Iron Deficiency Anemia and Disorders of Iron Excess

What is the majority of iron used for?

hemoglobin synthesis

1 mL of RBCs contains how much iron?

1 mg of iron

Where is iron stored and what is it stored as?

in macrophages or normoblasts as ferritin or hemosiderin

Iron Deficiency Anemia

- most common from in US
- early diagnosis is vital in infants (delay in cognitive/motor skills)
- oringially called chlorosis

Dietary absorption amounts to

1 mg/day
(men: 15 mg/day 6% intestinal absorption, women: 11 mg/day 12% intestinal absorption)

Dietary absorption is _______ in an iron deficient state

increased (max 20%)

What is the process of iron absorption?

Ferric > Ferrous > Ferric + transferrin

Transferrin receptors on nRBCs do what?

have the capacity to extract iron from plasma transferrin

Iron metabolism disorders may result from:

1. iron deficiency
2. block of the enzyme that inserts Fe into heme-ring

Common causes of IDA

- inc need (rapid growth, pregnancy)
- chronic loss of blood (GI bleed)
- lack of dietary intake
- faulty iron absorption in small intestine

Clinical Symptoms of IDA

- general anemia symptoms
- numb/tingly extremities
- atrophy of tongue skin w/ soreness
- cracks/ulcers in mouth
- PICA
- spoon shaped nails

What lab values are increased in IDA?

RDW (plt inc if anemia is due to blood loss), TIBC,

What are the iron reference ranges?

Serum iron (50-150), Saturated iron (20-55%), Serum ferritin (15-200), TIBC (250-400)

What is the most sensitive indicator of IDA?

serum ferritin (decreased bc stored iron is being pulled)

What is the formula for saturated iron?

(serum Fe/TIBC) X 100

What can be used to differentiate IDA and anemia of chronic disease?

Soluble Transferrin Receptor (sTfR) ELISA test

What does the bone marrow look like in IDA patients?

- small NRBCs w/ frayed margins
- stored Fe absent
- dec sideroblasts < 20% (normal 20-60%)

What is the first stage of IDA development?

Iron Depletion (negative iron balance and iron is moved from storage) dec plasma ferritin

Stage 2 of IDA development

Iron Deficiency Erythropoiesis (low levels of everything)

Stage 3 of IDA development

iron deficiency anemia

What can cause disorders of iron excess?

- inc intestinal absorption
- repeated transfusions
- iron complex drugs or vitamins

Hemochromatosis is associated with?

- joint pain
-fatigue
- abdominal pain
- liver/cardiac failure
- DM (diabetes mellitus)

What could be a fatal dose of iron for a young child?

50 mg

Primary Familial Hemochromatosis

- HFE gene (hepcidin)
- mutation leads to inc iron absorption
- TIBC dec
- everything inc

Sideroblastic Anemia

- defective use of iron during heme synthesis
- enzyme defects
- iron overload of mitochondria in normoblast
- myelodysplatic syndrome

What labs would you see with sideroblastic anemia?

- microcytic/hypochromic
- inc serum fe and transferrin
- marrow: big inc in Fe storage

What is the treatment for Hereditary Sideroblastic anemia (X-linked)?

vitamin B-6

What can cause acquired sideroblastic anemia?

- idiopathic or refractory
- secondary (malignancy or drugs)

What drugs can cause secondary sideroblastic anemia?

anti-tuberculosis (isoniazid), lead, chloramphenicol, ethanol