From the Guidelines
The most appropriate laboratory tests for diagnosing Sjögren's syndrome include anti-Sjögren syndrome A antibody (SSA or anti-Ro), anti-Sjögren syndrome B antibody (SSB or anti-La), rheumatoid factor, and antinuclear antibody, as well as additional biomarkers such as salivary protein 1 (SP1), carbonic anhydrase 6 (CA6), and parotid secretory protein (PSP) 1. When diagnosing Sjögren's syndrome, it is essential to consider the patient's symptoms, such as dry eyes and dry mouth, and to rule out other conditions with similar symptoms.
- The most common blood tests for Sjögren's syndrome include:
- Anti-Ro/SSA and anti-La/SSB antibodies, which are present in about 70% of Sjögren's patients
- Rheumatoid factor (RF) and antinuclear antibody (ANA) tests, which are often positive in Sjögren's syndrome
- Other useful tests include:
- Complete blood count (CBC) to detect anemia or elevated inflammatory markers
- Immunoglobulin levels, which may be elevated
- Complement levels (C3, C4), which might be decreased
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to indicate inflammation
- For more definitive diagnosis, a lip biopsy to examine salivary glands may be recommended, as well as tests to measure tear production (Schirmer test) and saliva production (sialometry) to assess gland function 1. It is crucial to note that Sjögren's syndrome is an autoimmune disorder affecting moisture-producing glands, and laboratory findings help differentiate it from other conditions with similar symptoms like dry eyes and dry mouth 1.
From the Research
Labs to Test for Sjögren's Syndrome
To diagnose Sjögren's syndrome, several laboratory tests can be used, including:
- Erythrocyte sedimentation rate (ESR) 2, 3, 4
- C-reactive protein (CRP) 5, 3, 4
- Plasma viscosity 3
- Fibrinogen 3
- Immunoglobulins (IgG) 3, 4
- Vitamin D levels 2
- Complete blood count (CBC) to check for cytopenia 4
- Gamma globulin levels 4
Laboratory Abnormalities
Some common laboratory abnormalities found in patients with Sjögren's syndrome include:
- Low vitamin D levels 2
- Elevated ESR 2, 3, 4
- Elevated CRP 5, 3, 4
- High plasma viscosity 3
- Elevated fibrinogen 3
- Elevated IgG levels 3, 4
- Cytopenia 4
- High gamma globulin levels 4
Diagnostic Approach
A diagnostic approach to Sjögren's syndrome may involve:
- Clinical evaluation for symptoms of dryness, asthenia-polyalgia syndrome, and systemic organ-specific manifestations 4
- Physical examination to check for parotid gland enlargement, skin lesions, respiratory crackles, arthritis, and neurological deficits 4
- Ultrasonography of the parotid glands 4
- Laboratory tests to check for laboratory abnormalities associated with Sjögren's syndrome 2, 5, 3, 4