I r o n - D e f i c i e n c y A n e m i a
Iron Facts
Absorption
• Occurs in duodenum/proximal jejunum
• In mucosal cells, iron is bound to either ferritin (for storage) or transferrin
(for circulation).
Circulation
• Iron is bound to transferrin in Fe state.
• Transferrin carries iron to red blood cell precursors in bone marrow, and to
other organs.
Distribution
• Hemoglobin -- 70%
• Storage (ferritin and hemosiderin) -- 30%
• Transferrin-bound -- less than 0.1%
Metabolism
• Most of the circulating iron is taken up by red cell precursors and
incorporated into heme (which is then combined with globin chains to bake
hemoglobin)
• The rest of the iron is stored in macrophages in the marrow, spleen, and liver.
Storage of iron
• Ferritin: Labile iron storage form (quick in, quick out). Used for heme
synthesis.
• Hemosiderin: Stable storage form (but iron less available). Contains ferritin
and cell debris.
Causes of Iron Deficiency
Decreased iron intake
• Dietary deficiency (rarely the sole cause of iron deficiency anemia!)
• Decreased absorption (e.g., achlorhydria, gastric surgery)
Increased iron loss
• GI bleeding (e.g., from gastric ulcer, colon cancer)
• Excessive menstrual flow (menorrhagia) (most common cause of IDA in
females).
• Acute blood loss (e.g., massive trauma, childbirth)
• Increased iron requirement (e.g., pregnancy)
• It boils down to this:
1. IDA in premenopausal women: First things to consider are menorrhagia
and/or repeated pregnancies.
2. IDA in men and postmenopausal women: First thing to consider is GI
blood loss.
Clinical Features
Symptoms
• fatigue, palpitations, dizziness, breathlessness
• patients might have NO symptoms if:
• the anemia is mild or moderate (hemoglobin >8 or so)
• the anemia is chronic (long-standing, slowly-progressing).
Signs
• Skin, mucous membranes: pallor.
• Nails: thinning, flattening, koilonychia (spoon-shaped nails).
• Tongue: atrophy of lingual papillae leaves tongue smooth, shiny.
Pica
• Hippocrates: a "craving to eat the earth" associated with "corruption of the
blood."
• This is a disorder in which patients either eat non-food items
(like dirt), or eat excessive amounts of food items (like flour or ice).
Many cases occur in patients who are iron-deficient, for some mysterious
from Clinical Methods.
Morphology
Blood
• Hypochromic, microcytic anemia.
• Increased anisocytosis - often the first sign of impending IDA.
• Increased poikilocytosis (look for elliptocytes).
• Decreased reticulocyte number (not enough iron around to make them!).
• Platelet count usually increased (up to twice the normal count).
Bone marrow
• Dyserythropoiesis
• Decreased iron stores (need to do a special stain for iron to see this)
Iron studies
• Decreased serum iron
• Increased TIBC (total iron binding capacity)
• Decreased ferritin
Treatment
• Figure out why patient is iron deficient (don't just treat the anemia, or you
might miss something really important).
• Then give iron (orally).
