Biosystems Urea Reagent
Reagent for the measurement of urea concentration in human serum, plasma or urine. The
obtained values are useful as an aid in the diagnosis and treatment of chronic renal failure, and to
evaluate the function of renal glomerulus.
This reagent is for use in the BioSystems BA analyzers or in other analyzer with similar
Urea is synthesized in the liver as a by-product of the deamination of amino acids. Its elimination
in the urine represents the major route for nitrogen excretion.
Elevated urea concentration in plasma is found as a result of a high-protein diet, increased
protein catabolism, after a gastrointestinal hemorrhage, mild dehydration, shock and heart failure
or treatment with glucocorticoids (pre-renal uremia)1,2
Post-renal uremia is caused by conditions that obstruct urine outflow: nephrolithiasis, tumor or
prostatic hypertrophy. The usefulness of urea as an indicator of renal function is limited by the
variability of its plasma concentration as a result of nonrenal factors1,2
Clinical diagnosis should not be made on the findings of a single test result, but should integrate
both clinical and laboratory data.
PRINCIPLE OF THE METHOD
Urea in the sample consumes, by means of the coupled reactions described below, NADH that
can be measured by spectrophotometry3,4
A. Reagent: Tris 100 mmol/L, 2-oxoglutarate 5.6 mmol/L, urease 140 U/mL, glutamate
dehydrogenase 140 U/mL, ethyleneglicol 220 g/L, sodium azide 0.95, pH 8.0.
B. Reagent: NADH 1.5 mmol/L, sodium azide 9.5 g/L.
WARNING: H302: Harmful if swallowed. EUH031: Contact with acids liberates toxic gas.
P301+P312: IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel
unwell. P330: Rinse mouth.
For further warnings and precautions, see the product safety data sheet (SDS).
STORAGE AND STABILITY
Store at 2-8 ºC.
Components are stable once opened until the expiry date marked in the label if they are stored
well closed and care is taken to prevent contamination during their use.
On board stability: Reagents open and kept in the refrigerated compartment of the analyzer are
stable 30 days.
Indications of deterioration: Absorbance of the blank below the limit indicated in “Test
ADDITIONAL MATERIALS REQUIRED (NOT PROVIDED)
Biochemistry Calibrator (BioSystems cod. 18011) or Biochemistry Calibrator Human (BioSystems
Reagents are provided ready to use.
Serum, plasma or urine collected by standard procedures.
Urea in serum or plasma is stable for 7 days at 2-8ºC. Heparin is recommended as
Urea in urine is stable for 2 days at room temperature if microbial growth is prevented5
A reagent blank should be done every day and a calibration at least every 30 days, after reagent
lot change or as required by quality control procedures.
It is recommended to use the Biochemistry Control Serum level I (cod. 18005, cod. 18009 and
cod. 18042) and II (cod. 18007, cod. 18010 and 18043) and the Biochemistry Control Urine (cod.
18054 and cod. 18066) to verify the accuracy of the measurement procedure.
Each laboratory should establish its own internal Quality Control scheme and procedures for
corrective action if control results are not within the acceptable limits.