These guidelines contain advice on how to improve the appropriateness of laboratory test requesting. They aim to re-focus on the diagnostic process, emphasising clinical history, since 75% of diagnoses come from a good history. Clinical examination confirms the history; laboratory tests are used to confirm findings, aid prognosis, assist disease classification or, in some cases, make a diagnosis which cannot be determined other than by laboratory testing.
A subsidiary aim of these guidelines is to reduce unnecessary testing. Laboratory sample numbers rise at 5-15% per annum in many laboratories, driven in part by protocols and by the increasing number of laboratory users. It is thought that as much as 40% of test ordering in the acute hospital setting is inappropriate or non–contributory to clinical decision making The guidelines include advice where appropriate on frequency of re-testing.