Asashima H, Inokuma S, Onoda M et al.Cut-off levels of salivary beta2-microglobulin and sodium differentiating patients with Sjögren's syndrome from those without it and healthy controls.” Clin Exp Rheumatol. (2013) Jun 26. [Epub ahead of print] PMID: 23806216
Levels of the biomarker β2 microglobulin (β2MG), a polypeptide found in saliva and serum, may be useful together with sodium (Na+) in identifying patients with Sjögren syndrome (SS), according to Japanese researchers.
Previous studies have shown β2MG in serum to be a marker for diagnosing and assessing disease activity in SS, and numerous studies have examined other candidate salivary biomarkers for the condition. But these authors say the diagnostic utility of β2MG and Na+ from saliva is not yet established.
Rheumatologists at the Japanese Red Cross Medical Center in Tokyo examined β2MG, Na+, Cl-, and potassium in whole unstimulated saliva from 71 primary Sjögren's (pSS) patients (the majority women with a median age of 60), 50 patients with secondary SS (sSS, also predominantly female), 54 people with connective tissue diseases unrelated to Sjögren syndrome, and 75 healthy controls.
In the SS group (both pSS and sSS), salivary levels of β2MG, Na+, and Cl- were significantly higher than in samples from the others. The cut-off levels that appear to differentiate SS patients from unaffected individuals are 2.3 mg/L for β MG and 23 mEq/L for Na+.
The hunt continues for other signs of the disease to be found in saliva. A multicenter observational trial of numerous salivary biomarkers for Sjögren syndrome sponsored by University of California Los Angeles, launched earlier this year, has not yet begun recruiting patients.