Arthritis: Sjögren's syndrome
Sjögren's syndrome is a chronic disorder that causes insufficient moisture production in certain glands of the body. It occurs when a person's normally protective immune system attacks and destroys moisture-producing glands, including salivary glands and tear glands. The lungs, bowel and other organs are affected occasionally.
Sjögren's syndrome is named after the Swedish eye doctor, Henrik Sjögren, who first described the condition.
Sjögren's syndrome may cause the following symptoms:
- Extremely dry eyes causing a feeling of grit or sand in the eyes or a burning redness.
- Extremely dry mouth and throat causing difficulty with chewing and swallowing, decreased sense of taste, difficulty speaking, an increase in dental cavities, and dry cough or hoarseness.
- Enlarged parotid glands (located at the angle of jaw) and sometimes infection of these glands.
- Excessive fatigue
- Aches and pains in muscles and joints
Less common features of Sjögren's syndrome are:
- Irritation of the nerves in the arms, hands, legs or feet ( neuropathy).
- Thyroid gland abnormalities
- Skin rashes
- Memory loss or confusion.
- Numbness or tingling.
- Gastrointestinal problems.
- Inflammation of the lungs, kidneys, liver or pancreas.
- Cancer of the lymphatic tissue ( lymphoma) occurs in less than 1% of patients.
What causes Sjögren's syndrome?
Normally, the immune system (the body's defence against invaders) protects the body from infection and foreign substances such as bacteria and viruses.
In autoimmune diseases, such as Sjögren's syndrome, the immune system triggers an inflammatory response when there are no foreign substances to fight off. This inflammatory response causes the body's white blood cells to attack and destroy certain moisture-producing glands.
The exact cause for the abnormal immune response in Sjögren's syndrome is unknown. Some theories suggest that a virus or bacteria may alter the immune system, causing it to attack the glands. Some people may have a genetic or inherited factor that makes them more likely to develop Sjogren's syndrome.
What are the forms of the disease?
Sjogren's syndrome occurs in two basic forms: primary Sjögren's syndrome, the disease by itself and not associated with any other illness, and secondary Sjögren's syndrome, disease that develops in the presence of another autoimmune disease such as rheumatoid arthritis, lupus, or vasculitis.
Sjögren's syndrome affects about half a million people in the UK. More than 90% of these are women. The disease can affect people of any race or age, although the average age of onset is in the late 40s.
How is Sjögren's syndrome diagnosed?
The diagnosis of primary Sjögren's syndrome is based on several factors, including:
- Presence of dry eyes and mouth. An ophthalmologist can detect dry eyes by measuring tear production or carefully examining the cornea of the eye.
- Certain laboratory tests also suggest that dry eyes and mouth are caused by autoimmune mechanisms. Examples include the presence of auto-antibodies in the blood, known as anti-SSA or anti-SSB (also called anti-Ro or anti-La).
- Biopsy of the inner lip (performed in some cases to prove the diagnosis of primary Sjögren's syndrome). The biopsy may show inflammation damaging salivary glands.
Secondary Sjögren's syndrome is generally diagnosed when someone with an established autoimmune disease, such as rheumatoid arthritis or lupus, develops extreme dryness of the eyes and mouth. This diagnosis only rarely requires a lip biopsy.