Haematocrit Levels for Dengue According to Malaysian CPG
According to the Malaysian Clinical Practice Guidelines for Dengue Infection in Adults, a rise in haematocrit of ≥20% from baseline (or a haematocrit ≥40% in women and ≥46% in men when baseline is unknown) is considered a warning sign for severe dengue and indicates plasma leakage. 1
Warning Sign Criteria
The Malaysian CPG identifies haematocrit rise with rapid platelet drop as a critical warning sign that significantly predicts severe dengue outcomes:
- A ≥20% increase in haematocrit from baseline concurrent with rapidly falling platelet count is strongly associated with progression to severe dengue (adjusted OR: 2.74) 2
- This combination of rising haematocrit with decreasing platelets has the highest predictive value (OR = 5.13) among all warning signs for identifying severe dengue 3
Baseline Haematocrit Thresholds
When baseline values are unavailable, the Malaysian guidelines use these cut-off levels to indicate plasma leakage:
These thresholds have been validated specifically for the Malaysian population 1
Clinical Significance for Monitoring
- Daily complete blood count monitoring is essential to track both haematocrit and platelet trends, allowing early detection of hemoconcentration 4, 5
- High baseline haematocrit levels are independently associated with bleeding tendencies and progression to dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) 1
- The presence of haematocrit rise with rapid platelet drop should trigger immediate hospitalization for closer monitoring during the critical phase (typically days 3-7 of illness) 4, 6
Common Pitfalls to Avoid
- Do not rely on a single haematocrit measurement in isolation—serial measurements are required to detect the critical ≥20% rise that indicates plasma leakage 4
- Failing to recognize the critical phase when haematocrit rises can lead to delayed intervention, as plasma leakage can rapidly progress to shock 6
- A normal initial haematocrit does not exclude severe disease; continued monitoring throughout the febrile period is mandatory 4