Serum beta-2 microglobulin level is elevated in patients with acute coronary syndrome

Abstract

Background Beta-2 microglobulin (B2M) is a marker of renal dysfunction and immune activation. We previously reported that serum B2M is related to age, renal function, cardiovascular and all-cause mortality in Americans. Acute coronary syndrome (ACS) is a common cause of hospital admission and cardiovascular mortality. We tested the hypothesis that the serum level of B2M is elevated in ACS in a prospective study. Methods We recruited 167 Chinese patients (118 men and 49 women; mean age±SD, 64±13 years), of whom 88 had ACS and 79 were controls matched for age and sex. Serum B2M was measured in an accredited laboratory using a latex-enhanced immunoassay (intra-assay coefficient of variation 3.4%). Results In our patients, the serum B2M level (mean±SE) was 2.27±0.12 µg/mL. Because the upper reference level of serum B2M in our laboratory is 1.42 µg/mL, only 24 subjects (14%) had a serum B2M within the reference range. Serum B2M levels (mean±SE) were 2.52±0.21 in ACS patients and 1.99±0.06 µg/mL in controls (p=0.02). There was no significant correlation between serum B2M and troponin level. Serum B2M correlated with serum creatinine (ρ=0.62, p<0.001), age (Spearman’s ρ=0.52, p<0.001) and male gender (ρ=0.19, p=0.01). Conclusions Serum B2M level is increased in ACS patients. It is also related to age and gender, and the serum level of creatinine but not troponin. Our study shows for the first time that serum B2M is a cardiovascular risk marker in Chinese as it is in Americans. B2M is an established prognostic marker in multiple myeloma and so the test is widely available. A prospective study with long follow-up is warranted to evaluate B2M as a prognostic marker after ACS.