital was closest to the 24-hour urinary albumin excretion, with a median difference of 62 mg/L (interquartile range 1131 to 285 mg/L). Conclusion The gold standard of 24-hour urinary excretion for assessment of albuminuria in pre-eclamptic women can be substituted with a 12-hour collection. Spot urine samples were inaccurate and are therefore not recommended for quantification of albumin excretion. INTRODUCTION Albuminuria is an important sign of pre-eclampsia and repeated urine analyses to screen for albuminuria are part of standard antenatal care. These urine analyses are per- formed on random spot urine specimens using a test strip assay, being a procedure that is acceptable to most pregnant women. However, if a test strip is positive for protein 2þ or more in the absence of bacteriuria, the next step is usually a 24-hour urine collection for quantification of albumin. The 24-hour urine collection is inconvenient for the woman, costly and may also be inaccurate due to incomplete collection. When pre-eclampsia with persistent albuminuria devel- ops, urinary albumin excretion is monitored by frequent 24-hour urine samples. The purpose of this tedious surveil- lance is that increased albumin excretion is a sign of aggra- vation of pre-eclampsia and reflects serious nephropathy. Massive albumin excretion may result in planned preterm delivery. Collection of urine for determining albumin excretion has been studied in diabetic patients 1–5 . In the Saint Vincent declaration on diabetic nephropathy 6 , the 24-hour urine collection is recommended as the standard when screening for microalbuminuria. If urine collection is not possible, a morning urine sample can be used, or, as a third option, a semiquantitative test strip. These recommenda- tions are based on the circadian rhythm in urinary albumin excretion 7 . However, for pregnant women, particularly if in hospital, the circadian variation in albumin excretion is smaller or absent 8 , and it may therefore be possible to use shorter collection periods. The aim of this study was to evaluate whether a 24-hour urine collection for measuring urinary albumin excretion in BJOG: an International Journal of Obstetrics and Gynaecology January 2003, Vol. 110, pp. 12–17 D RCOG 2003 BJOG: an International Journal of Obstetrics and Gynaecology PII:S1470-0328(02)01440-4 www.bjog-elsevier.com a Department of Women’s and Children’s Health, Obstetrics and Gynaecology, Uppsala University Hospital, Sweden b Department of Medical Epidemiology, Karolinska Institutet, Stockholm, Sweden c Department of Medical Sciences, Uppsala University Hospital, Sweden * Correspondence: Dr H. Kieler, Department of Medical Epidemiology, Karolinska Institutet, PO Box 281, SE-171 77 Stockholm, Sweden.