An Observational Study on the Comparison of Vitamin D Serum Values between Rheumatoid Arthritis and Lupus Populations

This study aims to compare VitD serum values in lupus (SLE) and Rheumatoid Arthritis (RA) in the
geographical region of northeastern Iran. Lupus and RA Patients were selected with various disease
activity levels. All the patients received an equal amount of VitD supplementation and were selected
by the same inclusion and exclusion criteria. VitD serum values were measured by a commercial
ELISA kit. Data were analyzed in SPSS-15. A total of 148 SLE and 156 RA patients were studied.
VitD serum levels were 66.54±41.2 nmol/l in the SLE group and 83.74±46.45 nmol/l in the RA group.
Statistical analysis showed that VitD serum levels were lower in lupus patients than RA ones
(p=0.006). Lower VitD values in lupus patients compared with RA ones may stem from intestinal
malabsorption, higher doses of corticosteroid therapy, renal involvement and proteinuria, different
polymorphisms of VitD receptors, and more sun protection strategies in lupus patients.