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HelpTest Code FET Iron, Liver Tissue
Reporting Name
Iron, Liver TsUseful For
Diagnosis of hemochromatosis using liver tissue specimens
Testing Algorithm
For more information see Hereditary Hemochromatosis Algorithm.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Liver TissueNecessary Information
Patient's date of birth is required to calculate iron index.
Specimen Required
Supplies: Metal Free Specimen Vial (T173)
Container/Tube:
Preferred: Mayo metal-free specimen vial
Acceptable: Paraffin block, with no more than 1 or 2 cuts previously made
Specimen Volume: 2 mg
Collection Instructions: Two mg of liver tissue are required. This is typically a piece of tissue from a 22-gauge needle biopsy at least 2 cm long. If an 18-gauge needle is used, the tissue must be at least 1 cm in length.
Additional Information: Paraffin blocks will be returned 7 days after analysis is complete.
Specimen Minimum Volume
Needle biopsy: See Specimen Required; 2 mm x 2 mm (punch): 0.3 mg by dry weight
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Liver Tissue | Refrigerated (preferred) | ||
| Ambient | |||
| Frozen | |||
Special Instructions
Reference Values
Iron
Males: 200-2,400 mcg/g dry weight
Females: 200-1,800 mcg/g dry weight
Iron Index
≥13 years: <1.0 mcmol/g/year
Reference values have not been established for patients that are younger than 13 years.
Day(s) Performed
Monday, Thursday
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
83540
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| FET | Iron, Liver Ts | 57028-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 8350 | Iron, Liver Ts | 57028-3 |
| 7770 | Hepatic Iron Index | 49061-5 |
Interpretation
A hepatic iron concentration above 10,000 mcg/g dry weight is diagnostic for hemochromatosis.
Hepatic iron concentrations above 3000 mcg/g are seen when there is iron overload without cellular injury and cirrhosis. Hepatic iron concentrations greater than the reference range are associated with hemosiderosis, thalassemia, and sideroblastic anemia. Some patients with hepatitis or cirrhosis without significant fibrosis will have hepatic iron concentrations at the top end of normal or just slightly above the normal range.
Iron accumulates in the liver normally with aging. The hepatic iron index (HII) normalizes hepatic iron concentration for age. The HII is calculated from the hepatic iron concentration by converting the concentration from mcg/g to mcmol/g dry weight and dividing by years of age. The normal range for HII is less than 1.0.
-Patients with homozygous hemochromatosis have an HII above 1.9.
-Patients with heterozygous hemochromatosis often have an HII ranging from 1.0 to 1.9.
-Patients with hepatitis and alcoholic cirrhosis usually have an HII below 1.0, although a small percentage of patients with alcoholic cirrhosis have an HII in the range of 1.0 to 1.9.
-Patients with hemochromatosis who have been successfully treated with phlebotomy will have an HII below 1.0.
Liver specimens collected from patients with cirrhosis containing a high degree of fibrosis have results near the low end of the reference range, even though they will show significant iron staining in hepatocytes. While it is true that iron accumulates in hepatocytes in advanced alcoholic cirrhosis with fibrosis, there are relatively few hepatocytes compared to other inert (fibrotic) tissue, so the quantitative iron determination, which is expressed as microgram of iron per gram of dry weight tissues, yields a low result. Histologic examination of all tissue specimens should be performed to facilitate correct interpretation. When structural heterogeneity is apparent histologically, variation in measured iron should be anticipated. In approximately 2% of cases, a high degree of hepatic heterogeneity has been observed that makes quantitation highly variable.
Clinical Reference
1. Brandhagen DJ, Fairbanks VF, Baldus W. Recognition and management of hereditary hemochromatosis. Am Fam Physician. 2002;65:853-860, 865-866
2. Summers KM, Halliday JW, Powell LW. Identification of homozygous hemochromatosis subjects by measurement of hepatic iron index. Hepatology. 1990;12:20-25
3. Ludwig J, Batts KP, Moyer TP, et al. Liver biopsy diagnosis of homozygous hemochromatosis: a diagnostic algorithm. Mayo Clin Proc. 1993;68:263-267
4. Pietrangelo A. Hemochromatosis: an endocrine liver disease. Hepatology. 2007;46:1291-1301
5. Ashley EA, Butte AJ, Wheeler MT, et al. Clinical assessment incorporating a personal genome. Lancet. 2010;375:1525-1535
6. McLaren CE, Barton JC, Eckfeldt JH, et al. Heritability of serum iron measures in the hemochromatosis and iron overload screening (HEIRS) family study. Am J Hematol. 2010;85:101-105
7. Radford-Smith DE, Powell EE, Powell LW. Haemochromatosis: a clinical update for the practising physician. Intern Med J. 2018;48(5):509-516. doi:10.1111/imj.13784
Report Available
3 to 6 daysMethod Name
Inductively Coupled Plasma Mass Spectrometry (ICP-MS)