Discordant or apparently anomalous results
On occasions, there appears to be a dissonance between the clinical findings and the laboratory results. In these circumstances, a distinction needs to be made between a previously unsuspected diagnosis, subclinical disease and anomalous assay results. If there is any doubt, the laboratory should be contacted as analytical interference does not improve with repeated testing!
The following steps may be helpful in evaluating anomalous assay results:
- Re-evaluation of the clinical context, with particular attention to the anticipated features and the medication history.
- The laboratory should be able to repeat the analysis (if necessary) or to arrange analysis by another method/technique.
- Follow-up to establish whether the abnormality is transient or persistent.
- Evaluation of the patient and family members for evidence of inherited disorders.
In some circumstances, the cause of an apparently anomalous or unusual laboratory result becomes clear from the clinical context. By taking into account the effects of drug therapy and general health issues, confidence in assay validity can be affirmed thereby avoiding unnecessary further investigation. Without the relevant information, even an alert laboratorian is unable to consider a possible assay anomaly or error.
Ismail AAA, J.H.Barth JH, Walker PL, Cawood M. Interference in immunoassay is an underestimated problem. Ann Clin Biochem 2002;39:366-373
Ismail AAA, Walker PL, Barth JH,Lewandowski KC, Jones RG, Burr WA. Wrong biochemistry results: two case reports and observational study in 5310 patients on potentially misleading thyroid-stimulating hormone and gonadotropin immunoassay results. Clin Chem 2002;48:2023-2029
Ismail AAA, Walker PL, Fahie-Wilson MN, Jassam N, Barth JH. Prolactin and macroprolactin: a case report of hyperprolactinaemia highlighting the interpretation of discrepant results. Ann Clin Biochem 2003;40:298-300
JHB 21 July 2008