Table 1 Diagnostic Criteria of HLH as defined by the HLH-2004 Criteria

Fever ≥38.5 °C

+

+

Splenomegaly

–

–

Hemoglobin < 9 g/dL^a

–

+

Platelets < 100,000 microL^a

+

+

Absolute Neutrophil Count < 1000/microL^a

–

–

Hypertriglyceridemia: Fasting Triglycerides > 265 mg/dL

+

+

Hypofibrinogenemia: Fibrinogen < 150 mg/dL

–

+

Hemophagocytosis in bone marrow, spleen, lymph node or liver

+

–

Low or absent NK cell activity

n/a

n/a

Ferritin > 500 ng/mL

+

+

Elevated soluble CD25 (soluble IL-2 receptor alpha) two standard deviations above age-adjusted laboratory-specific norms

+

–