Erroneous laboratory results: what clinicians need to know.

Laboratory tests such as 'conventional biochemistry' are analytically robust and trusted, however, some common tests performed by immunoassays, eg thyroid function tests, are inherently more prone to analytical interference, giving rise to incorrect results. Interfering antibodies capable of causing potentially misleading results in immunoassay varied from about 0.4% to 4%. Furthermore, this form of interference cannot be predicted a priori and cannot be detected even by most stringent laboratory quality control assurance schemes because it is unique to an individual sample. Since more than 10 million immunoassay tests are carried out yearly in the UK alone, the impact of this problem on delivering appropriate patient care can no longer be ignored. Clinicians tend to perceive all laboratory data in the same light. Because of this, increased awareness of the inherent limitations of these laboratory tests should trigger a more measured and thoughtful approach, thus ensuring patients receive appropriate investigations and treatment.