New research out of the journal Rheumatology International has found that people newly diagnosed with Sjögren’s syndrome are more likely to be deficient in vitamin D compared to those that suffer similar symptoms but don’t suffer from Sjögren’s syndrome.
Sjögren’s syndrome is an autoimmune disease. Vitamin D deficiency has been linked to an assortment of autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus (often just called lupus), antiphospholipid syndrome, type I diabetes, multiple sclerosis and systemic sclerosis. The degree to which vitamin D deficiency plays a causative or associative role in these diseases is not well understood at this time.
Past research has found that people with Sjögren’s syndrome have low vitamin D levels. However, it’s not clear if vitamin D plays a role in the disease, or if people with Sjögren’s syndrome simply do not get enough sun exposure.
Sjögren’s syndrome is characterized by a progressive hypofunction of the salivary and lacrimal glands (lacrimal glands are responsible for helping your eyes tear up). In consequence, this creates dry-eyes and dry-mouth. Some complications of this condition includes increased dental caries and blurred vision.
In the present study, researchers wanted to look at recently diagnosed Sjögren’s syndrome, to see what the vitamin D status of people who have just recently developed the disease. The advantage to this approach is to better rule out the possibility that the disease is causing vitamin D deficiency (though the study is not designed to conclusively rule this out).
The researchers took a look at 76 consecutive patients referred to their rheumatology unit after symptoms of dry eyes and mouth. Doctors made a diagnosis of Sjögren’s syndrome if they met international classification criteria for the disease (called AECG criteria). They found that 30 patients met criteria for Sjögren’s syndrome while the other 46 did not. The 46 that did not have Sjögren’s syndrome made up the study’s control group.
The researchers looked at many markers in both groups, including vitamin D levels. Here is what they found:
- There was no seasonal pattern to the diagnosis of Sjögren’s syndrome.
- There were differences in the groups’ vitamin D levels. Overall, 53% of patients with Sjögren’s syndrome had levels less than 20 ng/ml, while 48% of the controls had levels less than 20 ng/ml.
- Twenty-three percent of Sjögren’s syndrome patients had severe vitamin D deficiency (less than 10 ng/ml) compared to 17.4% in the control group.
- The researchers observed a correlation between vitamin D levels and white cell count (r = 0.29, p = 0.01). Leukopenia, a condition of low white blood cell account, was observed in 40% of people with severe vitamin D deficiency, compared to just 11% of people without severe deficiency.
- However, vitamin D status did not correlate with Sjögren’s syndrome severity.
The researchers concluded,
“Although the results of this study support the evidence of reduced vitamin D levels in Sjögren’s syndrome at the earliest stages, the impact of vitamin D deficiency on Sjögren’s syndrome pathogenesis and clinical presentation remains a matter of debate. Considering the relatively small number of patients enrolled in our study, larger studies are mandatory before drawing any firm conclusion on the role of hypovitaminosis D in Sjögren’s syndrome pathogenesis. It is likely that the assessment of vitamin D might be useful especially in specific subsets of Sjögren’s syndrome (i.e., in patients with leukocytopenia) who could benefit from a supplementation.”