Serum leucine-rich alpha-2 glycoprotein levels in rheumatoid arthritis and spondyloarthritis: A promising biomarker

Background: In the early stages of the disease, some of the signs and symptoms of joint inflammation in rheumatoid arthritis (RA) may resemble that of spondyloarthritis (SpA). An examination that can help distinguish RA and SpA is warranted. One such examination is the measurement of serum leucine-rich alpha-2 glycoprotein (LRG) levels. This study aimed to measure serum LRG levels in RA and SpA patients and determine the role of LRG in the diagnosis of RA and SpA. Methods: This is a cross-sectional study consisting of 26 RA subjects and 26 SpA subjects. The SpA subjects were further grouped into ankylosing spondylitis (AS), psoriatic arthritis (PsA), and peripheral SpA. Measurement of serum LRG levels were conducted using ELISA. Difference between LRG levels of the two groups were compared using the Mann-Whitney test. Results: LRG levels were elevated in 76.9% and 84.6% of subjects with RA and SpA, respectively. The median LRG levels were higher in RA subjects (77.03 (27.16–107.73)) than SpA (68.67 (33.15–115.18)). There was no significant difference in LRG levels in RA and SpA subjects (p = .442). The RA and PsA group were predominated by diseases of moderate activity, 88.5% and 58.3%, respectively. In comparison, AS was dominated by high disease activity (85.7%). The highest median LRG levels in AR and SpA subjects were in new-onset patients (82.21 vs. 72.25 µg/dL). Conclusions: There was no significant difference in LRG levels between RA and SpA subjects. The role of LRG in the diagnosis of RA and SpA remains to be determined in future studies.