Autoimmune polyendocrine syndrome type 2

Autoimmune Polyendocrine Syndrome Type 2 (APS-2), also known as Schmidt's syndrome, is a complex autoimmune disorder characterized by the coexistence of at least two autoimmune diseases, including Addison's disease, thyroid autoimmune diseases (such as Graves' disease or Hashimoto's thyroiditis), and type 1 diabetes mellitus. This syndrome is more common in females and typically presents in adulthood.

Etiology and Pathogenesis

The exact cause of APS-2 is unknown, but it is believed to involve a combination of genetic predisposition and environmental factors. The HLA-DQ gene is often associated with the syndrome, suggesting a strong genetic component. Environmental triggers may include viral infections, stress, and other unknown factors that initiate an autoimmune response in genetically susceptible individuals.

Clinical Manifestations

APS-2 presents with a variety of symptoms depending on the specific autoimmune diseases involved. Common manifestations include:

• Addison's disease symptoms: fatigue, weight loss, skin hyperpigmentation, low blood pressure, and salt craving.
• Thyroid autoimmune diseases symptoms: depending on whether the patient has Graves' disease (hyperthyroidism) or Hashimoto's thyroiditis (hypothyroidism), symptoms can include weight changes, mood swings, heat or cold intolerance, and changes in heart rate.
• Type 1 diabetes mellitus symptoms: increased thirst and urination, weight loss, fatigue, and blurred vision.

Diagnosis

Diagnosis of APS-2 involves a combination of clinical evaluation and laboratory tests. Key diagnostic tests include:

• Autoantibody tests: to detect antibodies against the adrenal cortex, thyroid, and pancreatic islet cells.
• Hormone level tests: to assess the function of the affected glands (e.g., cortisol, thyroid hormones, and insulin).
• Imaging studies: such as ultrasound or CT scans, may be used to evaluate the structure of the thyroid gland and adrenal glands.

Treatment

Treatment of APS-2 focuses on managing the symptoms of the individual autoimmune diseases involved and may require a multidisciplinary approach. Common treatments include:

• Corticosteroids: for Addison's disease to replace the deficient hormones.
• Thyroid hormone replacement therapy: for Hashimoto's thyroiditis.
• Antithyroid drugs or radioactive iodine therapy: for Graves' disease.
• Insulin therapy: for type 1 diabetes mellitus.

Regular monitoring and adjustments of therapy are essential due to the progressive nature of these autoimmune diseases.

Prognosis

With appropriate treatment and monitoring, individuals with APS-2 can manage their symptoms and maintain a relatively normal quality of life. However, they must remain vigilant for the development of additional autoimmune diseases.

Epidemiology

APS-2 is less common than Autoimmune Polyendocrine Syndrome Type 1 (APS-1) but is more prevalent in certain populations, particularly those of Northern European descent. It typically presents in adulthood, with a higher incidence in females.

See Also

• Autoimmune Polyendocrine Syndrome Type 1
• Autoimmune disease
• Endocrine system