Sjögren's Syndrome - Common Tests for Diagnosis
In Rheumatoid Arthritis and Sjögren's Syndrome, we discussed how patients living with RA have an increased risk of developing secondary Sjögren's Syndrome (SS). Early diagnosis and treatment are important for the prevention of complications in Sjögren's. However, reaching a diagnosis can often be difficult and may take an average of six and a half years from the onset of symptoms, according to the Sjögren's Syndrome Foundation.
Sjögren's syndrome symptoms frequently overlap with or "mimic" those of other diseases including lupus, rheumatoid arthritis, fibromyalgia, chronic fatigue syndrome and multiple sclerosis. Dryness can also occur for other reasons, such as a side effect of medications such as anti-depressants and high blood pressure medication.
There is no single test that will confirm diagnosis. Your doctor will base a diagnosis on medical history, physical exam, combination of symptoms, and results from clinical and laboratory tests. A rheumatologist is often responsible for diagnosing and managing Sjögren's Syndrome. Criteria for diagnosis considers dryness symptoms, changes in salivary (mouth) and lacrimal (eye) gland function, and systemic (whole body) findings.
Common eye tests include:
- Schirmer test - This test measures tear production to see how the lacrimal (tear) glands are working. The doctor puts thin paper strips under the lower eyelids and measures the amount of wetness on the paper after 5 minutes. People with Sjögren's syndrome usually produce less than 8 millimeters of tears.
- Staining with vital dyes (rose bengal or lissamine green) - These tests show the extent to which dryness has damaged the surface of the eye. To perform one of these tests, the doctor puts a drop of a liquid containing a dye into the lower eyelid. The dye stains the surface of the eye, highlighting any areas of injury, thereby allowing the doctor to see with the slit lamp how much damage has occurred on the surface of the eye.
- Slit lamp examination - This test, in which an ophthalmologist uses equipment to magnify and carefully examine the eye, shows how severe the dryness is and whether the outside of the eye is inflamed.
Common mouth tests include:
- Mouth exam - The doctor will look outside the mouth for signs of major salivary gland swelling and inside the mouth for signs of dryness. Signs of dry mouth include a dry, sticky lining (called oral mucosa); dental caries (cavities) in characteristic locations; thick saliva, or none at all coming out of the major salivary ducts; redness of the mouth lining, often associated with a smooth, burning tongue; and sores at the corners of the lips. The doctor might also try to get a sample of saliva, to check its quality and see how much of it the glands are producing.
- Salivary gland scintigraphy - A nuclear medicine test that measures salivary gland function.
- Lip biopsy - This test is the best way to find out whether dry mouth is caused by Sjögren's syndrome. To perform this test the doctor removes tiny minor salivary glands from the inside of the lower lip and examines them under the microscope. If the glands contain white blood cells in a particular pattern, the test is positive for the salivary component of Sjögren's syndrome.
Blood tests may include:
- Routine blood tests - The doctor will take a blood sample to look for levels of different types of blood cells, check blood sugar level, and see how the liver and kidneys are working.
- Erythrocyte Sedimentation Rate (ESR): This test measures inflammation. An elevated ESR indicates the presence of an inflammatory disorder, including Sjögren's syndrome.
- Other blood tests - Various blood tests may be performed to check for antibodies and other immunological substances often found in the blood of people with Sjögren's syndrome. Antibodies are gamma globulin molecules, called immunoglobulins, which are important for fighting infection. Everyone has these in their blood, but people with Sjögren's syndrome usually have too many of them. Antibodies that are directed against the individual making them are called auto antibodies.
Antibodies that may be present in people with Sjögren's syndrome include the following.
- Immunoglobulins (IGs): These are normal blood proteins that participate in immune reactions. The three main classes of immunoglobulins can be measured to see if there is a general increase in antibodies.
- Anti-thyroid antibodies: Auto antibodies against the thyroid gland are created when white blood cells (lymphocytes) migrate into the thyroid gland, causing thyroiditis (inflammation of the thyroid), a common problem in people with Sjögren's syndrome.
- Rheumatoid factors (RF): These are auto antibodies commonly found in the blood of people with rheumatoid arthritis as well as in people with Sjögren's syndrome and other autoimmune connective tissue diseases. In Sjögren's patients, 60-70 percent have a positive RF.
- Antinuclear antibodies (ANAs): These are auto antibodies that react against normal components of a cell nucleus. The presence of ANAs in the blood can indicate an autoimmune disorder, including Sjögren's syndrome. About 70 percent of Sjögren's patients have a positive ANA test result.
- Sjögren's antibodies, anti-SS-A (or -Ro) and anti-SS-B (or -La): These are specific antinuclear antibodies that occur commonly, but not always, in people with Sjögren's syndrome. 70 percent of Sjögren's patients are positive for SS-A and 40 percent are positive for SS-B (these may also found in lupus patients).
Other possible tests include:
- Chest x ray - Sjögren's syndrome can cause inflammation in the lungs, so the doctor may want to take an x ray to check them.
- Urinalysis - The doctor will probably test a sample of your urine to see how well the kidneys are working.
Resources: Sjögren's Syndrome Foundation: Diagnosis