The Effect of Methotrexate on Serum Levels of Trace/Mineral Elements in Patients with Psoriatic Arthritis

Psoriatic arthritis is a type of inflammatory arthritis that occurs in some patients with psoriasis. Clinically, low-dose methotrexate was used to treat psoriatic arthritis as a first-line agent. However, the pathogenesis of psoriatic arthritis and the mechanism of methotrexate treating psoriatic arthritis remained unclear. In recent years, a variety of side effects associated with methotrexate have been reported. In order to illuminate the role of trace/mineral elements in the pathogenesis of psoriatic arthritis and the side effect of low-dose methotrexate on blood cells and trace/mineral elements in patients with psoriatic arthritis, 37 psoriatic arthritis patients and healthy 50 people with similar age and gender were enrolled in this study. The blood cells, serum trace/mineral elements, liver function, and kidney function were determined. The results revealed that the level of serum zinc was significantly lower and copper was significantly higher in psoriatic arthritis patients in comparison with healthy control. After giving patients methotrexate intravenously (15 mg weekly), their serum zinc was significantly increased, and copper was significantly decreased with symptoms relieved. Our study provided the evidence that low zinc and high copper might be associated with the pathogenesis of psoriatic arthritis, and the possible mechanism of methotrexate treating psoriatic arthritis was through elevating zinc and reducing copper in serum. Moreover, we demonstrated that low-dose methotrexate could induce liver damage to psoriatic arthritis patients.