How low can we (reliably) go? A method comparison of thyroid-stimulating hormone assays with a focus on low concentrations
Authors' conclusion
We established the standardization differences of frequently used TSH assays for the total and low concentration ranges. Based on the proportional bias and the imprecision, this effect seems to have limited clinical consequences for the low TSH concentration range. Nevertheless, as guidelines mention absolute TSH values to guide clinical decision-making, caution must be applied when interpreting values close to these cut-offs.
Study context
- Population
- Samples covering a wide range of thyroid-stimulating hormone (TSH) concentrations (<0.01 to 120 mIU/L), oversampled in the lower range (<0.4 mIU/L)
- Participants
- 60 samples
- Comparison
- Three TSH immunoassays
- Outcome
- Standardization differences (bias) between TSH immunoassays
Main finding
As reported in the abstract
Bias, total range
7-16%
Bias, low range
1-14%
Different classification of TSH concentrations <0.40 mIU/L measured over last 6 months, at cut-off TSH = 0.1 mIU/L
1.5%
Further findings
Imprecision (CV from duplicate measurements, 20 samples)
- Imprecision of the immunoassays
- 1.6-5.5%
- Could lead to a reclassification similar to that from bias between immunoassays
Original publication
Composed by AI from the published abstract and checked against it. How Briefs are made →