At first, these assays were called sensitive TSH assays to distinguish them from existing methods.
The second- and third-generation TSH assays, however, are not without flaws.
Although some experts recommend the exclusive use of third-generation TSH assays, financial considerations are a strong argument for routine use of second-generation assays, which are adequate for most clinical applications.
The National Academy of Clinical Biochemistry has recommended that the functional sensitivity of TSH assays be [less than or equal to]0.
Our results indicated that all third-generation TSH assays had functional sensitivities <0.
An alternative approach that might be useful to address the ability of TSH assays to measure low TSH concentrations is to estimate the minimum detectable concentration (11).
In conclusion, interference from heterophilic antibodies in TSH assays
has become exceptional but still exists (14-16).
Free hormone levels are less reliable measures of thyroid function than are TSH assays because they are more susceptible to factors that can adversely affect test accuracy.
These isoforms may have increased or decreased biological activity but may react unpredictably with TSH assays.
The test for thyrotropin-releasing hormone (TRH) has been almost completely replaced by more preferred immunoradiometric and other supersensitive TSH assays
Persistent problems with the specificity of immunometric TSH assays
07), and as already reported with the Immulite and AxSYM TSH assays
(5), a negative bias between the Vitros ECI TSH results and the Elecsys, Immulite, and ADVIA Centaur TSH results was observed at low values <0.