Autoimmune polyendocrinopathy type 2

Autoimmune polyendocrinopathy type 2 (APS-2), also known as Schmidt syndrome or autoimmune polyglandular syndrome type 2, is a condition in which the immune system mistakenly attacks multiple endocrine (hormone-producing) glands in the body. It is the most common form of autoimmune polyglandular syndrome. APS-2 is defined by the occurrence of Addison disease (autoimmune adrenal insufficiency) in combination with autoimmune thyroid disease (Hashimoto thyroiditis or Graves disease) and/or type 1 diabetes mellitus. Addison disease, which involves destruction of the adrenal glands, is considered the hallmark feature and leads to fatigue, weight loss, low blood pressure, and skin hyperpigmentation. Beyond the core endocrine features, patients may also develop other autoimmune conditions including primary hypogonadism (premature ovarian failure or testicular failure), celiac disease, vitiligo, autoimmune gastritis with pernicious anemia, myasthenia gravis, and alopecia. The condition typically presents in adulthood, most commonly between the ages of 20 and 60, and is more frequent in women than men. The various component diseases may not all appear simultaneously; they can develop over years or even decades, making ongoing surveillance important. APS-2 has a complex, multifactorial inheritance pattern with strong associations with specific HLA genotypes, particularly HLA-DR3 and HLA-DR4. It tends to cluster in families, suggesting a significant genetic predisposition, though environmental triggers also play a role. There is no cure for APS-2; treatment involves hormone replacement therapy for each deficient gland — hydrocortisone and fludrocortisone for adrenal insufficiency, levothyroxine for hypothyroidism, and insulin for type 1 diabetes. Regular screening for additional autoimmune conditions is recommended for affected individuals and at-risk family members. With appropriate lifelong management, patients can maintain a good quality of life.

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