4.1: Iron Deficiency Anemia (IDA)

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: An image from a peripheral blood smear demonstrating hypochromic and microcytic red blood cells. 50x oil immersion. From MLS Collection, University of Alberta, https://doi.org/10.7939/R3P84499C

: An image from a peripheral blood smear showing hypochromic, microcytic red blood cells with occasional targets which can beeen in IDA. 60x oil immersion. From MLS Collection, University of Alberta, https://doi.org/10.7939/R3988333G

: An image from a peripheral blood smear showing hypochromic, microcytic red blood cells. 50x oil immersion. From MLS Collection, University of Alberta, https://doi.org/10.7939/R3KS6JK8F

Cause(s):^1,2

Chronic Blood Loss (heavy menstruation, intermittent GI bleeding, etc.)

Increased Need (periods of rapid growth, pregnancy)

Inadequate intake (diet)

Impaired absorption (malabsorption)

Notes: When there is not enough iron to meet the requirements of the body, iron stores begin to deplete, and IDA occurs. Development of IDA occurs over a period of time.^1-4

IDA development is said to occur in three stages:³

Stage 1

(Storage Iron Depletion):

– Normal RBC maturation

– Decline in storage iron (decreased ferritin, decreased iron stores in the bone marrow)

– No other evidence of anemia development.

Stage 2

(Transport Iron Depletion):

– Decreased serum iron and ferritin

– Transferrin and TIBC levels increase

– Absent iron stores in the bone marrow

– Evidence of anemia is not as apparent.

Stage 3

(Functional Iron Depletion- IDA):

– Anemia is evident

– PBS shows microcytic, hypochromic RBCs

– RBC development is affected

– Same iron study results as stage 2

– Hb is decreased

– Hepcidin is decreased

– Erythropoietin is increased

Laboratory Features of Iron Deficiency Anemia (At Stage 3):^1-4

CBC:

RBC Count: Decreased

PLT: Variable (increased in chronic bleeding)

Hb: Decreased

Hct: Decreased

MCV, MCH, MCHC: Decreased

RDW: Increased

PBS:

Microcytic, hypochromic RBCs

Target cells

Elliptocytes

Teardrop cells

Normal WBC morphology

BM:

M:E Ratio: Decreased

Erythroid hyperplasia

Iron Stores: Absent or severely decreased (not sustainable)

Iron Studies:

Serum Iron: Decreased

Ferritin: Decreased

Transferrin: Increased

Transferrin Saturation: Decreased

TIBC: Increased

Other Tests:

Prussian Blue stain of the BM shows absent or decreased iron

Reticulocyte count decreased

References:

1. McKenzie SB. Anemias of disordered iron metabolism and heme synthesis. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 198-230.

2. Miller JL. Iron deficiency anemia: A common and curable disease. Cold Spring Harb Perspect Med [Internet]. 2013 Jul 1 [cited 2018 Jun 28];3(7):10.1101/cshperspect.a011866 a011866. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3685880/

3. Doig K. Disorders of iron kinetics and heme metabolism. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 297-313.

4. Finnegan K. Iron metabolism and hypochromic anemias. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 117-37.