Sjögren’s Syndrome (SS) is a chronic autoimmune disorder where the immune system attacks the body’s moisture-producing glands, primarily the salivary and lacrimal glands. This leads to the characteristic symptoms of severe dry mouth and dry eyes, known as sicca symptoms. Since these symptoms overlap with other conditions, a definitive diagnosis requires combining a patient’s clinical presentation with objective laboratory evidence. Blood testing is central to this process, identifying specific markers that indicate a systemic autoimmune response. The final diagnosis integrates these blood test results with physical exams and objective tests measuring glandular function.
Specific Autoantibody Screening
The most specific blood tests for Sjogren’s Syndrome search for autoantibodies, specialized proteins that target the body’s own tissues. The two primary autoantibodies associated with the condition are anti-Ro/SSA and anti-La/SSB. Their presence suggests a specific type of autoimmune activity and is highly valued in diagnostic criteria.
Anti-Ro/SSA antibodies are the most frequently found marker, detected in 60% to 80% of patients. Anti-La/SSB antibodies are less common (30% to 50% of cases) and rarely occur without anti-Ro/SSA also being present. Detecting either or both classifies a patient as having seropositive Sjogren’s Syndrome, which often suggests a higher likelihood of systemic complications.
A negative result for these specific antibodies does not exclude the diagnosis. A significant minority (20% to 40%) are seronegative, meaning they lack anti-Ro/SSA or anti-La/SSB. Seronegative Sjogren’s Syndrome is a recognized subtype that tends to present with symptoms restricted primarily to the exocrine glands. In these cases, the diagnosis relies more heavily on clinical findings and other objective tests.
Supporting Blood Markers for Diagnosis
Several other blood tests are routinely ordered to assess systemic inflammation and immune activity. The Antinuclear Antibody (ANA) test detects antibodies targeting the cell’s nucleus. While a positive ANA result is present in the majority of Sjogren’s patients, it is not specific, as it can be positive in other autoimmune diseases or healthy individuals.
Rheumatoid Factor (RF) is another frequently checked marker, often present in Sjogren’s Syndrome patients, particularly those with secondary Sjogren’s, indicating generalized immune system overactivity. General measures of inflammation are provided by the Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP) tests. These markers reflect inflammation in the body, a common finding in systemic autoimmune diseases.
Clinicians also evaluate blood proteins using serum protein electrophoresis, which may show hypergammaglobulinemia (elevated gamma globulins). This finding suggests an overproduction of antibodies, characteristic of active autoimmune disease. While these supporting tests are not definitive for Sjogren’s, they provide valuable context for a widespread inflammatory or autoimmune process.
Beyond Blood Testing Confirming Sjogren’s Syndrome
Since no single blood test confirms Sjogren’s Syndrome, results are interpreted alongside objective clinical evidence of glandular dysfunction. This is necessary to meet established classification criteria.
Objective tests for ocular dryness typically include the Schirmer’s test, which measures tear production using a strip of filter paper placed under the lower eyelid. Ocular surface staining tests, using specialized dyes, are also performed by an ophthalmologist to assess damage to the eye’s surface caused by chronic dryness.
To confirm salivary gland involvement, a clinician may perform sialometry, a noninvasive test that measures the stimulated or unstimulated flow rate of saliva. A significantly reduced flow rate is objective evidence of salivary gland dysfunction. The most definitive non-blood test is the minor salivary gland biopsy, often taken from the inner lower lip.
The tissue sample from the lip biopsy is examined under a microscope for focal lymphocytic sialadenitis. This involves looking for clusters of inflammatory white blood cells around the small salivary ducts. This specific finding offers histological confirmation of the autoimmune process damaging the glands.
Ultimately, a rheumatologist establishes a diagnosis of Sjogren’s Syndrome. This involves integrating the patient’s clinical symptoms, the presence of specific blood autoantibodies, and the objective findings from these specialized tests to fulfill classification criteria.