Adrenal Cortex Antibodies
Autoimmune Polyendocrine disorders
75-85% patients with idiopathic Addison’s disease have circulating antibodies to adrenal antigens at the time of diagnosis. The antibodies are predominantly IgG class and, in general, have rather low titres (not higher than 100). The prevalence rises to 90% in patients with hypoadrenalism and primary ovarian failure. Measurement is useful in determining adrenal involvement in autoimmune polyendocrine syndromes (APS).The Cytochrome P450 enzyme, 21-hydroxylase is believed to be the major antigen recognised by anti-adrenal autoantibodies in Addisons disease. This enzyme converts 17-α progesterone and progesterone into 11-deoxycortisol and deoxycorticosterone. Other cytochrome P450s might also be involved in autoimmune polyendocrine syndromes and other adrenal autoantigens have been reported.
Investigation aetiology of Addison’s disease and polyglandular autoimmunity.
Raised titres are suggestive of an autoimmune cause of Addison’s disease. They are not usually found in TB associated adrenal failure or secondary carcinoma. Addisons disease is often associated with other autoimmune disorders forming part of autoimmune polyendocrine syndromes (APS). APS1 is a triad of Addisons disease, hypoparathyoidism and chronic mucocutaneous candidiasis (CMC): Type II APS is associated with primary hypothyroidism and/or type 1 diabetes. Autoimmune gastritis can also be associated.
Anti-adrenal antibodies can be found in around 2% of children with insulin dependent diabetes and patients with chemical evidence of adrenocortical disease but without overt Addisons disease.
They are very rare in normal individuals (0.6%), usually in older women.
Serum Separator Tube (SST)
Indirect immunofluorescence using primate tissue.
Assay range notes
Negative titre <10