21-hydroxylase autoantibodies in adult patients with endocrine autoimmune diseases are highly specific for Addison's disease

Abstract

SUMMARY The diagnostic specificity of recombinant 21-hydroxylase autoantibodies (21OH-Ab) for Addison's disease was tested in adult patients with either Graves' disease (GD), insulin-dependent diabetes mellitus (IDDM), or polyendocrinopathy, as well as in healthy controls. Using a radiobinding assay with in vitro translated recombinant human 21-hydroxylase, we found 21OH-Ab in 24/28 (86%) idiopathic Addison patients, and using an immunofluorescence assay we found adrenal cortex autoantibodies (ACA) in 12/28 (43%) patients (P =0.002). All the 12 ACA-positive sera were also positive for 21OH-Ab and ACA were found in 11/15 (73%) patients with less than 15 years and in 1/13 (8%) patients with 15–38 years of disease duration (P = 0.002). 21OH-Ab were present in 3/92 (3%) patients with GD, in 1/180 (0.6%) with IDDM and in 0/106 healthy subjects. The 21OH-Ab-positive GD and IDDM patients were also positive for ACA. None of 17 patients with polyendocrinopathy, but without Addison's disease, had 21OH-Ab. None of the 180 Belgian IDDM patients had Addison's disease or developed an adrenal insufficiency at follow up. In two out of three Graves patients, the presence of 21OH-Ab was associated with clinical and biochemical signs of adrenal insufficiency. Of the 89 21OH-Ab-negative patients with GD none had Addison's disease at the time of blood sampling, and 79 were followed up for 5.6–7.5 years and none developed clinical signs of adrenal insufficiency. We conclude that the presence of 21OH-Ab in patients with endocrine autoimmune diseases is highly specific for Addison's disease.