Diagnostic Criteria for HLH, Diagnosis Requires 5 of the Following 8 Findings

Diagnostic Criteria
Fever of ≥38.5°C
Peripheral blood cytopenia with at least 2 of the following: hemoglobin of <9 g/dL (for infants <4 wk old, hemoglobin of <10 g/dL), platelets of <100 000/µL, and an absolute neutrophil count of <1000/µL
Hypertriglyceridemia (fasting triglycerides: >265 mg/dL) and/or hypofibrinogenemia (fibrinogen: <150 mg/dL)
Hemophagocytosis in bone marrow, spleen, lymph node, or liver
Low or absent NK cell activity
Ferritin >500 ng/mL (ferritin >3000 ng/mL is more indicative of HLH)
Elevated soluble IL-2 receptor α of 2 SDs above age-adjusted, laboratory-specific norms
  • Adapted from Henter J-I, Horne A, Arico M, et al. HLH-2004: Diagnostic and therapeutic guidelines for hemophagocytic lymphohistiocytosis. Pediatr. Blood Cancer. 2007;48(2):124–131.