Selenium deficiency is associated with polyneuropathy in primary Sjögren's syndrome

Selenium plays an important role in the regulation of the immune system. Selenium deficiency is associated with Hashimoto's thyroiditis, a common comorbidity in primary Sjögren's syndrome (pSS). Therefore we aimed to identify whether or not selenium deficiency is also associated with pSS.

107 consecutive female patients with pSS and, as a control, 59 female patients with axial spondyloarthritis were recruited. Later, 11 male pSS patients, 5 of these suffering from polyneuropathy, and 15 male axSpA patients were additionally recruited in order to confirm the results from the female patients. All patients were consulted about their diet and food intolerances and their plasma selenium concentrations were analyzed. Current and previous extraglandular manifestations of pSS were recorded. Patients complaining of misperceptions and tingling paraesthesia underwent measurement of nerve conduction velocity. The proportion of patients and controls with a selenium deficiency was compared using Fisher's exact test.

The proportion of female pSS patients with a low selenium concentration <0.63 μmol/L (22.4%) was significantly higher than of the controls (1.7%) (p < 0.001). Within the group of female patients with pSS, selenium deficiency was significantly associated with the presence of polyneuropathy (45.8% with vs 14.5% without polyneuropathy, p = 0.003) and particularly polyneuropathy with motor nerve involvement measured by nerve conduction velocity (41.7% with vs 10.8% without motor neuropathy, p = 0.001). The mean selenium concentrations of the 5 male pSS patients with polyneuropathy were significantly lower compared to the 6 pSS patients without polyneuropathy and to the 15 male axSpA controls.

PSS and in particular its complication polyneuropathy is associated with selenium deficiency. Measurement of the selenium concentration in blood is advisable in patients with pSS and in particular in the subset of patients with polyneuropathy. Substitution of selenium may be a possible therapy of polyneuropathy associated with pSS.