Our study demonstrates that elevated serum D‐2HG (>588 ng/mL), total 2HG (>623 ng/mL), and the D/L ratio (>2.33) are highly sensitive and specific biomarkers (91%–94% specificity at 100% sensitivity) of IDH mutation in AML at diagnosis. The gene discussed is IDH2; the disease is acute myeloid leukemia.