ESPE Abstracts

Objectives: To investigate sensitivity, specificity and predictive values (PPV, NPP) of autoantibodies against 21-hydroxylase in APECED patients with and without adrenal insufficiency (AI) and in patients with other forms of AI.

Methods: 42 patients with APECED and 24 patients with other forms of AI were recruited. APECED was confirmed by finding at least two major components of the disease and/or two mutations in AIRE gene and/or high levels of antibodies against interferon-ω. APECED in patients with other forms of AI were excluded by performing genetic test and/or investigating antibodies against interferon-ω. All patients were tested for autoantibodies against 21-hydroxylase by ELISA.

Results: 67% (28/42) patients with APECED had AI. Autoantibodies against 21-hydroxylase were significantly associated with AI (P<0.0001). Specificity was 79%, sensitivity – 82%, PPV – 88%, NPV – 69%. Two patients had positive 21-hydroxylase antibodies before the manifestation of AI (AI was diagnosed one year after blood sampling). The level of antibodies has negative correlation with duration of AI by the time of the blood sampling (Spearman −0.396, P<0.05). 60% (3/5) patients with AI and negative for 21-hydroxylase antibodies were tested more than 15 yrs after the debut of the AI. 71% of non-APECED patients with AI (17/24) were positive for 21-hydroxylase antibodies, and all of them were diagnosed autoimmune AI. Seven patients were negative for 21-OH autoantibodies, congenital adrenal hypoplasia due to DAX-1 gene mutations was confirmed in two of them, X-linked adrenoleukodystrophy in one patient. In four patients the cause of AI was not clarify.

Conclusions: Detection of autoantibodies against 21-hydroxylase is a reliable method to screen for autoimmune AI and could be recommended also for prediction of AI manifestation in patients with APECED.