AST and ALT Levels of 300 in Dengue Fever
AST and ALT levels of 300 IU/L are not commonly found in dengue fever, though liver enzyme elevations are frequent. Most dengue patients show mild to moderate transaminase elevations, with severe elevations (>1000 IU/L) occurring in only about 1% of cases.
Typical Liver Enzyme Patterns in Dengue
Classic Dengue Fever (DF)
- AST levels average 84.5 ± 42.4 IU/L in classic dengue fever, representing mild to moderate elevation 1
- ALT levels average 59.9 ± 31.3 IU/L in classic dengue fever, consistently lower than AST 1
- The AST:ALT ratio is typically 1.8:1 in dengue infection, with AST rising far greater than ALT 1, 2
- Approximately 88% of adult dengue patients show elevated AST, while 69% show elevated ALT 2
Dengue Hemorrhagic Fever (DHF)
- AST levels average 507 ± 106.8 IU/L in DHF, significantly higher than classic dengue but still below 1000 IU/L in most cases 1
- ALT levels average 234 ± 30.6 IU/L in DHF, representing moderate elevation 1
- 100% of DHF grade I patients show AST elevations, with 83.3% showing ALT elevations 3
- All DHF grade II patients demonstrate both AST and ALT elevations 3
Severe Elevations (≥1000 IU/L)
Only 1% of dengue patients (7 out of 690) reached AST or ALT ≥1000 IU/L in a large Singapore cohort, and none developed acute liver failure 4. This threshold is used in WHO 2009 criteria to define severe dengue, but it represents an uncommon presentation 4.
Three patients with severe dengue showed AST and ALT >1000 IU/L in the absence of fluid leakage or hematocrit rise, suggesting direct viral hepatocyte damage rather than hypoxic injury 5.
Clinical Significance of 300 IU/L Elevation
Transaminase levels of 300 IU/L fall in the moderate elevation range, between the typical classic dengue levels (~85 IU/L) and severe dengue levels (>1000 IU/L) 1, 4.
This level of elevation would be more consistent with DHF than classic dengue fever, as DHF shows significantly higher aminotransferase levels compared to classic dengue 1.
Peak AST levels typically occur on day 6 of illness, approximately 24 hours after peak viremia and 24 hours before maximum fluid leakage 5.
Discriminatory Value
AST and ALT values show significant overlap between dengue fever and DHF, with poor discriminatory ability (AST area under ROC curve = 0.56 for DF vs DHF) 4.
Although aminotransferase levels increase with dengue severity, they cannot reliably distinguish between non-severe and severe dengue (AST area under ROC curve = 0.62) 4.
Important Clinical Caveats
AST elevation is more prominent than ALT in dengue, unlike typical viral hepatitis where ALT predominates, making the AST:ALT ratio >1 characteristic of dengue hepatitis 1, 2.
Liver function tests performed before day 5-6 of illness may underestimate the extent of liver involvement, as peak elevations occur later in the disease course 5.
High-level ALT during the febrile stage shows association with shock, making it a potentially useful prognostic marker 2.
Patients with nausea/vomiting, petechiae, or fever duration >7 days more frequently have abnormal transaminases, suggesting these clinical features correlate with hepatic involvement 2.