Autoantibodies to 21-hydroxylase as a diagnostic marker of primary autoimmune adrenal insufficiency, including at its potential and latent stages

Rationale: In Russia, assessment of anti-P450c21 antibodies (AB) in the diagnosis of autoimmune adrenal insufficiency (AAI) has not been commonly used, and the disease screening has not been implemented.Aims: 1) To determine the sensitivity and specificity of anti-P450c21 AB determination in the AAI diagnosis; 2) To estimate the prevalence of anti-P450c21 AB carriage in patients without AAI.Materials and methods: Anti-P450c21 AB were assessed in 40 patients (group 1) with manifest AAI; 171 patients without established diagnosis of AAI, including 113 subjects with autoimmune thyroid disorders or type 1 diabetes mellitus (AID, group 2); 25 carriers of AB markers of thyroid AID and/or type 1 diabetes mellitus without any target organ dysfunctions (group 3); 33 patients with non-autoimmune endocrine disorders (group 4), and 25 healthy individuals (group 5).Results: Determination of anti-P450c21 AB for the diagnosis of AAI had 95% sensitivity, with specificity of 100%, predictive value of a positive result of 100%, and predictive value of a negative result 92.6%. Anti-P450c21 AB were inversely correlated with the duration of glucocorticoid replacement therapy (r=-0.222, p