Table 2. Difference of β2-MG in viral and bacterial infections.

Variable	N	β2-microglobulin (mg/L)	P value
Bacterial URTI	36	1.92 ± 0.48	reference
Viral URTI	197	2.91 ± 0.65	<0.001
Exanthem subitum	58	4.19 ± 0.90	<0.001

Notes.

URTI, upper respiratory tract infection