Laboratory Tests for Iron Stores and Iron Availability

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


Tests of iron metabolism[✎ edit | edit source]

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[✎ edit | edit source]

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.