Biochemistry
Introduction
NSW Department of Primary Industries' laboratories do not carry out any biochemical analysis; all such testing is outsourced to laboratories that are accredited by NATA to conduct biochemical tests.
In some cases it is more appropriate to apply a test on fresh samples in the field rather than submit samples to a laboratory, e.g. urine analysis, where commercially available kits will provide a more reliable answer on the spot, rather than the same test applied in the laboratory 24 to 48 hours later.
Standard Containers and Equipment
Contamination of glassware and other collection equipment by traces of the element of interest has been an issue in the past. Vacuum blood tubes and needles, and disposable plastic containers have eliminated this problem.
Blood vacuum tubes, silicone coated
For serum samples.
Blood vacuum tubes with heparin or EDTA
For whole unclotted blood for glutathione peroxidase testing. Also for plasma samples.
Serum vials (5 ml screw-top plastic containers)
For serum and fluid samples.
Sterile plastic containers
For tissues, organs etc.
Collection of Specimens
Blood and serum samples
Blood samples should be collected aseptically into the appropriate 10 ml vacuum tube.
Contamination of the sample by soil, faeces, hair, etc., must be avoided.
Where whole blood will not arrive at the laboratory within 24 hours of collection, serum should be separated from the clot as soon as possible and frozen or chilled in 5 ml serum vials. Chilling should also continue in transit.
Care should be taken to avoid haemolysis (see Serology - Avoiding Haemolysis of Samples). Haemolysis will seriously interfere with the level of serum magnesium, phosphate, total protein, albumin and enzyme levels.
Sera for Vitamin A or E analysis must be protected from heat and light. Separated sera or plasma must be placed into 5 ml containers wrapped in foil, then forwarded chilled to the laboratory.
Plasma samples
At least 2 ml of plasma should be submitted frozen in 5 ml screw-capped containers.
The blood sample should be collected in the appropriate blood vacuum tube. Where whole blood will not arrive at the laboratory within 24 hours of collection, plasma should be separated by centrifugation as soon as possible and preferably within 4 hours of collection. The plasma should be removed, free of all cells and then kept chilled or frozen. Chilling should also continue in transit.
Plasma for Vitamin A or E analysis must be protected from heat and light. Separated serum or plasma must be placed into 5 ml containers wrapped in foil, then forwarded chilled to the laboratory.
Tissue samples
At least 50 g of tissue should be submitted frozen in a screw capped container. Care must be taken to avoid contamination by soil, faeces, ruminal or intestinal contents when collecting tissue for biochemical analysis.
Different organs must be submitted in separate containers. If other examinations are required, e.g. bacteriology, pathology, then duplicate samples as required for the other examinations should be submitted in separate containers.
Tissues for vitamin A or E analysis
These should be protected from heat and light; wrap in foil and submit frozen to the laboratory.
Storage and Despatch of Specimens
Samples of tissues must be frozen until despatch.
Specimens should be forwarded in an insulated container with an icebrick. To prevent frozen samples from becoming heated during transit, always ensure there are several ice bricks to ensure samples arrive frozen:
Always seal the Specimen Submission Form in a separate plastic bag.
Guide to interpretation of biochemical parameters in sheep and cattle
Normal values are supplied by the laboratories to which we outsource and are included in our reports to submitters. Suggested normal values for some analytes are included under specific diseases in the section 'Specimens (by disease or syndrome)' of this manual. Where values supplied by laboratories differ from these suggested values, the former should be used.
The Serum enzymology section includes information on enzyme changes see in various conditions.
Refer to relevant section of the manual. See:
- Acetonaemia (Ketosis)
- Copper deficiency
- Hypomagnesaemia (Grass tetany, lactation tetany and milk tetany of calves)
- Hypocalcaemia
- Hypophosphataemia
- Muscular degeneration, nutritional (Selenium deficiency)
- Serum enzymology
- Vitamin A and E
- Vitamin B12