Blood- plasma- and serum samples
The first step in the process of examination of a sample are the pre-analytics.
Pre-analytics include all steps from preparing the patient, taking the sample and shipping it to the laboratory to the
sample preparation for analysis.
Preparation of the patient
Before taking of the blood sample the patient should have been fasting for about 10-12 hours. Otherwise incorrect
results are to be expected in particular for cholesterol, glucose and TLI. In addition parameters such as alpha-amylase,
ALT, AST, bilirubin, total protein, triglycerides, serum bile acids, leukocytes and calcium can be affected.
It is advisable to inform the animal owner about the influence of physical activity on the results of a blood examination.
Especially muscular enzymes such as CK, LDH and AST can show increased levels in the serum following physical
exertion. In addition, glucose and lactat can show elevated serum levels.
- animal- or owner name should be recorded clearly on the lab order sheet and the sample tube.
- for functional tests the times when samples were taken must also be recorded
Sample material ?
Details about the recommended sample material (blood, serum, plasma) for the requested tests can be taken from
our summary of diagnostic tests or the lab order form.
- For the blood profile EDTA-blood is the most appropriate sample material
- for clinical-chemical and/or serological parameters EDTA-plasma should be used only as an exception
because EDTA does interfere with the analysis of certain parameters.
- serum samples are drawn into collection tubes without clotting inhibitors
- allow 30 - 60 min. for the clot to form
- separate the clot from the sides of the collection tube
- centrifuge at 3000 rpm for 10 min
- remove serum and transfer to a clean, uncoated tube
- plasma samples are drawn into tubes coated with anticoagulants (heparin, EDTA, citrate)
- Attention: the additives limit the number of test parameters!
- can be centrifuged immediately after collection (10 min, 3000 rpm)
- The submission of whole blood samples should be the exception (very small amount of sample, blood profile
see above) in order to minimize artefacts caused by haemolysis (see below) due to damage of the erythrocyte
Factors causing interference with the analysis
Haemolysis is caused by leakage of intracellular components of the erythrocytes due to damage of the cell membrane,
specifically iron, potassium and haemoglobin. Haemoglobin causes a red coloration of serum/plasma and interferes
with the photometric testing of clinical-chemical parameters.
Presence of excess lipids in the blood result in a turbid, milky coloration of the serum/plasma mostly caused by stress
or non-fasting patients.
Icterus is characterized by a yellowish coloration of serum/plasma due to an excess of bilirubin, caused by a medical
condition. Photometric evaluation in the 400-500nm range may be influenced.
|Haemolysis ||LDH, CK, AST, bilirubin, AP, creatinine,|
glucose, Ca, PO4, K, Mg, Fe, fructosamine, haemoglobin
|Lipemia ||ALT, AST, AP, bilirubin, glucose, Ca, PO4,|
total protein, lipides, hemoglobin
|albumin, amylase, Na, Cl, K, PO4|
|Icterus ||AP, total protein, Cl, PO4|
|triglycerides, creatinine, Mg |
|Penicillin G ||K |
|Tetracykline ||K , PO4 |
|Salicylate ||K |
|Corticosteroides ||CK , AP , glucose , K , Ca , Na , total protein |
|Phenylbutazon ||Ca , Na |
|Barbiturates ||CK |
|Halothan-anaestesia||CK , PO4 |
|glucose infusion ||glucose , PO4 |
- EDTA or Lithium-Heparin-blood
- when drawing the sample discard the first 0.5 ml of blood because they contain an increased amount
of coagulation factors.
- let blood run slowly down the side of the sample tube
- observe correct draw volume!
- after drawing the sample the tube must be inverted gently several times.
- if coagulopathy is suspected prepare a blood smear for the differential blood profile
- for shipping samples must be protected from freezing in the winter and heat in the summer.
glucose and lactat
sodium fluorid or sodium oxalate tubes required for testing
- Na-citrate-plasma ist required, observe correct draw volume; ratio 1:10 (blood-citrate)
- the sample should be spun down in the practice
- the tube must be filled exactly up to the mark on the tube
polymerase chain reaction (PCR)
- submit swabs without transport media!
- sampling with the cyto brush yields a higher number of cells for analysis,
required when testing genetic diseases
- EDTA-samples must not be older than 24 hours!
- days of testing: Wednesdays and Fridays