2025 – PAGE 288 – HEMATOLOGY & ONCOLOGY

LAB REVIEWS – FERRITIN, TIBC, RDW, & TRANSFERRIN SATURATION

• FERRITIN:
  • Extremely low (< 15) = Iron deficiency anemia.
  • HIGH = Anemia of chronic disease or INFLAMMATION
• TIBC:
  • High = Iron deficiency anemia
  • LOW = Anemia of chronic disease, lead poisoning, and just about anything else.
• RDW:
  • Anemia + LOW RDW may mean thaLOWssemia.
  • Anemia + HIGH RDW may mean early iron deficiency anemia.
• TRANSFERRINSATURATION:
  • LOW = Low iron
  • HIGH = Plenty of iron around to bind the empty sites

MACROCYTIC ANEMIA

MACROCYTIC ANEMIAS (AKA MEGALOBLASTIC ANEMIA)

Look for an MCV > 100 to indicate macrocytic anemias, AKA megaloblastic anemia. Keep in mind that an MCV up to 110 is NORMAL for a newborn.

(DOUBLE TAKE) FOLATE (B9) DEFICIENCY

Folate (Vitamin B9) deficiency results in a macrocytic anemia and glossitis (red, swollen tongue). In pregnant women, deficiency can lead to neural tube defects (such as spina bifida) in the unborn fetus.

PEARLS: Look for a diet poor in veggies or a history of goat milk ingestion.

PEARL: Both B12 and Folate deficiency can lead to hypersegmented neutrophils and neural tube defects. Deficiency of either can be masked by treatment with the other. Use the symptoms, diet history, and blood testing to get the diagnosis right the first time!

MNEMONIC: FOLATE deficiency form FOLIAGE (veggies) deficiency!

IMAGE: www.pbrlinks.com/FOLATE1 (hypersegmented neutrophils)

(DOUBLE TAKE) B12 DEFICIENCY (AKA CYANOCOBALAMIN DEFICIENCY)

Cyanocobalamin (Vitamin B12) deficiency can present as a macrocytic anemia in a patient with neurologic issues (paresthesias, ataxia, and decreased reflexes). This anemia may be called pernicious anemia. Maternal B12 deficiency can result in neural tube defects (e.g., spina bifida) in the unborn fetus. Common causes of B12 deficiency include diet (VEGANS) and an inability to absorb B12. Intrinsic factor is made by parietal cells in the stomach and is needed to absorb B12. If a child is born with INTRINSIC FACTOR DEFICIENCY, or if there are autoantibodies to intrinsic factor, or if gastric surgery results in a lack of parietal cells, then the child can develop B12 deficiency. B12 is absorbed in the terminal ileum, which means B12 deficiency can also result from bac­terial overgrowth, inflammatory bowel disease (IBD), or short bowel syndrome. Treat with IM B12 injections.

PEARLS: B12 will likely be seen on the exam. KNOW that B12 = cyanocobalamin. In a B12-deficient patient, if the macrocytic anemia mistakenly treated with folate supplements, the B12 deficiency will be MASKED as the megaloblastic anemia improves. This can eventually lead to irreversible neurologic damage.