Cu isotopic analysis -can provide valuable hindsight when investigating Wilson’s disease (WD), but one of the problems related with this type of study is that usually low sample volumes are...
ObjectivesEndogenous antibodies (EA) may interfere with immunoassays, causing erroneous results for hormone analyses. As (in most cases) this interference arises from the assay format and most immunoassays, even from different manufacturers, are constructed in a similar way, it is possible for a single type of EA to interfere with different immunoassays. Here we describe the case of a patient whose serum sample contains EA that interfere several hormones tests. We also discuss the strategies deployed to detect interference.Subjects and methodsOver a period of four years, a 30-year-old man was subjected to a plethora of laboratory and imaging diagnostic procedures as a consequence of elevated hormone results, mainly of pituitary origin, which did not correlate with the overall clinical picture.ResultsOnce analytical interference was suspected, the best laboratory approaches to investigate it were sample reanalysis on an alternative platform and sample incubation with antibody blocking tubes. Construction of an in-house ‘nonsense’ sandwich assay was also a valuable strategy to confirm interference. In contrast, serial sample dilutions were of no value in our case, while polyethylene glycol (PEG) precipitation gave inconclusive results, probably due to the use of inappropriate PEG concentrations for several of the tests assayed.ConclusionsClinicians and laboratorians must be aware of the drawbacks of immunometric assays, and alert to the possibility of EA interference when results do not fit the clinical pattern.
We analysed the relationship between serum metal ions, radiological periprosthetic osteolysis and the clinical features in a series of 25 patients treated with fourth-generation metal-on-polyethylene total wrist prostheses. The mean implant follow-up was 7 years. Our results show that titanium was the main elevated serum metal ion in patients with the prostheses that we used; elevated serum cobalt or chromium values were infrequent. The risk of loosening was higher in an implant older than 6 years, with more than five periprosthetic osteolysis points according to our radiograph zone system, and serum titanium values between 26 to 31 µg/L. The presence of metallosis pseudotumours does not guarantee but increases the risk of implant failure, which may be asymptomatic or associated with little pain. Level of evidence: IV
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