What is Sjögren syndrome?
Sjögren syndrome is an autoimmune disorder in which the body's immune system mistakenly reacts to the tissue in glands that produce moisture, such as tear and salivary glands. It is a chronic, inflammatory disease that often progresses to a more complex, systemic disorder that can affect other tissues and organs in the body such as joints, skin, kidneys, lungs, nervous system, and the intestinal tract. Sjögren syndrome is characterized by an unusual accumulation (infiltration) of a particular type of white blood cell, lymphocytes, in the glands that are responsible for fluid production.
Sjögren syndrome affects the amount and quality of saliva and tears produced by glands, leading to distinctive features, including a dry mouth and dry eyes, that are referred to as "sicca syndrome." Other mucous membranes may also become abnormally dry. People with this condition often have a feeling of sand or grit in the eyes, swollen salivary glands, difficulty swallowing, and a decreased sense of taste.
Sjögren syndrome can affect anyone at any age, but the majority of those afflicted are older than 40, and women are nine times more likely than men to have the disorder. It is estimated to be the second most common autoimmune disease, after lupus. According to the National Institute of Neurological Disorders and Stroke (NINDS), between 1 and 4 million people in the United States have Sjögren syndrome.
The cause of Sjögren syndrome is not known, but researchers think it may be a combination of genetic and environmental factors. It is thought that a trigger such as a bacterial or viral infection may prompt development of Sjögren syndrome in some people who are genetically predisposed to the disorder.
The disorder may present as primary or secondary disease, with all cases divided roughly in half between the two:
- Primary Sjögren syndrome—develops gradually with salivary and tear gland function worsening over time and without any other underlying disorder
- Secondary Sjögren syndrome—occurs when a person already has an autoimmune disorder, such as lupus, polymyositis, scleroderma, or rheumatoid arthritis
Complications can develop in relation to Sjögren syndrome and may include salivary gland infections and tumors, dental cavities, damage to the eyes, kidney disease, and lung infections. Pregnant women who have autoantibodies related to Sjögren syndrome may have a higher risk of miscarriage. Sjögren syndrome has also been associated with a higher risk of developing lymphoma.
The Sjögren's Syndrome Foundation says that reaching a diagnosis can be difficult and often takes an average of about 4 years from the onset of symptoms. The American-European Consensus Group and the Sjögren's International Collaborative Clinical Alliance (SICCA) each developed criteria to help health practitioners in making a diagnosis of Sjögren syndrome. The American College of Rheumatology (ACR) adopted the SICCA criteria in 2012. Criteria for diagnosis include, for example, signs and symptoms and positive tests for ANA, anti-SSA and anti-SSB, and/or RF as well as a positive salivary gland biopsy. (See the Tests section for more on these.)