Copper-to-Zinc Ratio as an Inflammatory Marker in Serum of Iraqi Patients with Axial Spondyloarthritis

Abstract

Axial spondyloarthritis (axSpA) is a chronic rheumatic inflammatory disease affecting mainly the spine and sacroiliac joints. Since the copper-to-zinc ratio (Cu/Zn) indicates an inflammatory response, the change in ratio is expected to correlate with axSpA. This study compared levels of Cu/Zn in the serum of axSpA patients. Serum samples were obtained from 53 patients with axSpA divided according to biological treatment into cohorts A and B, and 28 healthy control as cohort C. Serum levels of Cu and Zn were determined first by a fully automated chemistry analyzer TC-Matrix Plus, then the ratio was obtained. The elevated serum Cu concentration means of cohort B (189.32 ± 13.808 µg/dL) compared to cohort A (168.85 ± 7.244 µg/dL) and cohort C (155.68 ± 3.707 µg/dL) with 0.029 p-values. Reduced Zn concentration means of cohort B (79.74 ± 4.344 µg/dL) compared to cohort A (91.26 ± 4.159 µg/dL) and cohort C (100.93 ± 6.161 µg/dL) with 0.031 p-values. The Cu/Zn mean of cohort B was (2.54 ± 0.25) compared to the Cu/Zn mean of cohort A (1.968 ± 0.125) and cohort C (1.679 ± 0.104) with 0.002 p-values. Due to the results suggesting that the differences between cohorts were associated with inflammatory responses since there was a similar change in ESR levels; however, the differences between cohorts A and B are due to the anti-inflammatory therapy (TNF inhibitor) that cohort A was treated with. Keywords: Axial spondyloarthritis; copper-to-zinc ratio; copper; zinc; inflammation.