Draft:Parallelism (laboratory test)

= Parallelism (laboratory test) = Parallelism, in the context of laboratory research refers to the degree to which different samples or assays produce consistent and proportional results, ensuring that comparisons and measurements are accurate and reliable across different conditions or experiments.

Definition of Parallelism for a laboratory test
This section is about parallelism in a specific type of test done in a laboratory. These tests, called quantitative laboratory tests, figure out how much of a substance is in a sample. For instance, they might measure how much glucose is in a blood sample. No matter the method used, it is mandatory to figure out the unknown concentration in the sample by comparing it to a known standard. This is done mathematically using regression analysis. For the mathematics to be right, the serial dilution curve of the substance in the sample has to match up with the dilution curve of the standard. So, in laboratory tests, parallelism means there is a similar relationship between the substance being measured (like a biomarker) and the signal from the standard.



Regulatory authorities
Regulatory authorities such as the Food and Drug Administration (FDA) and European Medicines Agency (EMA) have made presence of parallelism mandatory for the approval of analytical methods used in medicine. Guidelines have been produced for the approval of bioanalytical methods that indicate how parallelism tests should be evaluated.

Determination of parallelism
Parallelism of a laboratory test can be determined visually or statistically. . Each method has there advantages and limitations. For people without a statistical background the visual assessment is likely more intuitive

Presence of parallelism
Presence of parallelism is important for the reliable and accurate reporting of data. In routine laboratory practise parallelism can frequently be demonstrated for at least a partial range of the analyte. . Therefore partial parallelism plots give a quick visual answer. An example is given for presence of parallelism comparing the dilution curve of a reference standard with the dilution curve of several samples. All horizontal lines in the figure are parallel between the red vertical reference lines



Absence of parallelism
Absence of parallelism is a problem because calculations may not be valid. An example for lack of parallelism is shown. The sample dilution curves are not parallel to the horizontal dilution curve of the reference standard.