What are the appropriate diagnostic tests for hemochromatosis?

Diagnostic Testing for Hemochromatosis

The initial diagnostic approach requires simultaneous measurement of transferrin saturation (TS) and serum ferritin, followed by HFE genetic testing if either TS ≥45% or ferritin exceeds sex-specific thresholds (>300 μg/L in men, >200 μg/L in women). 1

Initial Laboratory Evaluation

Both transferrin saturation and serum ferritin must be obtained together as the first-line tests—never rely on a single test. 1, 2 This combination provides optimal diagnostic accuracy for detecting hereditary hemochromatosis. 1, 3

Transferrin Saturation (TS)

• TS is the most sensitive early marker for hemochromatosis and should be calculated as serum iron/total iron-binding capacity × 100. 1, 2
• A threshold of ≥45% triggers further evaluation and has the highest sensitivity for detecting C282Y homozygotes. 1, 3
• TS ≥45% is the primary screening threshold that mandates proceeding to genetic testing. 1, 2

Serum Ferritin

• Sex-specific thresholds are >300 μg/L in men and >200 μg/L in women. 1, 2
• Ferritin has less biological variability than TS but can be falsely elevated by inflammation, liver disease, malignancy, and metabolic syndrome—making it less specific when used alone. 1, 3, 4
• A normal TS with elevated ferritin may still indicate iron overload in non-HFE hemochromatosis or C282Y/H63D compound heterozygotes, requiring further investigation. 1, 3

Genetic Testing Algorithm

When either TS ≥45% or ferritin exceeds the upper limit of normal, immediately proceed to HFE mutation analysis for C282Y and H63D variants. 1, 2

Interpretation of Genetic Results

• C282Y homozygosity (C282Y/C282Y) confirms HFE-related hereditary hemochromatosis and accounts for 85-90% of clinically affected patients. 1, 2, 5
• Compound heterozygotes (C282Y/H63D) may have mild iron overload, especially with additional risk factors, and require individualized assessment based on iron studies rather than genotype alone. 1, 2, 4
• In patients of non-European origin with elevated TS and ferritin, the pre-test likelihood for C282Y is very low; direct sequencing of HFE and non-HFE genes (HJV, TFR2, CP, SLC40A1) should be considered. 1

Assessment for Advanced Liver Disease

Liver biopsy is indicated when any of the following are present: 1, 2

• Ferritin >1,000 μg/L
• Elevated liver enzymes (ALT or AST)
• Hepatomegaly on examination
• Age >40 years in C282Y homozygotes
• Platelet count <200 × 10⁹/L

A ferritin <1,000 μg/L accurately predicts the absence of cirrhosis, independent of the underlying disease.** 1, 3, 4 Conversely, **ferritin >1,000 μg/L combined with elevated aminotransferases and platelet count <200 predicts cirrhosis in 80% of C282Y homozygotes. 1, 3

Clinical Presentations Warranting Testing

Iron studies should be obtained in patients presenting with: 2

• Fatigue, right-upper-quadrant discomfort, or metacarpophalangeal joint arthralgia
• Sexual dysfunction, heart failure symptoms, or diabetes mellitus
• Physical findings including hepatomegaly, skin hyperpigmentation, testicular atrophy, congestive heart failure, arthritis, or chondrocalcinosis
• Unexplained abnormal liver enzyme results
• First-degree relatives of confirmed hemochromatosis patients

Family Screening

Once a proband is identified, all first-degree relatives should undergo simultaneous HFE genetic testing and phenotypic screening (TS and ferritin) at a single visit. 1, 2 For children of a proband, testing the other parent is recommended—if that parent is normal, the child is an obligate heterozygote and requires no further testing. 1

Additional Diagnostic Considerations

Cardiac and Extrahepatic Evaluation

• Patients with severe iron overload (ferritin >1,000 μg/L) should be evaluated for arrhythmia and cardiac dysfunction with ECG and echocardiography. 1
• Cardiac MRI for myocardial iron quantification is indicated in patients with juvenile hemochromatosis or those with signs of heart disease. 1
• MRI can quantify hepatic iron concentrations non-invasively when the diagnosis is unclear or to assess extrahepatic organ involvement. 1, 2

Non-Invasive Fibrosis Assessment

• Non-invasive scores such as APRI and FIB-4 have been evaluated for detecting advanced fibrosis in hemochromatosis, but reported thresholds are lower than in other chronic liver diseases. 1
• Transient elastography shows high negative predictive value for advanced liver fibrosis, though larger validation studies are needed. 1

Critical Pitfalls and Caveats

Common causes of hyperferritinemia must be excluded before attributing elevated ferritin to hemochromatosis: 1, 4

• Chronic alcohol consumption
• Inflammatory conditions
• Cell necrosis and malignancy
• Non-alcoholic fatty liver disease and metabolic syndrome

Over 90% of hyperferritinemia cases are caused by these secondary factors rather than hereditary hemochromatosis. 4

A cutoff of 45% for TS has high sensitivity but lower specificity, potentially identifying secondary iron overload and heterozygotes who require further evaluation. 3 Approximately 11% of heterozygotes may have elevated ferritin and 8.6% may have elevated TS, but most do not have significant iron overload. 6

Hepcidin measurement is not recommended for diagnosing hemochromatosis. 1

Pre-Test Counseling

Before ordering genetic testing, discuss with the patient: 2

• The effectiveness of phlebotomy treatment
• Costs of testing and ongoing monitoring
• Implications for insurability and employment
• Psychological impact of disease labeling
• Family screening implications
• Possibility of uncertain or variant genotypes

Population Screening

Routine population-wide screening is not recommended due to low penetrance and uncertain benefit in asymptomatic genotype-positive individuals. 2 Targeted case-finding is appropriate for high-risk individuals with suggestive symptoms, abnormal liver function tests, family history, or one-time screening of asymptomatic non-Hispanic white men. 2