Background: Systemic lupus erythematosus (SLE) is considered an autoimmune disease that can affect many organs in the body with various clinical manifestations and different severity levels.
Objective: This work aimed to assess the level of vitamin D in the serum of patients with and without lupus nephritis and its association with disease activity, clinical and laboratory findings.
Methods: This cross-sectional study included 150 participants divided into 3 groups: Group 1 (LN group) included 50 SLE cases with lupus nephritis, group II (SLE group) contained 50 SLE cases without lupus nephritis and group III (control group) consisted of 50 healthy and sex-matched subjects. All cases were subjected to assessment of the disease activity by SLE Disease Activity Index 2000 (SLEDAI), renal SLE Disease Activity Index (rSLEDAI) and laboratory investigations [complete blood count (CBC), C- reactive protein (CRP), ESR, anti-ds-DNA, ANA, C3 and C4 concentration, urine analysis, 24-hours' protein in the urine, serum creatinine and serum 25(OH) vitamin D level].
Results: There was a significant difference between the 3 studied groups regarding 25(OH) D where the lowest level was in the LN group (p-value < 0.001). In LN and SLE groups there was a significant relation between serum 25(OH) D titre and SLEDAI (p-value.36, 0.011 respectively). Also, regression analysis test revealed that there was a significant association between 25 (OH) D and HB, WBCs, PLT, Anti-ds DNA, C3, C4, SLEDAI, and renal SLEDAI in LN and SLE groups.Low vitamin D titre showed high frequency in patients with SLE and was more frequent in SLE with lupus nephritis in all grades of low vitamin D titre (Insufficient, Deficient and sever).
Conclusions: There was a significant relation between low vitamin D titre and high and very high disease activity in patients with lupus nephritis.