Sjögren’s syndrome is a chronic autoimmune disease that mainly affects middle-aged women. As with other autoimmune diseases, the immune system mistakenly attacks the body’s own cells and tissues.
The disease presents a diagnostic challenge, as its exact cause is unknown and its symptoms mimic those of other conditions.
Furthermore, not all symptoms may appear at the same time, causing healthcare practitioners to treat symptoms individually, without recognizing the presence of a more systemic disorder. A physician examining a patient’s joint pain, for instance, may not see their dry skin. Similarly, an eye doctor treating dry eyes may not associate that symptom with dryness elsewhere, with joint pain, or with other symptoms.
Because of these challenges, no single test will confirm the diagnosis of Sjögren’s. Rather, the disorder is typically diagnosed through a series of tests and questions.
Blood and urine tests
A blood test can reveal the presence of antibodies associated with Sjögren’s syndrome, markers of inflammation (common in autoimmune disorders), markers of liver and kidney damage, and the levels of certain types of blood cells.
Approximately 70%–80% of people with Sjögren’s syndrome produce anti-Ro (SS-A) and anti-La (SS-B) antibodies. These antibodies, however, are not specific to Sjögren’s syndrome, and may also be found in patients with other autoimmune conditions and in healthy people.
Other blood tests look for the presence of antibodies against proteins in the nucleus, antibodies common to rheumatoid arthritis (which many Sjögren’s syndrome patients share), and antibodies against the thyroid (antibodies that can be produced when white blood cells infiltrate the organ and trigger inflammation).
Inflammation involved in Sjögren’s syndrome can cause damage to the kidneys, which may be detected through a urine analysis. A doctor will look for signs such as poorly concentrated urine, increased protein content, and sometimes a high pH. Less commonly, red and white blood cells may also find their way into the urine.
Eye tests
Doctors typically measure tear gland function through a Schirmer’s test. One end of a thin paper strip is inserted under the lower eyelid of each eye. Numbing drops, given before applying the strips, will prevent tearing from irritation caused by the paper.
The patient closes their eyes for five minutes, after which the physician will measure the amount of wetness on each strip. Usually, under 5 mm of wetness on the strip indicates low tear production.
A Rose-Bengal Stain uses sodium to identify injuries on the eye, particularly of the cornea — the transparent layer covering the pupil, iris, and anterior chamber (the fluid-filled chamber inside the eye).
A slit-lamp exam provides another way to look for dryness and physical damage. Doctors also use a non-toxic stain (lissamine green or fluorescein) that shows the extent of changes to the ocular surface associated with excessive dryness. These are then observed through a microscope with an intensely bright light to get a three-dimensional look into a patient’s eye.
Imaging tests
A salivary gland scan known as a parotid gland scintigraphy uses radiation to measure saliva production. A patient is injected with a low level of a radioactive marker that infuses the saliva and enters the glands, and is then made to salivate using a sour substance such as a lemon drop. Images are taken before and after the sour fluid and salivation is measured by changes in radiation passing through the parotid glands.
A sialography test, or sialogram, is similar but uses X-rays to observe the salivary glands and ducts. It uses a dye that shows up in x-ray images rather than a radioactive substance.
Changes in the structure of salivary glands can be detected with an ultrasonography, which uses high-frequency sound waves to visualize the major salivary glands.
A chest X-ray and magnetic resonance imaging of the brain and spinal cord may also be ordered to evaluate other manifestations of Sjögren’s syndrome, such as pulmonary lesions or neurologic complications.
Biopsy
Patients may need to undergo a biopsy of the tear or salivary glands, meaning that a tiny amount of tissue is removed to look for patterns of inflammatory cells, and severity of inflammation. Lip biopsies tend to be preferred over tear biopsies.
Alternately, a biopsy may be taken from the parotid glands, which are salivary glands located just below the ears.
Patient medical history
Finally, questions about the length of symptoms can provide important diagnostic information.
A doctor will want to know how long a patient has experienced dry eye, whether it feels like something is in the eye, and how often a patient uses artificial tears.
Similarly, a physician might ask how long an individual has experienced dry mouth, and whether they can feel any swelling of the salivary glands or need to use liquids when swallowing food.
Last updated: May 4, 2021
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