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Summary Background The presumed cause of congenital thrombophilia can now be explained in ~50% of familial thrombosis cases following evaluation of a range of markers, primarily comprising factor V Leiden (FVL), activated protein C resistance (APCR), protein C (PC), protein S (PS) and antithrombin (AT). However, the effectiveness of such evaluations is largely determined by limiting improper investigations, either in inappropriate patients or at unsuitable timepoints. Aim To evaluate clinical ordering patterns for a range of thrombophilia associated tests at a tertiary level public facility. Methods Several independent audits into clinical requests for FVL, APCR, PC, PS, and AT testing were performed at our institution. Results We identified a wide variety of clinical ordering background, although most requests related to ‘thrombosis’ or ‘obstetric’ indications. For FVL, the detection rate of heterozygotes continues to decline and is currently ~10% of investigations. For APCR, review of clinical requests and clinical notes indicated that around 36% of investigations occurred whilst patients were on anticoagulant therapy. For PC, PS and AT investigations, additional testing of samples that yielded low test results for PC, PS and/or AT indicated that an alarming 80% of these cases likely derived from patients on anticoagulant therapy. Conclusion These results continue to reflect on poor patient or timing selection for congenital thrombophilia investigations that compromises the utility of these tests. In total, this would yield a very high rate of false positive identification for disorders that patients do not have, raising the question: are broadly based congenital thrombophilia investigations doing more harm than good?

The sera of 30 patients with complement-fixing antibodies to Mycoplasma pneumoniae (titres larger than or equal to 32) were treated with staphylococcal protein A. This procedure effectively removed 90 to 95% of the IgG antibodies. The Mycoplasma-specific antibodies in the treated sera could then be measured by a complement fixation test. This provides a useful test for distinguishing serological responses to recent Mycoplasma pneumoniae infections from anamnestic responses due to past exposure to Mycoplasma pneumoniae.

In spite of the recent development of many rapid methods of diagnosing viral and mycoplasmal disease, serology still remains an important diagnostic tool, being the only method readily available in many laboratories. The serological response to most viral and mycoplasmal infections is such that at least a few days must elapse before it can be detected even by the most sensitive tests presently available. The complement fixation test, though one of the oldest and least sensitive serological tests developed, is still widely used. Hacmagglutination inhibition tests are applicable to infections caused by the haemagglutinating viruses. Passive agglutination of antigen coated particles can be used for the non-haemagglutinaling agents. More recently techniques using labelled immunological reactants such as radio-immunoassays, ELISA and fluorescent antibody assays have been used. These techniques, because of their adaptability to automation, will probably replace the older methods. The persistence of antibodies developed during infections in the remote past and anamnestic responses necessitate the collection of paired specimens to make any useful interpretation of results. This tends to discourage clinicians from using serological tests for diagnosis. However, the development of techniques to detect specific antibody in the IgM fraction of sera has made possible the diagnosis of recent infections with a single specimen of serum.