Comparison of vitamin D profile between patients with inflammatory and non-inflammatory rheumatic diseases

Vitamin D is synthesized in the skin in the presence of sunlight and then metabolized into an active metabolic form in the liver, kidney and peripheral immune/inflammatory cells. Active metabolite of vitamin D [1,25(OH)2D] is important for bone metabolism and function of neuromuscular system. The deficiency of this hormone is mainly associated with osteoporosis in adults and rickets in pediatric population. Also, the deficiency of this hormone is observed to be associated with different forms of non-inflammatory chronic pain conditions (1-4). One of the types of non-inflammatory chronic pain is persistent nonspecific musculoskeletal pain, such as non-inflammatory unexplained arthralgia or myalgia, which is seen frequently in rheumatology clinics. In this type of chronic pain conditions, reaching a precise diagnosis and decision on an effective treatment can be quite challenging for the clinician. Vitamin D is also known to have a role in the regulation of immune system. Active metabolite of vitamin D appears to have an immunosuppressive effect and to play a role in the autoimmune diseases (5). It is not so evident that the deficiency of vitamin D has causality for rheumatic diseases, whereas the prevalence is claimed to be high (6-8). Several surveys indicated that patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS), scleroderma, polymyositis, dermatomyositis and systemic lupus DOI: 10.4274/gulhane.galenos.2020.1089 ORIGINAL ARTICLE