Non-Invasive Testing
Kimberly Schuster
Consider NITs when: patients with steatosis noted on imaging or for whom there is a clinical suspicion of MASLD, such as those with metabolic risk factors (e.g., HTN, HLD, T2DM, obesity) or unexplained elevations in liver chemistries
- Primary Risk Assessment:
- FIB-4 score: estimates degree of scarring and is based on age, AST, ALT, platelet count [FIB-4 = (Age x AST) / (Platelets x √ALT)]
- High negative predictive value for advanced fibrosis, making it useful to rule out high-risk disease
- Limitations:
- Less reliable in patients <35 or >65 years
- AST elevation from alcohol, acute inflammation, or other causes may falsely elevate score
- Platelet abnormalities from non-liver causes may affect accuracy
- FIB-4 score: estimates degree of scarring and is based on age, AST, ALT, platelet count [FIB-4 = (Age x AST) / (Platelets x √ALT)]
FIB-4 Score | Risk Category | Next Step |
|---|---|---|
| <1.3 | Low | Manage in primary care; reassess every 1-2 years |
| 1.3-2.67 | Intermediate | Proceed to secondary risk assessment (VCTE or ELF) |
| >2.67 | High |
Secondary Risk Assessment (FIB-4 ≥ 1.3)
- Vibration Controlled Transient Elastography (VCTE, “FibroScan”): Measures liver stiffness (LSM) in kilopascals (kPa). Increased stiffness correlates with fibrosis.
- LSM < 15kPa + Platelets>150k = Portal HTN unlikely
- LSM ≥25kPa = Portal HTN likely
- Important Caveats: VCTE may be falsely elevated in acute hepatitis, active alcohol use, cholestasis, congestive hepatopathy.
- Important Controlled Attenuation Parameter (CAP): Measured during VCTE, estimates steatosis in d/Bm. However, less accurate than MRI-PDFF and not required for fibrosis staging