Evaluation of Plasma Vitamin C Levels in a Population of Chronic Rheumatism in Immuno-Rheumatology

Evaluation of Plasma Vitamin C Levels in a Population of Chronic Rheumatism in Immuno-Rheumatology

Scurvy is an almost forgotten carential pathology, caused by a deep vitamin C (or ascorbic acid) deficiency, a priori exceptional in industrialized countries. According to the French National Authority for Health standards, hypovitaminosis C is defined as a plasma vitamin C level of less than 23 μmol/L. This deficiency would affect 5 to 10% of the general population in industrialized countries and from 17% (clinical scurvy) to 47% (biological hypovitaminosis C) of vulnerable populations (malnutrition, hospitalized patients...). Vitamin C is essential for collagen synthesis. It plays a cofactor role in the synthesis of catecholamines precursors and takes action in synthesis of certain amino acids.

In rheumatology, pain is a recurring reason for consultation. In a context of treated chronic inflammatory rheumatism (RIC), while most of patients seem in remission or in reduced activity of their disease, all real-life studies show that 30 to 40% of them complain of residual pain, 70% of chronic fatigue and 20-25% of symptoms similar to secondary fibromyalgia. Currently, authors suggest the interest of vitamin C analgesic properties, especially in musculoskeletal pain, due to the role of ascorbic acid in neurotransmitters. Vitamin C would act as a cofactor for a family of biosynthetic and regulatory metalloenzymes. Thus, the authors suggest the potential of vitamin C in an analgesic mechanism involving the biosynthesis of opioid peptides.

Inclusion Criteria:

• patient over 18 years-old,
• followed for chronic inflammatory rheumatism (RIC): spondylo-arthritis (including spondylitis and psoriatic rheumatism) and lupus,
• with RIC in remission or low activity definec according to the following criteria: Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) criteria and Bath Ankylosing Spondylitis Fonctional Index (BASFI) questionnaire for spondylitis and psoriatic rheumatism, Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) 2K score for lupus,
• having given written consent after written and oral information,
• member of the social security system,
• basic treatment for the disease not modified for at least 6 months, without modification at baseline
• persistence of painful complaints not objectively explained by his RIC.

Exclusion Criteria:

• pregnant or nursing patient,
• patient protected by law or under guardianship or curatorship, or not able to participate in a clinical trial under L.1121-16 article of French Public Health Regulations,
• patient participating in or having participated in another drug clinical trial in the month prior to inclusion.