What blood tests are used to diagnose hemochromatosis in a patient with a potential iron overload condition?

Blood Work to Diagnose Hemochromatosis

The essential blood tests to diagnose hemochromatosis are transferrin saturation (TSAT) and serum ferritin, measured simultaneously as the first-line screening approach. 1

Initial Screening Panel

The iron panel should include:

• Transferrin saturation (TSAT): Calculated as serum iron divided by total iron binding capacity (TIBC) × 100 1, 2
• Serum ferritin 1
• Full blood count with reticulocytes: To exclude anemia and red cell disorders 1
• Serum iron and transferrin (or TIBC): Provides additional information for differential diagnosis 1

Never rely on a single test—both TSAT and ferritin together provide optimal diagnostic accuracy. 2

Diagnostic Thresholds

Biochemical evidence suggesting hemochromatosis includes:

• Transferrin saturation >45% in females or >50% in males 1
• Serum ferritin >200 μg/L in females 1
• Serum ferritin >300 μg/L in males and post-menopausal women 1

TSAT ≥45% is the primary screening threshold with high sensitivity for detecting hereditary hemochromatosis, though it has lower specificity and may identify secondary iron overload. 2

Genetic Testing Following Abnormal Iron Studies

If either TSAT or ferritin exceeds these thresholds, proceed immediately to HFE gene mutation analysis testing for C282Y and H63D mutations. 1, 2 This is the most cost-effective next step, as C282Y mutation is present in approximately 90% of hereditary hemochromatosis patients. 2

For patients of non-European origin, the pre-test likelihood of detecting C282Y is very low, so direct sequencing of HFE and non-HFE genes (including HJV, TFR2, CP, and SLC40A1) should be considered without initial HFE genotyping. 1

Additional Liver Assessment

Once iron overload is suspected, obtain:

• Liver transaminases (ALT, AST) 1, 2
• Platelet count 2

The combination of ferritin >1,000 μg/L, elevated ALT/AST, and platelet count <200 predicts cirrhosis in approximately 80% of C282Y homozygotes. 2 Conversely, ferritin <1,000 μg/L with normal transaminases and no liver enlargement indicates very low risk of advanced fibrosis. 1

Critical Pitfalls to Avoid

Ferritin is an acute phase reactant and can be falsely elevated in numerous conditions unrelated to iron overload, including: 1, 2

• Chronic alcohol consumption
• Inflammatory conditions
• Metabolic syndrome and fatty liver disease
• Malignancy
• Cell necrosis

These conditions must be excluded before attributing elevated ferritin solely to hemochromatosis. 1 A normal TSAT with isolated ferritin elevation is an unusual pattern for classic HFE-related hemochromatosis, which typically presents with elevated TSAT as the earliest marker. 2

Blood samples for TSAT should be drawn in the morning, though fasting does not improve diagnostic utility. 1 TSAT shows significant biological variability, so confirm elevated values with repeat testing. 1, 2

What NOT to Order

Measuring hepcidin is not recommended for diagnosing hemochromatosis. 1

Confirming the Diagnosis

In C282Y homozygotes, the diagnosis of hemochromatosis is confirmed by the combination of:

• Elevated TSAT (>45% females, >50% males) 1
• Elevated ferritin (>200 μg/L females, >300 μg/L males) 1
• Positive genetic testing 1

In patients with elevated TSAT and ferritin but other HFE genotypes (such as C282Y/H63D compound heterozygotes), diagnosis requires demonstration of hepatic iron overload on MRI or liver biopsy. 1