Specimen Collection
A.
24h urine collection
with thymol preservative (preferred) OR no preservative (refrigerate during collection)
B.
Spot urine
(minimum 10 mL)
Sample stability:
Reference Intervals
Adults
|
|
24h urate output
(mmol/24h)
|
urate concentration
(mmol/L)
|
urate / creatinine ratio
(mmol/mmol)
|
|
Males
|
1.5 - 4.4
|
0.35 - 6.7
|
0.07 - 0.40
|
|
Females
|
1.5 - 4.4
|
0.24 - 5.5
|
0.06 - 0.50
|
Children
|
age
|
urate / creatinine ratio (mmol/mmol)
|
|
0 to 6 months
|
0.80 - 1.60
|
|
6 months - 1 y
|
0.70 - 1.50
|
|
1 - 2y
|
0.50 - 1.40
|
|
2 - 3y
|
0.47 - 1.30
|
|
3 - 5y
|
0.40 - 1.10
|
|
5 - 7y
|
0.30 - 0.80
|
|
7 - 10y
|
0.26 - 0.56
|
|
10 - 14y
|
0.20 - 0.44
|
|
14 - 17y
|
0.20 - 0.40
|
Uncertainty of measurement:
5%
References
:
1. Mayo Medical Laboratories Test calalog (
http://www.mayomedicallaboratories.com/test-catalog/
)
2. Matos, V., G. Van Melle, et al. (1999). "Urinary oxalate and urate to creatinine ratios in a healthy pediatric population."
Am J Kidney Dis
34
(2): e1.
Turnaround Time: Within 3 hours
Assay Method
Principle
: Enzymatic/ Colorimetric
Reagents:
Roche UA2 kit
Analyser:
Cobas c702
Diagnostic Use and Interpretation
Urate fractional excretion
is calculated by the formula:
FE-urate (%) = (urine urate / plasma urate) x (plasma creatinine / urine creatinine) x 100
where all concentrations are in mmol/L.
In healthy euvolemic subjects, FE-urate is approximately 10%. Contraction of extracellular fluid volume decreases FE-urate, and expansion of ECF volume increases it.
FE-urate greater than 12% strongly suggests SIADH, while a value less than 8% excludes SIADH.
Reference
Fenske, W., S. Stork, et al. (2008). "Value of fractional uric acid excretion in differential diagnosis of hyponatremic patients on diuretics."
J Clin Endocrinol Metab
93
(8): 2991-2997.
Contact Information
The chemical pathology team
can be reached via email:
chemicalpathologist@adhb.govt.nz
or via Lablink (09) 307 4949 ext 22000 or 09-3078995
Emails will receive priority attention from the on-call chemical pathologist. Include the patients NHI.
After-hours: contact
Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours
.