What are the key laboratory tests to consider when evaluating a patient with suspected autoimmune disease?

When evaluating a patient with suspected autoimmune disease, the key laboratory tests to consider are highly dependent on the specific condition suspected NICE NG20,NICE CKS,NICE CKS. For instance, in cases where Systemic Lupus Erythematosus (SLE) is suspected, the evaluation of anti-dsDNA antibodies is a key consideration Cockx et al. 2022. However, it is important to note that some autoimmune diseases can be seronegative, meaning typical autoantibodies may not be present, posing a diagnostic challenge Lenti et al. 2022.

For suspected coeliac disease, initial tests typically include tissue transglutaminase (tTG) antibodies, and if these are positive, endomysial antibodies (EMA) may also be considered NICE NG20,NICE CKS. In the context of suspected type 1 diabetes, relevant autoantibodies include islet cell antibodies (ICA), glutamic acid decarboxylase (GAD) antibodies, insulin autoantibodies (IAA), and tyrosine phosphatase-like antigen (IA-2) antibodies NICE CKS,NICE CKS. The absence of typical serological markers does not always rule out an autoimmune condition, especially in the case of seronegative autoimmune diseases Lenti et al. 2022.