Schmidt’s syndrome, which is also called Schmidt syndrome, was first named after the doctor who discovered the coexistence of Hashimoto’s thyroiditis and Addison’s disease in one of his female patients in 1926. Today, the term Schmidt’s syndrome is also known as autoimmune polyglandular syndrome type II. Schmidt’s syndrome refers to conditions of autoimmune adrenal insufficiency or Addison’s disease occurring in conjunction with one or more of the following conditions: type 1 diabetes, Hashimoto’s thyroiditis, Graves’ disease, or gonadal failure. Schmidt’s syndrome can occur in both humans and canines.
Thyroid disease is the most common glandular disorder to accompany adrenal insufficiency in individuals with Schmidt’s syndrome. Thyroid disease, as a part of Schmidt’s syndrome can occur in the form of chronic autoimmune thyroiditis (Hashimoto’s thyroiditis) or Graves’ disease. Hashimoto’s is much more common and occurs in 95 to 97 percent of patients with Schmidt’s syndrome who develop a thyroid disease. Grave’s disease occurs in 3 to 5 percent of patients who develop thyroid disorders. About 10 percent of patients with Schmidt’s syndrome also develop vitiligo.
Schmidt’s syndrome is based on the fact that if one of the component disorders is present, an associated disorder occurs more commonly than that seen in the general population. The most frequent clinical combination association is Addison's disease and Hashimoto's thyroiditis, while the least frequent clinical combination is Addison's disease, Graves disease, and type 1 diabetes mellitus. The complete tri-glandular syndrome is sometimes referred to as Carpenter's syndrome.
Who Develops Schmidt’s Syndrome?
Schmidt’s syndrome tends to run in families. Among immediate family members it’s not unusual to find more than one person who is affected. The HLA D3, HLA D4 and HLA A1 haplotypes are suspected of causing a genetic predisposition to this disorder.
Schmidt’s syndrome can affect people of all ages although it usually emerges in early adulthood and its incidence peaks at about age 30 to 40 years. Females are affected about three times more often than males. Approximately 14 to 20 people per million population are affected by polyglandular Schmidt’s syndrome. Observations suggest, however, that the disease is much more prevalent if subclinical forms of the glandular disorders are included.
Symptoms and Disease Course
Symptoms of adrenal insufficiency include muscle weakness, apathy, fatigue, appetite loss, weight loss, nausea, vomiting, diarrhea, abdominal pain, low blood pressure (hypotension) that worsens when standing (orthostatic hypotension), hyperpigmentation or bronzing of skin (melasma suprenale), diminished ability to conserve sodium and excrete water, depression, irritability, salt craving, low blood sugar (hypoglycemia), tetany (condition of muscle spasm caused by high phosphorus levels), diminished attention span, and numbness of the extremities due to excess potassium (hyperkalemia). Because most androgens in the female are produced in the adrenal cortex, females with Addison's disease may have decreased genital and underarm hair. Similar to other endocrine deficiencies, most people have a few predominant symptoms and do not develop all associated symptoms. Other symptoms depend on the second glandular disorder. Hypothyroidism, for instance, is associated with joint pain, fatigue, weight gain, constipation, depression, hearing disturbances, insomnia and many other symptoms.
People with Schmidt’s syndrome may also develop myasthenia gravis, pure red cell aplasia, pernicious anemia, seronegative arthritis, primary biliary cirrhosis, alopecia, sarcoidosis, or immunoglobulin A deficiency (which is common in people with celiac disease). Schmidt’s syndrome can also be associated with interstitial myositis, an inflammatory muscle disorder or myopathy.
The underlying autoimmune reaction in Schmidt’s syndrome involves autoantibodies that target the adrenal gland and other endocrine tissues. The autoimmune responses in Schmidt’s syndrome result in inflammation, lymphocytic infiltration, and partial or complete destruction of the glands that are targeted. Usually, one glandular disorder develops before symptoms of the second disorder emerge. The symptoms of the glandular disorders can vary in their severity with one disorder becoming much more prominent. The autoimmune reaction and the associated immune system dysfunction can also damage non-endocrine tissues causing a variety of different conditions such as alopecia or myositis that are associated with Schmidt’s syndrome.
Diagnosis and Treatment of Schmidt’s Syndrome
Diagnosis is made with immunological blood tests that show the presence of adrenal antibodies along with the characteristic autoantibodies and manifestations associated with either autoimmune thyroid disease, diabetes, or gonadal failure.
Treatment is used to correct hormone deficiencies and imbalances. Treatment for one glandular disorder can affect the hormone levels of the second disorder. For this reason, monitoring of treatment should include hormone levels for all glandular disorders present and a complete biochemical profile.
Sources:
Barbara Majeroni and Parag Patel, Autoimmune Polyglandular Syndrome, Type II, American Family Physician 2007; 75: 667-67
Surendra Sivaraja. 2008. Autoimmune Polyglandular Syndrome II, emedicine from WebMD.
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