What biomarker is most consistent with iron deficiency anemia in a patient with heavy menstrual bleeding and low hemoglobin?

Total Iron-Binding Capacity (TIBC) is Most Consistent with Iron Deficiency Anemia in a Patient with Heavy Menstrual Bleeding

In a 35-year-old nonpregnant female with heavy menstrual bleeding and a hemoglobin of 10.4 g/dL, an elevated total iron-binding capacity (TIBC) would be most consistent with iron deficiency anemia. 1

Diagnostic Markers for Iron Deficiency Anemia

Ferritin

• Serum ferritin is the single most useful and specific marker for iron deficiency in the absence of inflammation 1
• A serum ferritin <15 μg/L is highly specific (specificity 0.99) for iron deficiency 1
• However, ferritin is an acute phase reactant and can be falsely normal or elevated in inflammatory conditions 1
• In a patient with heavy menstrual bleeding without inflammation, ferritin would be decreased, not elevated 1

Total Iron-Binding Capacity (TIBC)

• TIBC is increased in iron deficiency anemia 1
• Raised TIBC is one of the key markers suggestive of iron deficiency anemia 1
• In the context of chronic blood loss from heavy menstrual bleeding, elevated TIBC reflects the body's attempt to increase iron transport capacity in response to iron deficiency 1

Transferrin Saturation

• Transferrin saturation is calculated as (serum iron/TIBC) × 100 1
• In iron deficiency, transferrin saturation is typically low (<16-20%), not elevated 1
• A transferrin saturation <16% is suggestive of iron deficiency anemia 1

Hepcidin

• Hepcidin levels are typically decreased in iron deficiency anemia, not elevated 2
• Hepcidin is the main regulator of iron homeostasis and is suppressed when iron stores are low to increase iron absorption and mobilization 2

Reticulocyte Count

• Reticulocyte count is typically normal or low in untreated iron deficiency anemia 3
• It increases only after effective iron therapy is initiated 3, 4
• An elevated reticulocyte count would not be consistent with untreated iron deficiency anemia 3

Clinical Context in Heavy Menstrual Bleeding

• Heavy menstrual bleeding is a common cause of iron deficiency anemia in women of reproductive age 2, 4

• The chronic blood loss leads to iron depletion, which progresses through stages:

  1. Depleted iron stores (low ferritin)
  2. Iron-deficient erythropoiesis (low serum iron, elevated TIBC)
  3. Iron deficiency anemia (low hemoglobin) 1, 3

• In this patient with a hemoglobin of 10.4 g/dL (below the normal range of 12.0-15.0 g/dL for women), the anemia is likely due to iron deficiency from chronic menstrual blood loss 1, 2

Common Pitfalls in Diagnosis

• Relying solely on ferritin can be misleading if there is concurrent inflammation 1
• In the absence of inflammation, serum ferritin <30 μg/L is diagnostic of iron deficiency 1
• When inflammation is present, ferritin up to 100 μg/L may still be consistent with iron deficiency 1
• A good response to iron therapy (Hb rise ≥10 g/L within 2 weeks) is highly suggestive of iron deficiency, even with equivocal iron studies 1

In conclusion, among the listed biomarkers, an elevated total iron-binding capacity would be most consistent with iron deficiency anemia in this patient with heavy menstrual bleeding and low hemoglobin.