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None of 3 assays on an Abbott Alinity can meet preferred measurement uncertainty goals

A recent study of Abbott Alinity thyroid function tests can be evaluated against the EFLM MAU and the preferred permissible uncertainties proposed by the leading authorities on mu.

Zero of 3 thyroid function assays on an Abbott Alinity cannot meet preferred measurement uncertainty goals

March 2023
Sten Westgard, MS

A recent letter to the editor in JALM benchmarked Abbott Alinity assays against the most recent preferred measurement uncertainty performance standards.

Measurement Uncertainty of Thyroid Function Tests on a Chemiluminescent Microparticle Immunoassay System Needs to be Improved. Borrillo F, Pasqualetti S, Panteghini M. JALM March 2023 08:02, 420-422.

This study looks at two Abbott Alinity instruments. and their individual performance as well as the performance measured between platforms. 

The sources for these measurement uncertainty performance specifications can be found in these references:

There are just 3  thyroid function assays covered in the paper: TSH, FT3, and FT4. A single level of performance is measured for each of 2 Alinity analyzers, as well as a between-platform imprecision. So for each assay, there will be three measurements. The 2022-2023 papers from Panteghini et al provide the definitive, preferred specifications for permissible uncertainy (pU, or as well will refer to them, ppU). The EFLM  database provides specifications for MAU, minimum and desirable, for all 3 analytes.

Abbott Alinity
Level MU EFLM Desirable,
Minimum MAU
Preferred pU (ppU)
Final verdict
TSH   i08 5.38% 26.5% (des)
17.7% (min)  

2.89% (des)
4.34 (min)

Fails ppU
i09  3.98% Fails des ppU
between-platform 4.77% Fails ppU
FT3 i08 5.99% 5% (des)
7.5% (min)
2.35% (des)
3.53% (min) 
Fails des MAU and ppU
i09 4.36% Fails ppU
between-platform 5.24% Fails des MAU and ppU
FT4 i08  5.17% 4.9% (des)
7.4% (min)
2.8% (des)
4.2% (min)
Fails des MAU and ppU
i09  4.88% Fails ppU
between-platform 5.09% Fails des MAU and ppU

Notice that these assays always pass some form of the MAU, whether it is desirable or minimum, but always fail the ppU goals.

As we have seen with other assays, and other instruments, these new measurement uncertainty performance standards are harsh, perhaps impractically harsh, beyond the capability of even the most advanced instruments. That should raise concerns about the promulgation and mandatory implementation of these new goals throughout the world.