Autoimmune polyglandular syndrome (APS) is a rare collection of conditions caused by the body’s immune system mistakenly attacking its own endocrine system. The endocrine glands produce and secrete hormones that are involved in metabolism and growth. APS can cause disrupt many of the processes that are important to everyday life. In some cases, it can be fatal.

APS is a combination of several disorders that affect the endocrine glands at the same time. It may also involve non-endocrine disorders. Three types of APS are recognized, although the disorders that appear can vary between types and among patients:

• Type I APS is often associated with a type of yeast infection, hypoparathyroidism and Addison’s disease. It usually begins in infancy, although it may not be diagnosed until much later, after more disorders develop.
  
  
• Type II APS is the most common and most varied type. Disorders common to type II are Addison’s disease, type 1 diabetes and autoimmune  thyroiditis, though many other disorders may also occur. It may appear anywhere from infancy through adulthood.
  
  
• Type III APS is extremely rare. It affects newborns and is often fatal. Type 1 diabetes and malabsorption are associated with this form of APS.

The primary causes of APS appear to be genetic. Diagnosis can begin with a physical examination and medical history. Patients with one or more autoimmune diseases, or with a family history of autoimmune disease may be suspected of APS. Confirmation may be possible through blood tests for genetic indicators and abnormal hormone levels.