Dry mouth and dry eyes (sicca symptoms) are key diagnostic symptoms in Sjögren syndrome, yet are often overlooked as unimportant by both patients and doctors (Brito-Zerón 2016). A study that examined data from 6,110 people with primary Sjögren syndrome found that 98% had at least one of these symptoms at the time of diagnosis and 89% had both (Brito Zeron 2015). Therefore, the presence of dry eyes or dry mouth, and especially both, warrants further investigation into possible Sjögren syndrome (Brito-Zerón 2016).
According to the American College of Rheumatology and the European League Against Rheumatism, the most useful tests in diagnosing primary Sjögren syndrome are (Shiboski 2017):
- Salivary gland biopsy. Signs of inflammation and white blood cells in salivary gland tissues of the lip mucosa are considered indicative of Sjögren syndrome, but are not always present (Shiboski 2012).
- Anti-SSA/Ro antibodies. The presence of these antibodies is a key indicator of Sjögren syndrome; however, they can also be seen in patients with other autoimmune diseases (Brito-Zerón 2016).
- Ocular staining. Eye drops that temporarily stain the surface of the eye allow visualization of changes to the corneal surface associated with excessive dryness and an insufficient tear film (JHM 2017). Dry eyes may be seen in a range of autoimmune and other conditions, including Sjögren syndrome (Generali 2015).
- Schirmer’s test. This test measures tear secretion in patients with dry eyes using absorbent strips that are inserted under the lower eyelids (Mayo Clinic 2014).
- Unstimulated whole saliva flow rate. One of the simplest tests involves collection and measurement of saliva produced over several minutes. While the normal rate of salivary flow is 0.3–0.4 mL/minute, a rate of <0.1 mL/minute indicates hyposalivation, possibly, but not necessarily, associated with Sjögren syndrome (Aoun 2016).
The most recent guidelines stipulate that a diagnosis of primary Sjögren syndrome requires both a positive biopsy and a positive anti-SSA test, or one of these along with abnormal results from at least one of the other three tests on this list (Shiboski 2017). Clinical exam and laboratory tests assessing possible systemic manifestations, such as neurological, joint, blood, and skin disorders, can be helpful in identifying early Sjögren syndrome in patients without typical sicca symptoms (Brito-Zerón 2016). In addition, appropriate workup includes investigations for Sjögren complications, such as dental cavities, oral yeast infection, other autoimmune diseases, lymphoma, and thyroid, liver, lung, and kidney diseases (Shiboski 2012; Mayo Clinic 2014).