Metallothionein-1 Serum Level in Ankylosing Spondylitis Patients: Correlation with Disease Activity Ahmed A. Emerah1, Christine Beshara Shafiq1*, Asmaa A. Saad 2, Dina Said 1 1 Rheumatology and Rehabilitation department, Faculty of Medicine, Zagazig University, Zagazig, Egypt. 2 Clinical Pathology department, Faculty of Medicine, Zagazig University, Zagazig, Egypt. ABSTRACT Background: Elevated Serum Metallothionein-1 (MT-1) levels have been described in a large spectrum of acute and chronic inflammatory diseases, so measuring MT-1 levels in the serum of Ankylosing Spondylitis (AS) could provide additional information about the diseases and better long-term outcome. This work aimed to investigate the role of Serum MT-1 in evaluation of disease activity in AS patients. Methods: This is a matched case control work that was conducted on sixty individuals categorized into two equal groups, Group I: 30 patients with AS, Group II: 30 apparently healthy volunteers serving as a control group. All patients undergone clinical examination, assessment of disease activity in addition to the laboratory investigations, serum MT-1 was assessed by enzyme linked immunosorbent assay (ELISA). Results: The median of Serum MT-1 was significantly higher among the AS group (P <0.001) with Ankylosing Spondylitis Disease Activity Score C-reactive protein (ASDAS-CRP) grade (r=0.441, P=0.02), Erythrocyte Sedimentation Rate (ESR) (r=0.486, P=0.006) as well as CRP (r=0.513, P=0.004). Serum MT-1 had the highest sensitivity (93.33%) and specificity (90%) at cut-off point (23.42) among AS patients with area under the curve was (0.886) to discriminate healthy subjects from AS patients. It also had the highest sensitivity (96.3%) and specificity (66.67%) at cut-off point (40.35) among AS patients with area under the curve was (0.840) to discriminate highly active AS patients from moderately active AS patients. Conclusion: Serum Metallothionein-1 could serve as a valuable biomarker for Ankylosing Spondylitis disease activity. Keywords: Serum Metallothionein-1, Activity, Ankylosing Spondylitis.