HScore (reactive haemophagocytic syndrome)
Probability of secondary HLH in adults
- Onkopedia HLH (DGHO)
Sources last checked: 2026-10-13
HScore (reactive haemophagocytic syndrome)
Probability of secondary HLH in adults
Derived in adults outside the ICU; in critically ill patients a lower cut-off (≈ 168) performed best. Bone-marrow haemophagocytosis is not required for HLH. Not validated in children.
Interpretation
| ≤ 90 — HLH very unlikely | Probability of HLH < 1 % in the derivation study. |
|---|---|
| 91–168 — below the diagnostic cut-off | HLH not excluded; the score changes as laboratory values evolve. |
| ≥ 169 — HLH likely | Best cut-off in the derivation study: sensitivity 93 %, specificity 86 %. |
| ≥ 250 — HLH almost certain | Probability of HLH > 99 % in the derivation study. |
What is the HScore (reactive haemophagocytic syndrome)?
The HScore estimates the probability that an adult has reactive (secondary) haemophagocytic lymphohistiocytosis from nine clinical, laboratory and bone-marrow findings, with weights from 18 to 64 points (maximum 337). It was developed by Fardet and colleagues in 2014 in a French multicentre cohort of 312 adults. A cut-off of 169 gave 93 % sensitivity and 86 % specificity.
When to use it
- In adults with unexplained fever, cytopenias and very high ferritin
- When haematological malignancy, infection (e.g. EBV) or autoimmune disease is complicated by suspected hyperinflammation
- Alongside the HLH-2004 criteria to structure the diagnostic work-up
When not to use it
- In children — the HLH-2004 criteria were developed for paediatric HLH
- As the sole basis for starting HLH-directed treatment without expert input
How it is calculated
| Criterion | Points |
|---|---|
| Known underlying immunosuppression | |
| No | 0 |
| Yes | 18 |
| Maximum temperature | |
| < 38.4 °C | 0 |
| 38.4–39.4 °C | 33 |
| > 39.4 °C | 49 |
| Organomegaly | |
| None | 0 |
| Hepatomegaly or splenomegaly | 23 |
| Hepatomegaly and splenomegaly | 38 |
| Number of cytopenic lineages | |
| None or one lineage | 0 |
| Two lineages | 24 |
| Three lineages | 34 |
| Ferritin | |
| < 2000 µg/L | 0 |
| 2000–6000 µg/L | 35 |
| > 6000 µg/L | 50 |
| Triglycerides | |
| < 1.5 mmol/L | 0 |
| 1.5–4.0 mmol/L | 44 |
| > 4.0 mmol/L | 64 |
| Fibrinogen | |
| > 2.5 g/L | 0 |
| ≤ 2.5 g/L | 30 |
| AST (GOT) | |
| < 30 U/L | 0 |
| ≥ 30 U/L | 19 |
| Haemophagocytosis on bone-marrow aspirate | |
| No / not done | 0 |
| Yes | 35 |
Clinical pearls and limitations
- Derived in adults outside the ICU; in critically ill patients a lower cut-off (≈ 168) performed best. Bone-marrow haemophagocytosis is not required for HLH. Not validated in children.
- Ferritin is in µg/L (= ng/mL) and triglycerides in mmol/L; convert mg/dL by dividing by 88.5.
- Bone-marrow haemophagocytosis is neither necessary nor specific — score 0 if not done.
- Very high ferritin alone is not specific: haemolysis, transfusion, dialysis and liver failure also raise it.
- In critically ill patients, a cut-off around 168 performed best in a large ICU cohort (Knaak 2020).
Frequently asked questions
What HScore indicates HLH?
A score of 169 or more had the best balance in the derivation study (sensitivity 93 %, specificity 86 %). ≤ 90 corresponds to < 1 % probability and ≥ 250 to > 99 %.
What counts as a cytopenia in the HScore?
Haemoglobin ≤ 92 g/L, leukocytes ≤ 5.0 ×10⁹/L and platelets ≤ 110 ×10⁹/L; score by the number of lineages affected.
Is bone marrow needed to calculate the HScore?
No. If no aspirate was done, the item scores 0.
Evidence and guidelines
- Primary source: Fardet L, Galicier L, Lambotte O, et al. Development and validation of the HScore, a score for the diagnosis of reactive hemophagocytic syndrome. Arthritis Rheumatol 2014;66(9):2613-2620.
- Mehta P et al. COVID-19: consider cytokine storm syndromes and immunosuppression. Lancet 2020;395:1033-1034 (HScore points table and cytopenia definitions).
- Knaak C et al. Hemophagocytic lymphohistiocytosis in critically ill patients: diagnostic reliability of HLH-2004 criteria and HScore. Crit Care 2020;24:244.
- Onkopedia (DGHO): Hämophagozytische Lymphohistiozytose (HLH).
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