Background It is known that in ankylosing spondylitis (AS) there is a decrease in the level of vitamin D in blood serum. Its status in these patients can be determined by both exogenous (deficiencies in the diet of products that are its main sources) and endogenous (ecological problems, urbanization, seasonality) factors. In addition, the availability of vitamin D in this cohort of patients can be determined by the course of the disease. In particular, the role of vitamin D in suppressing the proliferation of T-cells and reducing the production of interleukin-2, interferon-γ, tumor necrosis factor-α, etc. is well-known. The frequency of vitamin D deficiency in the Ukrainian population of patients with AS is unknown, and the study of the relationship between vitamin D and disease activity and seasonality is also worthy of attention.

Objectives To determine vitamin D availability in men with AS and to assess its relationship with seasonality and activity of the disease.

Methods 81 men with AS were examined with an average age of 41,0±0,1 years and duration of the disease of 9,0±0,6 years. The diagnosis of AS was made according to the modified New York criteria (1984) and the ASAS criteria (2009). Seasonal measurements of vitamin D content in blood serum were carried out in the autumn-summer and winter-spring periods. Disease activity was determined on the basis of BASDAI and ASDAS-CRB indices.

Results In men with AS, vitamin D deficiency was detected in 35 (43,2%) people, an insufficient level in 25 (30,9%) cases, and in 21 (25,9%) patients, it was within the normal range. In the control group, optimal levels of vitamin D wer.e.

found in 7 (30,4%) examined patients, 9 (39,2%) patients showed insufficiency and 7 (30,4%) patients had vitamin D deficiency. It is shown that the share of people with vitamin D deficiency is the highest in the spring period (61,8%), and the winter and summer periods did not significantly affect vitamin D availability.

Vitamin levels were also closely associated with high activity of the inflammatory process. In particular, in the group of patients with a high degree of activity (BASDAI > 4 points), vitamin D deficiency was detected in 52,6% of people, which is 2,5 times higher than in the group of patients with moderate activity of AS (20,8%). Similar regularities were found according to the ASDAS index. In addition, it is the activity of the inflammatory process that is key in the occurrence of vitamin D deficiency, since regardless of the season (winter/summer), reliable correlations are established between the level of the vitamin on the one hand and the activity according to ASDAS and BASDAI on the other hand (r = -0,30; -0,27 p<0,05).

Conclusion Vitamin D deficiency occurs with a high frequency (43,2%) in men suffering from AS. Despite the fact that there are seasonal fluctuations in vitamin D levels, its status is determined precisely by the activity of the inflammatory process.

REFERENCES: NIL.

Acknowledgements: NIL.

Disclosure of Interests None Declared.