The TK1 protein levels in sera from patients with different hematological malignancies (n = 100: range 0.2 to 48.5 ng/mL, mean±SD = 3.05±8.65 ng/mL; Median = 0.48) were significantly higher compared with blood donors (P<0.0001, Fig 6A). Here, TK1 is linked to hematologic disorder.