Table 1. Clinical and laboratory findings included in the adapted H-score and HLH-2004 guidelines.

* Diagnosis requires either the presence of molecular diagnosis or the presence of five out of eight criteria.

** A scoring cutoff of 169 is used to diagnose HLH.

HLH: hemophagocytic lymphohistiocytosis; NK: natural killer; IL-2: interleukin-2.

Clinical/laboratory finding	HLH-2004*	H-score**
Fever	>38.5°C	<38.4: 0 points
		38.4-39.4: 33 points
		>39.4: 49 points
Organomegaly	Splenomegaly	Absent: 0 points
		Hepatomegaly OR splenomegaly: 23 points
		Hepatomegaly and splenomegaly: 38 points
Cytopenia	≥2 of 3 lineages in peripheral blood	One lineage: 0 points
Hemoglobin < 9 g/dL		Two lineages: 24 points
Platelet count < 100*10⁹/L		Three lineages: 34 points
Neutrophils < 1.0*10⁹/L
Fibrinogen	<1.5 g/L	>2.5 g/L: 0 points
		≤2.5 g/L: 30 points
Triglycerides	>3.0 mmol/L (>265mg/dL)	<1.5 mmol/L: 0 points
		1.5-4 mmol/L: 44 points
		>4 mmol/L: 64 points
Ferritin	>500 µg/L	<2,000 µg/L:0 points
		2,000-6,000 µg/L: 35 points
		>6,000 µg/L: 50 points
Hemophagocytosis in bone marrow	Hemophagocytosis in bone marrow liver, spleen, lymph nodes, or other tissues	Absent: 0 points
		Present: 35 points
NK cells activity	Low or absent	N/A
Soluble CD25 (soluble IL-2 receptor)	≥2,400 U/mL	N/A
Known underlying immunosuppression	N/A	Absent: 0 points
		Present: 18 points
Serum aspartate aminotransferase (AST)	N/A	<30 U/L: 0 points
		>30 U/L: 19 points