Objective:

To evaluate serum beta-2 microglobulin (β2M) as a diagnostic biomarker for acute primary Epstein–Barr virus (EBV) infection in children and to compare serum vitamin D3 levels between EBV-infected children and those with viral upper respiratory tract infections.

Approach:

• Study Design: A retrospective cross-sectional study involving 129 children with acute primary EBV infection and 130 control children with viral upper respiratory tract infections.
• Data Analysis: Comparison of age, gender, laboratory indicators, and correlation analysis between β2M and serum EBV-DNA concentration using Pearson's correlation.
• ROC Curve Analysis: Receiver operating characteristic (ROC) curve was drawn to calculate the threshold and area under the curve (AUC) of β2M for diagnosing EBV infection.

Key Findings:

• White blood cell count, serum lactate dehydrogenase, and alanine aminotransferase levels were significantly higher in the EBV group (P < 0.0001).
• Serum β2M levels were significantly higher in the EBV group than in the control group (P < 0.001).
• Serum vitamin D3 levels were significantly lower in the EBV group (P < 0.001).
• A positive correlation was found between serum β2M levels and serum EBV-DNA load (r = 0.469, P < 0.01).
• The AUC of serum β2M for diagnosing EBV infection was 0.907, with an optimal threshold of 3.3 mg/L, specificity of 62.1%, and sensitivity of 90.8%.

Interpretation:

Serum β2M levels are significantly increased during primary EBV infection in children.

Limitations:

• The study is retrospective and conducted at a single center, which may limit generalizability.
• The sample size may not be sufficient to fully establish β2M as a definitive diagnostic tool.

Conclusion:

Serum β2M is associated with primary EBV infection in children, while serum vitamin D3 levels are significantly reduced in this population.