Laboratory Tests for Iron Stores and Iron Availability

Iron; needed for life, but potentially very toxic (free radicals)

Tests of iron metabolism
Serum iron ( SI)
 * F: 600-1400 mg/L, 11-25mmol/L
 * M: 750-1500 mg/L, 13-27mmol/L
 * Low in Fe deficiency and chronic disease
 * High in hemolytic syndromes and iron overload

Total iron binding capacity (TIBC)
 * amount of iron needed to bind to all the transferrin
 * 2500 – 4500 mg/L, 45-82 mmol/L
 * High in Fe deficiency
 * Low in chronic disease

Serum ferritin
 * Fe storage glycoprotein
 * Can store up to 2000 Fe
 * 30-300 ng/mL)
 * Serum level is very low, but closely correlates with level in cells
 * Closely correlates with total body Fe stores
 * <12 ng/mL Fe deficiency
 * Elevated in Fe overload, liver injury, tumors (Acute phase protein)
 * Tests for iron metabolism

Additional;

Serum transferin receptor Increase in increased erythropoiesis and early Fe deficiency

RBC ferritin

storage status over the previous 3 month (Fe deficiency/overload) unaffected by liver function or acute illness

Free RBC porphyrin

increased when heme synthesis altered

Iron Deficiency Anemia
Prelatent; (Decreasing iron stores of organism)
 * Decrease in serum ferritin – most sensitive parameter
 * decrease of iron in BM – (iron is in BM cells in form of ferritin)
 * increase TIBC (body has tendency to increase the absorption of iron and iron transporting capacity)this leads to decrease in Tf saturation even when serum iron is normal

Latent; (Decreases serum iron available for erythropoiesis)
 * decrease serum iron
 * further decrease Tf saturation
 * increase sTfR

Manifest anemia
 * parameters of anemia (low Hb, Hct, Erythrocyte count)
 * anemia of iron deficiency is hypochromic and microcytic

Anemia of chronic diseases	Anemia due to lack of iron	Myelodysplastic syndrome Serum iron

Transferrin/TIBC

ferritin

Iron is locked into macrophages to be out of reach of bacteria 	Lack of stores, see prelatent, latent and manifest anemia	Aplastic disorder of BM, enough iron in organism