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.