Blood tests revealed the following: white blood cell (WBC) count, 8600 cells per μL; platelet count, 36.5 × 104 cells per μL; creatinine (Cr), 0.30 mg/dL; C-reactive protein (CRP), 1.36 mg/dL (normal, < 0.5 mg/dL); AST, 23 IU/L (normal, 10–40 IU/L); ALT, 13 IU/L (normal, 5–40 IU/L); d-dimer, 20.3 μg/mL (normal, < 1.0 μg/dL); mycoplasma pneumonia IgM, < 40 times (normal). Here, CRP is linked to Mycoplasma pneumoniae pneumonia.