Amylase (AMS) is an enzyme that helps to digest the glycogen and
the starch. It is produced mainly by exocrine pancreas and salivary
glands. This determination is made mainly in diagnosis or to control
diseases of the pancreas as acute or chronic pancreatitis. It can also
reflect biliary or gastrointestinal disease and other upheavals2,5,6.
Clinical diagnosis should not be made on a single test result; it should
integrate clinical and other laboratory data.
PREPARATION
The reagent is ready to use.
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.
After opening, the reagent is stable for 60 days when properly capped
immediately after each opening and stored at 2-8ºC.
Signs of reagent deterioration:
- Presence of particles and turbidity.
- Blank absorbance (A) at 405 nm 0,40.
ADDITIONAL EQUIPMENT
- Spectrophotometer or colorimeter measuring at 405 nm.
- Thermostatic bath at 37ºC(Note 1).
- Matched cuvettes 1,0 cm light path.
- General laboratory equipment(Note 2).
SAMPLES
- Serum or plasma1
, remove from cells as soon as possible. It is
recommended to use heparin as anticoagulant.
- Urine, adjust pH to approximately 7,0 prior to storage.
Stability: 1 month at 2-8ºC.
PROCEDURE
1. Assay conditions:
Wavelength: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405 nm
Cuvette: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 cm light path
Constant temperature: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37ºC
2. Adjust the instrument to zero with distilled water.
3. Pipette into a cuvette:
4. Mix, incubate for 30 seconds.
5. Read initial absorbance (A) of the sample, start the stopwatch and
read absorbances at 1 minute intervals thereafter for 3 minutes.
6. Calculate the difference between absorbances and the average
absorbance differences per minute ( A/min).
CALCULATIONS
Serum or plasma A/min x 3954 = U/L AMS
Urine A/min x 7908 = U/L AMS
Units: One international unit (IU) is the amount of enzyme that transforms 1
mol of substrate per minute, in standard conditions. The concentration is
expressed in units per litre of sample (U/L).
Conversion factor: U/L x 0,01667 = kat/L.
QUALITY CONTROL
Control sera are recommended to monitor the performance of assay
procedures: SPINTROL H Normal and Pathologic (Ref. 1002120 and
1002210).
If control values are found outside the defined range, check the instrument,
reagents and technique for problems.
Each laboratory should establish its own Quality Control scheme and
corrective actions if controls do not meet the acceptable tolerances.
REFERENCE VALUES1
Serum or plasma Up to 90 U/L of -amylase
Urine Up to 450 U/L of -amylase
These values are for orientation purpose; each laboratory should establish its
own reference range.
PERFORMANCE CHARACTERISTICS
Measuring range: From detection limit of 0,2439 U/L to linearity limit of 2200
U/L.
If the results obtained were greater than linearity limit, dilute the sample 1/2
with NaCl 9 g/L and multiply the result by 2.
INTERFERENCES
Hemolysis interferes in the results1.
-Amylase activity can be inhibited by chelating agents like citrate and EDTA.
A list of drugs and other interfering substances with -amylase determination
has been reported by Young et. al3,4.
NOTES
1. -Amylase enzyme activity is temperature dependent. Assays
performed at temperatures 37ºC or 37ºC will show an apparent
decrease or increase levels.
2. Saliva and sweat contain -amylase. Avoid mouth pippeting and skin
contact with the reagent or material used.
3. Contains potassium thiocyanate. Avoid inhalation, skin or eyes contact.
If it happens, wash with plenty of water and consult a doctor.
4. SPINREACT has instruction sheets for several automatic
analyzers.
