Using this Guide

The lists of causes of abnormalities for each analyte are not exhaustive and should be used as checklists. The more common abnormalities are indicated in bold print. For comprehensive lists and in depth discussion you are referred to the references at the end of this section. Those references in bold print have been consulted extensively to produce this guide and are considered essential reference material.

Sampling

The type of sample preferred for each analyte is indicated in the current price list. Serum or heparin plasma should be separated as soon as possible after sample collection (allowing for clotting) to minimise haemolysis. Where there is a choice of serum or heparin plasma serum is always the preferred sample. The use of serum gel tubes will simplify the submission of serum samples.
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Reference Ranges

Reference ranges are printed on all reports against each analyte. These may be extracted from the literature but are validated in-house and are subject to periodic revision, particularly if the test methodology is changed.
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Flagging Ranges

Reports include results that are highlighted and printed in bold. This feature is triggered by the flagging range set for each individual analyte. This range may not be the same as the reference range. Some analytes, AP for example, are very dynamic and small variations from the reference range may not be of clinical significance. In this case the flagging range will be higher than the upper limit of the reference range. Other analytes, calcium for example, are much less dynamic.; even very small variations from the reference range may be of marked clinical significance and the flagging range will be the same as or even within the reference range. Flagging ranges are intended to be a guide to the degree of abnormality of an analyte and should be interpreted accordingly.
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Haemolysis, Lipaemia and Icterus

Haemolysis, lipaemia and icterus in a serum or plasma sample may lead to false elevations (or reductions) in the measured concentrations of biochemical analytes. The presence of haemolysis or lipaemia is indicated on the report and affected analytes are flagged. Usually there is a false elevation in measured concentration, the exceptions include glucose (reduced due to haemolysis), calcium (reduced due to gross haemolysis) and creatinine (occasionally reduced due to haemolysis). Further advice on the interpretation of haemolysed, lipaemic or icteric samples may be obtained from the laboratory.
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Drug Therapy

Drugs may influence the measured concentration of biochemical analytes through their biological actions. Occasionally drugs will interfere directly with the analytical chemistry. It is essential that details of any drug therapy are included in the history on the submission form. Advice on the influence of drugs and the interpretation of results may be obtained from the laboratory.
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Sampling

This guide indicates the preferred sample for each analyte. It should be noted that where combinations of analytes are requested, as in profiles, the preferred sample for the combination is indicated in the current price list. Inappropriate or poor quality samples may affect the accuracy of the test or may mean that the test cannot be carried out. Unless otherwise indicated the serum or plasma for biochemistry should be separated from the clot or cells as soon as possible after the sample is taken and before despatch to the laboratory. If you have a centrifuge the simplest procedure is to use gel tubes. To use these allow the sample to clot and separate then centrifuge tubes the gel material forms an interface between the clot and the serum. The tube can then be posted without the serum having to be removed.
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