Cancer Diagnosis Program | Biorepositories and Biospecimen Research Branch

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First morning voids are more reliable than spot urine samples to assess microalbuminuria.

Author(s): Witte EC, Lambers Heerspink HJ, de Zeeuw D, Bakker SJ, de Jong PE, Gansevoort R

Publication: J Am Soc Nephrol, 2009, Vol. 20, Page 436-43

PubMed ID: 19092125 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study investigated if first-morning or subsequently voided urine was representative of the measurement of albumin and the ACR in 24 h urine. Patients were participants in the Prevention of Renal and Vascular End-stage disease (PREVEND) study and, if on hypertensive medicine, were on a stable dosage. At three times separated by 3 weeks, 241 participants collected a 24 h urine specimen (10 PM-10 PM), a first-morning mid-stream void following the 24 h collection, and a subsequent void at the clinic. Urine was refrigerated for 48 h or less before measurement of albumin and creatinine using a Behring BN II analyzer.

   Summary of Findings:

   Although the median urinary albumin concentration (UAC) and ACR in first-morning urine were lower than in 24-h urine (6.1 mg/L versus 6.5 mg/L, P=0.013 and 5.7 versus 8.3, P<0.001, respectively), the median UAC and ACR of subsequently collected spot urine were higher than in 24-h urine (11.5 versus 6.5 mg/L, P<0.001 and 10.5 versus 8.3, P<0.001).  UAC and ACR were strongly correlated between 24-h urine and first-morning urine (r=0.85 and r=0.87, respectively) and spot urine specimens (r=0.71 and r=0.73, respectively). Importantly, use of first-morning void rather than subsequent spot urine resulted in a higher percentage of albumin measurements within 30% of that in the 24-h urine and a reduced bias. Similarly, the percentage of first-morning urine specimens considered to have microalbuminuria by UAC and ACR were not significantly different from that in 24 h urine, but the percentage of microalbuminuric specimens was significantly higher (25.4% based on UAC and 24.5% based on ACR, versus 10% in 24 h urine, P<0.001, both) when spot urine was used. Intraindividual variation was lowest in 24-h urine followed by first-morning urine and was lower for ACR than UAC but was not substantially impacted by patient gender. Using gender-specific cut-offs, microalbuminuria results agreed with those in 24-h urine in 81.8% of first-morning specimens and 72.1% of subsequent void specimens.

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • Other Preservative

   Diagnoses:

   • Not specified

   Platform:

   Analyte	Technology Platform
   Protein	Clinical chemistry/auto analyzer
   Small molecule	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Time of biospecimen collection	10 PM-10 PM First morning Subsequent void
   Biospecimen Acquisition	Method of fluid acquisition	Voided urine (24-h collection) Voided urine (spot collection)

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