Autoimmunity as the Most Frequent Cause of Idiopathic Secondary Adrenal Insufficiency: Report of 111 Cases

The origin of the isolated secondary adrenal insufficiency is unknown in most cases. An observation of a group of over 100 patients with secondary adrenal insufficiency and coexisting autoimmune abnormalities suggests that autoimmunity could be a frequent cause of idiopathic secondary failure, similarly as in Addison's disease. We studied 176 patients with idiopathic isolated secondary adrenal insufficiency. The methods included clinical examination and measurements of pituitary, adrenal, thyroid and gonadal hormones in all the cases. Since thyroid autoimmunity has been the most frequent finding in Addison's disease we have also chosen thyroid autoantibodies as markers of an autoimmune process in our material. Anti-peroxidase, anti-microsomal and anti-thyroglobulin autoantibodies were determined in 151 patients. In 111 out of 151 patients (73%) coexisting autoimmune diseases and/or presence of thyroid autoantibodies were detected. The most frequent autoimmune diseases associated with secondary adrenal insufficiency were primary hypothyroidism, hyperthyroidism (mainly in the past) and premature ovarian failure. Thyroid autoantibodies, especially antiperoxidase autoantibodies, were present in 106 patients. Thus, coexistence of isolated secondary adrenal insufficiency with some autoimmune disorders in 73% of the patients under study suggests that autoimmunity is the most frequent cause of the idiopathic form of this disease.