Abstract: TH-PO660

Comparison of Different Urine Collection Techniques to Establish and Monitor Albuminuria in Healthy Toddlers

Session Information

  • Pediatric Nephrology
    November 02, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Developmental Biology and Inherited Kidney Diseases

  • 403 Pediatric Nephrology

Authors

  • Van den Belt, Sophie, UMC Groningen, Groningen, Netherlands
  • Gracchi, Valentina, UMC Groningen, Groningen, Netherlands
  • de Zeeuw, Dick, UMC Groningen, Groningen, Netherlands
  • Lambers Heerspink, Hiddo Jan, UMC Groningen, Groningen, Netherlands
Background

For measurement of albuminuria, guidelines in adults recommend to measure urinary albumin creatinine ratio (UACR) in first morning void (FMV) urine samples collected over three consecutive days. Since such a guideline is absent in toddlers, we compared several urine collection strategies.

Methods

Both a FMV and a random daytime urine sample were collected on three consecutive days at week 0 (visit 1), week 4 (visit 2) and week 8 (visit 3) in toddlers aged 12 to 48 months. Urinary albumin (UAC), urinary creatinine (UCR) and UACR were assessed. Intra-individual coefficients of variation (CV) of UAC and UACR were determined using only the first UAC or UACR measurement of each visit and using all three UAC or UACR measurements per visit, and were compared with published CV of adults (Witte et al. JASN 2009).

Results

80 toddlers (mean age 26.6 months, 53% male) were included. Geometric Mean (GM) UAC was 5.7 mg/L (SD 1.9) in FMV and 5.5 mg/L (SD 2.0) in random samples. GM UACR was 17.6 mg/g (SD 2.6) in FMV and 21.7 mg/g (SD 2.3) in random samples. The variation in GM UAC or UACR between toddlers derived from three FMV or random samples at visit 1 was smaller compared to single samples. The lowest intra-individual CV was observed when UAC was measured in FMV over three consecutive days (table). CV’s of UAC and UCR were similar to adults. However, UACR CV was considerably higher in toddlers.

Conclusion

These data confirm that FMV samples are preferred over random samples to establish and monitor (micro)albuminuria in toddlers, just like in adults. Surprisingly, unlike adults, within-individual CV was smaller for UAC compared to UACR in toddlers. This appears not to be explained by a higher UCR variability in toddlers. Further studies, particularly into variations in other renal functions that cause the mismatch between albumin and creatinine variation, are needed to explain these differences between children and adults.

Intra-individual CV, median (25th-75th percentile)
 ToddlersAdults (Witte et al. JASN 2009)
 Single urine sample per visitThree urine samples per visitThree urine samples
 FMV sampleRandom sampleFMV sampleRandom sampleFMV sampleRandom sample
UAC47.5% (20.4-99.8)*44.7% (11.8-85.6)38.3% (22.1-56.7)41.7% (24.4-64.1)30.9% (19.4-47.8)40.9% (27.8-70.2)
UACR54.3% (27.5-114.6)*†81.6% (39.5-144.3)*†44.5% (28.2-74.2)*61.7% (34.1-90.4)*†19.1% (11.6-28.4)*35.8% (17.6-55.6)
UCR42.3% (20.4-77.6)58.4% (35.6-87.7)27.8% (15.8-57.3)46.4% (23.9-69.5)23.5% (13.8-66.7)31.3% (19.1-56.1)

*p<0.05 vs UAC three FMV samples; †p<0.05 vs UACR three FMV samples