What is Schmidt syndrome or Autoimmune polyendocrine syndrome type II

Schmidt syndrome also known as Polyglandular autoimmune syndrome type 2 is a rare autoimmune syndrome that commonly has the constellation of three diseases: diabetes mellitus type 1, hypothyroidism and adrenal insufficiency. Owing to the diabetes mellitus type 1, patients require life-long insulin therapy and blood glucose levels need to be monitored. They are at risk for chronic complications of diabetes such as neuropathy, nephropathy and retinopathy. More acutely, due to fluctuations in blood glucose levels, they are at risk for hypoglycemia with neuroglycopenic symptoms and ketoacidosis. Hypothyroidism is diagnosed by measuring the thyroid hormone levels and if inappropriately low is treated with replacement therapy. Patients with adrenal insufficiency experience symptoms due to low glucocorticoid and mineralocorticoid levels in the body, due to decreased or absent production.

See also Polyglandular syndromes type I, II, III

Autoimmune polyglandular syndrome type 2 is an autoimmune disorder that affects many hormone-producing (endocrine) glands.[1] It is characterized by the presence of Addison’s disease along with autoimmune thyroid disease and/or type 1 diabetes.[1] Affected individuals may also have problems with other endocrine glands and other common features include primary hypogonadism, myasthenia gravis, and celiac disease. Autoimmune polyglandular syndrome type 2 is diagnosed in adulthood, typically around age 30.[2] The cause of autoimmune polyglandular syndrome type 2 is unknown, although it may involve a combination of genetic and environmental factors. This condition occurs more often in women than men. About 10% of patients with APS-2 and Addison’s disease had a relative with adrenal insufficiency, and about 10% of patients with APS-2 and type 1 diabetes had a sibling with the same disease, and, or with autoimmune thyroid disease.[1][3]

Currently, there are no unique tests to detect APS-2, but testing for autoantibodies may be helpful in assessing disease risk, since the relevant autoantibodies (such as antibodies to thyroid peroxidase in autoimmune thyroid disease, or to glutamic acid decarboxylase in type 1 diabetes) are frequently detectable years before disease onset. Treatment is mainly with hormone replacement therapy.[1][3][2]

This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
https://rarediseases.info.nih.gov/diseases/7611/autoimmune-polyglandular-syndrome-type-2