Wednesday, June 15, 2022

Anti - Nuclear (ANA) Antibodies , serum

Reference values Modification

Effective update from 20/06/2022

Dear colleagues and collaborators,

The classification of an Antinuclear Antibody (ANA) result as positive or negative is done based on whether it is above a discriminant value or cut-off point. It is recommended that this discriminant value be calculated and adequate for the reference population and methodology of each laboratory.

For this reason, at Synlab, we have carried out a study in our autoimmunity reference laboratories to define which cut-off point produces -with our methodology and in our population- a better diagnostic performance in ANA screening. The results obtained clearly show a better performance of the 1:160 dilution compared to 1:80, both in the evaluation by artificial intelligence systems combined with microscopy, and in the direct observation carried out by expert specialists. The overall specificity data is between 95-97%. These figures are consistent with similar studies.

Consequently, as of 20/06/2022 we will adopt the 1:160 dilution at Synlab as the discriminant value for the ANA screening study, thus joining the recommendations also made by groups of experts and based on the validation carried out in our autoimmunity labs. This change also affects Anticentromere antibodies, since it is the only autoantibody extractable from the nucleus that is also visualized by IIF in Hep-2.

The affected determinations are the following:

Test code: 124 - Anti -Nuclear (ANA) Antibodies , serum
Nemonic code: ACAN


Negative : Titer less than 1/80
Version of Test: 14

Negative : Titer less than 1/160    

Version of Test: 15



Nemonic code: ACEN


Negative : Titer less than 1/80

Version of Test: 5

Negative : Titer less than 1/160   

Version of Test: 6


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