Page 358 - The Veterinary Laboratory and Field Manual 3rd Edition

Clinical chemistry 327

ting animal health professional should identify (in temperate climates) or left in the refrigera-
which tests are needed to confirm the suspected tor or cold room to clot. Refrigeration helps to
diagnosis and should contact the laboratory contract the clot; the following day the serum
in advance to check the sample requirements, can be removed carefully using a pipette and
that is, before the samples are collected. Blood stored in labelled serum vials. Note that plas-
samples should be handled carefully to prevent tic syringes are not suitable for the collection
haemolysis. A delay in centrifugation or poor of samples for some tests and that plastic tubes
collection technique may result in a poor-qual- may promote haemolysis of whole blood during
ity sample and false results due to transfer of the clotting process. A summary of the recom-
ions across the red blood cell membranes and mended collection and dispatch requirements
leakage into plasma or serum. Heparinized (and for some standard biochemical tests on blood
fluoride/oxalate) samples may be spun down samples is provided in Table 7.1. If haemolysis
(4000 rpm for 2–3 min or 2500 rpm for 10 min) occurs during sample collection, or while sepa-
and the plasma separated directly. Whole blood rating the serum/plasma, the test(s) may give
samples should be collected in glass containers invalid results and will need to be repeated.
and left to stand overnight at room temperature

Table 7.1 Summary chart for blood sample collection and recommendations for
specific biochemical tests.

Tests/indications Specimens Container* Stability and comments**
ALT (alanine amino 3–5 ml clotted Dry glass container, Haemolysis interferes with the
transferase)/enzyme blood (serum) i.e. red topped test. Stable in blood at 4°C for
released in tissue vacutainer 12 h and in serum for up to 36 h
damage
AST (aspartamine 3–5 ml clotted Dry glass container, Haemolysis interferes with the
animotransferase)/ blood (serum) i.e. red topped test. Stable in blood at 4°C for
enzyme released in vacutainer 12 h and in serum for up to 36 h
tissue damage
Albumin/protein levels 2–3 ml clotted Dry glass container, Stable in blood at 4°C for 8 h and
low in liver damage and blood (1 ml i.e. red topped in serum for 4 days
starvation serum) vacutainer
Protein/usually 3–5 ml clotted Dry glass container, Stable in blood at 4°C for 8 h and
determine fractions blood (serum) i.e. red topped in serum for 4 days
using electrophoresis vacutainer
Amylase/elevated 3–5 ml clotted Dry glass container, Poor stability in whole blood, stable
levels in pancreatic and blood (serum) i.e. red topped in serum sample for up to 12 h at
neoplastic disease vacutainer 4°C. Can store longer if frozen
Bilirubin/elevated 3–5 ml clotted Dry glass container, Protect sample from light, table in
levels in obstructive blood or 3 ml with i.e. plain red topped whole blood at 4°C for 12 h and
liver disease and some anticoagulant vacutainer or with in serum for 48 h
haemolytic conditions (serum or plasma) EDTA (purple topped)
Creatinine and urea/ 5–7 ml clotted Dry glass container, Stable in whole blood at 4°C for
elevated levels in blood (serum) i.e. vacutainer 8 h and in serum for 4 days
some renal diseases,
dehydration

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