Analytical and clinical assessment of a commercial kit for the simultaneous determination of free thyroxine and thyrotropin.
The SimulTRAC FT4/TSH kit (Becton Dickinson), allowing a simultaneous determination of free thyroxine (FT4) and thyrotropin (TSH), was assessed in terms of analytical quality and clinical performance. The results of a multicenter trial were included in this study to obtain a more complete and reliable information. The current validation procedures (ie evaluation of analytical imprecision and sensitivity, between-kit comparison of estimates and--limited to TSH--check of response linearity on dilution) demonstrated quite acceptable analytical characteristics for both the FT4 and the TSH tests. The diagnostic sensitivity and predictive value were derived for separate and combined tests from a relatively large number of cases (ie 401 euthyroids, 127 overt and 48 subclinical hypothyroids, 205 overt and 80 compensated hyperthyroids). The TSH test proved more effective than FT4 in discriminating both overt and subclinical dysfunctions, and, in this respect, the test association was found to add a little advantage--if any. However, the extension of the concepts of diagnostic efficiency to any combination of test results--favoured by their production in a single assay--provides a basis to establish diagnostic protocols and to predict costs and benefits of medical actions.
Department of Nuclear Medicine, General Hospital of La Spezia, Italy.
A
A
Coli
M
M
Ferdeghini
R
R
Malvano
G
G
Madeddu
C
C
Prontera
F
F
Scarpato
D005069:Evaluation Studies as Topic; D011933:Reagent Kits, Diagnostic; D013972:Thyrotropin / Q000032:analysis*; D013974:Thyroxine / Q000032:analysis*
D011933:Reagent Kits, Diagnostic; D013972:Thyrotropin; D013974:Thyroxine