Can pernicious anemia present with high transferrin saturation (>55%) and elevated serum iron (>200 µg/dL), thereby mimicking hereditary hemochromatosis?

Can Pernicious Anemia Mimic Hemochromatosis with High TSAT and Serum Iron?

Yes, pernicious anemia can present with elevated transferrin saturation (>55%) and high serum iron (>200 µg/dL), creating a diagnostic mimicry of hereditary hemochromatosis, though this is a rare and paradoxical association.

The Paradoxical Association

While counterintuitive, the coexistence of pernicious anemia and iron overload parameters has been documented in case reports. One patient with confirmed pernicious anemia demonstrated a transferrin saturation of 95% and serum ferritin of 1,160 µg/L, ultimately found to be homozygous for the C282Y mutation of hereditary hemochromatosis 1. This represents a true dual diagnosis rather than pure mimicry, but highlights how pernicious anemia can coexist with—and potentially mask—iron overload conditions.

Understanding the Mechanism

The association appears paradoxical because:

• Pernicious anemia typically causes iron deficiency due to impaired absorption from atrophic gastritis
• However, ineffective erythropoiesis in pernicious anemia can lead to increased iron absorption through suppression of hepcidin
• The atrophic gastritis may actually provide a protective effect against full manifestation of hemochromatosis by limiting iron absorption 2

Critical Diagnostic Algorithm

When encountering elevated TSAT (>55%) and serum iron (>200 µg/dL):

Step 1: Assess the complete iron panel

• Measure serum ferritin alongside TSAT and iron
• In true hemochromatosis, ferritin is typically elevated (>200 µg/L in women, >300 µg/L in men) 3
• In pernicious anemia alone, ferritin may be normal or low despite high TSAT

Step 2: Evaluate for pernicious anemia markers

• Check complete blood count for macrocytic anemia (MCV elevated)
• Measure vitamin B12 levels
• Test for anti-intrinsic factor antibodies and anti-parietal cell antibodies
• Assess methylmalonic acid and homocysteine if B12 borderline

Step 3: Genetic testing for hemochromatosis

• Test for HFE mutations (C282Y and H63D) if TSAT persistently ≥50% in males or ≥40% in females with elevated ferritin 4
• This distinguishes true hereditary hemochromatosis from secondary causes

Step 4: Consider the clinical context

• Pernicious anemia presents with neurologic symptoms (paresthesias, ataxia, cognitive changes)
• Hemochromatosis presents with fatigue, arthralgia, skin pigmentation, hepatomegaly
• The presence of both conditions creates a mixed clinical picture

Key Clinical Pitfalls

Do not assume elevated TSAT always indicates iron overload. TSAT can be elevated in conditions with:

• Low transferrin levels (which increases the saturation percentage mathematically)
• Ineffective erythropoiesis (including megaloblastic anemia from B12 deficiency)
• Hemolysis or other causes of increased iron turnover

Do not rely on TSAT alone for diagnosis. The guidelines emphasize that both serum ferritin and transferrin saturation should be performed for case-finding 3. TSAT >55% suggests increased risk but requires further investigation with ferritin levels and potentially genetic testing 3.

Recognize that hemochromatosis patients have lower transferrin levels than normal individuals 5, which mathematically increases TSAT even with modest elevations in serum iron. This creates a situation where TSAT can appear dramatically elevated.

Management Implications

When both conditions coexist:

• Treat the pernicious anemia first with B12 replacement (intramuscular or high-dose oral)
• Reassess iron parameters after 2-3 months of B12 therapy, as correction of ineffective erythropoiesis may normalize some iron indices
• If genetic hemochromatosis is confirmed (C282Y homozygosity), the iron overload was only moderately increased in reported cases and responded rapidly to phlebotomy 1
• The pernicious anemia does not modify the cytologic presentation or treatment approach for either condition 1

The Bottom Line

Elevated TSAT and serum iron are not specific for hemochromatosis. The diagnostic approach must include assessment for other causes of altered iron metabolism, including pernicious anemia with its ineffective erythropoiesis. Always obtain a complete iron panel (iron, TSAT, ferritin, and transferrin), assess for macrocytic anemia and B12 deficiency, and proceed to genetic testing only when the clinical picture and persistent laboratory abnormalities support hereditary hemochromatosis 3, 6. The coexistence of both conditions, while rare, has been documented and requires treatment of both disorders.