December 18, 2008Journal of the American Society of Nephrology
First Morning Voids Are More Reliable Than Spot Urine Samples to Assess Microalbuminuria
Key result
First morning void urine samples yielded a microalbuminuria prevalence of 7.5%, closely matching the 10.0% prevalence from 24-hour collections, whereas spot urine samples overestimated it at 25.4% (P<0.001).
Why the study?
Does measurement of albuminuria in a first morning void provide a more reliable alternative to 24-h urine collection than a spot urine sample?
Population
241 participants of a prospective cohort study
Comparison
Measurement of urinary albumin concentration or… vs 24-h urine collection (gold standard)
Design
Cohort
Authors
Discussion
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Implication
First morning void may reduce microalbuminuria misclassification versus spot samples in practice; extends validation to observational cohorts.
Study Design
Type
Observational (n=241)
Multicenter
No
Structured PICO
Does measurement of albuminuria in a first morning void provide a more reliable alternative to 24-h urine collection than a spot urine sample?
P
Population
241 participants of a prospective cohort study
I
Intervention
Measurement of urinary albumin concentration (UAC) or albumin:creatinine ratio (ACR) in a first morning void or in a spot urine sample
C
Comparator
24-h urine collection (gold standard)
O
Outcome
Agreement with 24-h urinary albumin excretion (UAE) and prevalence of microalbuminuriasurrogate
Main Result
Absolute Event Rate: 7.5% vs 10%
p-value: p=0.18
Measurement of albuminuria in a first morning void, preferably as the albumin:creatinine ratio, is a more reliable alternative to 24-h urine collection than spot urine samples.
Limitations
- Conducted in a predominantly white cohort without diabetes or hypertension.
- Short follow-up time did not allow for evaluating which method best predicts renal and cardiovascular outcomes.
- Participants willing to collect 24-hour urine samples may be more compliant and less likely to make collection errors than the general population, potentially introducing bias.
Cite This Study
Witte et al. (2008) conducted an observational in Microalbuminuria (n=241). First morning void urine sample vs. 24-hour urine collection (gold standard) and spot urine sample was evaluated on Prevalence of microalbuminuria (p=0.18). First morning void urine samples yielded a microalbuminuria prevalence of 7.5%, closely matching the 10.0% prevalence from 24-hour collections, whereas spot urine samples overestimated it at 25.4% (P<0.001).