Urea is the final result of the metabolism of proteins; it is formed in the liver
from its destruction.
It can appear elevated urea in blood (uremia) in: diets with excess of
proteins, renal diseases, heart failure, gastrointestinal hemorrhage,
dehydration or renal obstruction1,4,5.
Clinical diagnosis should not be made on a single test result; it should
integrate clinical and other laboratory data.
STORAGE AND STABILITY
All the components of the kit are stable until the expiration date on the
label when stored tightly closed at 2-8ºC, protected from light and
contaminations prevented during their use.
Do not use reagents over the expiration date.
Signs of reagent deterioration:
- Presence of particles and turbidity.
- Blank absorbance (A) at 340 nm 1,00.
ADDITIONAL EQUIPMENT
- Spectrophotometer or colorimeter measuring at 340 nm.
- Matched cuvettes 1,0 cm light path.
- General laboratory equipment (Note 2).
SAMPLES
- Serum or heparinized plasma1
: Do not use ammonium salts or
fluoride as anticoagulants.
- Urine1
: Dilute sample 1/50 with distilled water. Mix. Multiply results
by 50 (dilution factor); Preserve urine samples at pH 4.
Urea is stable at 2-8ºC for 5 days.
NOTES
1. UREA CAL: Proceed carefully with this product because due its nature
it can get contaminated easily.
2. Glassware and distilled water must be free of ammonia and
ammonium salts1
.
3. Calibration with the aqueous standard may cause a systematic error in
automatic procedures. In these cases, it is recommended to use a
serum Calibrator.
4. Use clean disposable pipette tips for its dispensation.
5. SPINREACT has instruction sheets for several automatic
analyzers. Instructions for many of them are available on request.
BIBLIOGRAPHY
1. Kaplan A. Urea. Kaplan A et al. Clin Chem The C.V. Mosby Co. St
Louis. Toronto. Princeton 1984; 1257-1260 and 437and 418.
2. Young DS. Effects of drugs on Clinical Lab. Tests, 4th ed AACC Press,
1995.
3. Young DS. Effects of disease on Clinical Lab. Tests, 4th ed AACC
2001.
4. Burtis A et al. Tietz Textbook of Clinical Chemistry, 3rd ed AACC 1999.
5. Tietz N W et al. Clinical Guide to Laboratory Tests, 3rd ed AACC 1995.
