Total Serum Calcium Level Is Negatively Correlated With Systemic Lupus Erythematosus Activity

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease and hypocomplementemia signifies disease activity. Several studies have shown that calcium may help maintain optimum function of immune system and metabolism in SLE. The aim of our study was to analyze the relationship between total serum calcium level and SLE activity. A total of 66 patients with SLE and 214 healthy controls were included in this study. Our results showed lower serum levels of calcium ( P < .001), complement C3 ( P < .001), complement C4 ( P < .001), and albumin ( P < .001) in patients with SLE. A negative correlation was found between serum calcium level and systemic lupus erythematosus disease activity index (SLEDAI) rating ( r = −0.394, P = .001). Additionally, serum level of calcium was positively correlated with serum complement C3 level ( r = 0.366, P = .003) in patients with SLE, while no such correlation was found between serum calcium level and complement C4 ( r = −0.190, P = .126). Likewise, patients with SLE with normal serum calcium level showed higher complement C3 level ( P < .01) than that of patients with low serum calcium level. Overall, the results displayed that patients with SLE have lower serum calcium level compared to healthy controls, and the serum calcium level is positively correlated with SLEDAI rating and serum complement C3 level in patients with SLE. In conclusion, the total serum calcium level is negatively correlated with SLE disease activity.