Liver Iron Concentration (LIC) Interpreter
Liver Iron Concentration (LIC) Interpreter
Grade hepatic iron loading from an MRI R2* or biopsy liver iron concentration, and see the chelation threshold each band implies.
Liver Iron Concentration (LIC)
LIC → overload gradeLIC 4.5 mg/g dry weight
Units and conversion
LIC (mg/g dw) ≈ 0.0254 × R2* (Hz) + 0.202
- mg/g dw
- the conventional unit, from biopsy or calibrated MRI
- R2*
- MRI relaxation rate; the calibration equation is sequence- and vendor-specific
- µmol/g dw
- mg/g dw × 17.9, using the atomic weight of iron
Worked example
LIC 4.5 mg/g dry weight
4.5 is between 3 and 7 mg/g dw → mild overload
= 80.6 µmol/g dry weight
Grading
| LIC mg/g dw | µmol/g dw | Grade | Action |
|---|---|---|---|
| < 1.8 | < 32 | Normal | None |
| 1.8 – 3 | 32 – 54 | Upper normal | Maintenance target on chelation |
| 3 – 7 | 54 – 125 | Mild | Start or continue chelation |
| 7 – 15 | 125 – 269 | Moderate | Intensify chelation |
| > 15 | > 269 | Severe | Intensive or combination chelation |
Measuring and interpreting liver iron
Liver iron concentration is the best available proxy for total body iron stores, because the liver holds the majority of storage iron and its concentration tracks the whole-body burden closely. It has replaced serum ferritin as the primary measure for managing transfusional overload, since ferritin is confounded by inflammation and responds slowly and unpredictably to chelation.
Measurement has moved almost entirely from biopsy to MRI. R2* and R2 relaxometry give a non-invasive concentration with good agreement against biopsy, without sampling error in a fibrotic liver and repeatable often enough to steer chelation dose. The calibration equation converting relaxation rate to mg/g dry weight is specific to the sequence and vendor, which is why scans should be done on the same platform when following a patient over time.
The critical caveat is that liver and heart load and unload on different timescales, through different mechanisms. A patient can have a well-controlled liver iron and a dangerously low cardiac T2*, and cardiac siderosis remains the leading cause of death in transfusion-dependent thalassaemia. Liver iron guides overall chelation intensity; it never substitutes for cardiac assessment.
Frequently asked questions
What is a normal liver iron concentration?
Below about 1.8 mg per gram dry weight, equivalent to under 32 µmol/g. In a transfused patient on chelation, 3 to 7 mg/g is a commonly accepted maintenance target.
How do I convert mg/g to µmol/g?
Multiply by 17.9, derived from the atomic weight of iron. A liver iron of 4.5 mg/g dry weight is 80.6 µmol/g dry weight.
Does a normal liver iron mean the heart is safe?
No. Liver and cardiac iron load and clear on different timescales, and cardiac siderosis can be severe with a well-controlled liver iron. Cardiac T2* must be measured separately.
Is ferritin good enough instead?
For screening and trend monitoring it has a role, but it is distorted by inflammation and correlates only loosely with body iron. Where chelation decisions depend on the number, MRI-based liver iron is the standard.
Related calculators
References
- Wood JC. Guidelines for quantifying iron overload. Hematology Am Soc Hematol Educ Program. 2014;2014(1):210–5.
- Thalassaemia International Federation. Guidelines for the Management of Transfusion Dependent Thalassaemia.