Anisocytosis with hypochromia and microcytes (IDA)
Iron-deficiency
anemia (IDA) is the most commonly encountered anemia and may be due to
[1] impaired iron intake, [2] pregnancy, [3] intravascular hemolysis,
[4] hemorrhage, or [5] lactation. IDA most often affects women in their
reproductive years and growing children. Each mL of packed RBC’s contain
about 1.0 mg of iron. The average adult contains about 3.5 to 5.0 grams
of iron. They will ingest about 15 to 20 mg of iron daily, excreting
most of it. The body normally absorbs about 1 mg of iron (which is equal
to the daily loss).
The iron taken into the body is in the ferric
state (Fe+3) in the stomach, it is changed to the ferrous state (Fe+2).
Ferrous iron is absorbed by the small intestine and in the intestinal
capillary system, iron is bound to transferrin to form a protein-iron
complex. This complex is carried to the bone marrow (and other cells
requiring iron) and will bind to the cell. The complex is absorbed into
the cell, the iron released, and the transferrin moves back into the
blood stream. Inside the cell, the iron is bound to the protein
apoferritin to form ferritin. The ferritin combines to form aggregates
which forms brown pigment granules called hemosiderin. IDA is a
hypoproliferative, microcytic, hypochromic anemia due to ineffective RBC
and/or hemoglobin production.
If IDA is observed in a healthy
appearing adult male, the physician should look for a gastrointestinal
lesion that may be losing blood. The menstruating woman will lose
between 50 and 70 mLs of blood monthly and when the iron is not being
replace anemia will result. It is estimated that up to 20% of the women
in the US have IDA. IDA produces a hypochromic, microcytic anemia. On
the peripheral blood smear, the erythrocytes are hypochromic and
microcytic. If IDA is severe, poikilo-cytosis and anisocytosis may be
obvious. In the bone marrow, the rubriblasts will be poorly
hemoglobinized and demonstrate ragged appearing cytoplasm. The serum
iron will be decreases and the total iron binding capacity (TIBC) will
be increased. The ferritin level will be less than 20 ng/mL.
IRON TRIVIAIf
dietary iron is from meat sources, it is heme bound. Vitamin C is not
required for absorption. If this iron is from eggs and vegetables, it is
in the ferritin and hemochrome bound form and requires vitamin C for
optimum absorption. In the stomach, the gastric fluid and pepsin
releases iron which passes into the gastrointestinal tract. Most iron
absorption occurs in the duodenum. Some iron absorption will occur in
the jejunum and ileum.
In developed countries, adequate ion intake is
not a problem. The high risk groups who are most likely to develop IDA
are [1] infants, [2] rapidly growing adolescents, [3] pregnant women,
and [4] women during their child bearing years (losing from 10 to 45
mg/month). The pregnant female need about 3.4 mg of iron daily (a total
of 1000 mg to carry the fetus to term). About 400 mg are needed for the
fetal RBC mass. At parturition, approximately 300 mg will be lost and up
to 170 mg will be contained in the placenta and umbilical cord.
It
has been estimated that a healthy adult male would require about eight
years to develop IDA if no more iron were absorbed in his diet.
Malabsorption is uncommon unless there is a primary problem as [1]
sprue, [2] gastrectomy, or [3] atrophic gastritis. Other causes are [1]
regular blood donations and [2] paroxysmal nocturnal hemoglobinuria.
CLINICAL SYMPTOMSEarly
stages (stage 1) are generally asymptomatic. As IDA develops into stage
two, the depletion of the body’s iron stores occurs, with the patient
experiencing hypoxia, characterized by lethargy and asthenia. As stage
two progresses, iron deficiency is demonstrated by a decrease in
erythropoiesis as iron is no longer being inserted into the hemoglobin
molecule. Lab testing will show decreases in serum iron, increased total
iron binding capacity (TIBC), and low transferrin saturation.
As the
IDA progresses into the stage three level, the mitotic activity of the
RBC increases resulting in small erythrocytes (microcytes) and
hypochromia. When the hypochromic microcyte is observed in the blood
film, there is also anisocytosis and poikilocytosis and IDA if fully
expressed. Symptoms that begin to appear in stage two and are fully
expressed in stage three are [1] ankle edema, [2] exertional dyspnea,
[3] headaches, [4] glossitis, [5] koilonychia, [6] pallor, [7] pica, and
[8] tachycardia. In the woman of child bearing age, [1] menorrhagia,
[2] irregular cycles, and/or [3] amenorrhea may occur.
CLINICAL LABORATORY FINDINGSRBC
count: Usually normal at the beginning. The count will usually remain
within normal limits unless the iron stores are severely
depleted.Hemoglobin: Will undergo greater degrees of reduction.
Individual are to be considered anemic if hemoglobin values fall as indicated in g/dL:
- [1] Children (from 6 months to 5 years) less than 11
- 2] Children (from 6 years to 14 years) less than 12
- Adult men. . . . . . . . . . . . . . . . . . . . . . less than 13
- Adult women. . . . . . . . . . . . . . . . . . . less than 12
- Pregnant women . . . . . . . . . . . . . . . . less than 11
RBC Indices: Anemia is suspected when the values fall as indicated:
- [1] MCV . . . . . 75 to 80 fL
- [2] MCH . . . . . 25 to 27 pG
- MCHC. . . . less than 32 percent
- [4] If the MCV is less than 75 fl.
- If the MCH is less than 25 pG
Retic Count: This test parameter may be normal or decreased in early IDA. As the IDA progresses, the retic count decreases
Fragility:
This test will usually be normal. If codocytes (target cells) are
present, then one may see a decreased value. The value of this test is
in detecting hereditary spherocytosis
WBC: The count is usually normal as is the differential
Platelet count: This testing parameter is usually normal
Serum Iron: decreases in stages as IDA develops
Normal values (μg/dL) as follows
- Newborn . . . . . . . 100 to 250
- Infant . . . . . . . . . 40 to 100
- Child . . . . . . . . . 50 to 120
- Adult male. . . . . . 65 to 170
- Adult female . . . . 50 to 170
Serum Ferritin:
Is an indicator of how much iron is being stored and it will
progressively decrease as IDA develops. It is the major iron storage
compound and is found in all body cells. It is a protein that is
complexed with iron. If iron is absent from this protein, it is then
know as apoferritin. This is an important test in differentiating IDA
from other types of microcytic normocytic anemias as it will be
increased in thalassemia and sideroblastic type anemias. Normal values
for men are 15 to 200 μg/L and women are 12 to 150 μg/L
Generalized test findings as IDA develops:
[1] In the initial stages when patient is asymptomatic:
- A. Serum ferritin will be decreased
- B. Bone marrow iron will be decreased
[2] In the second stage, when erythropoiesis is occurring withoutiron to insert in the heme portion of the hemoglobin molecule:
- A. Serum Ferritin continues to be decreased
- B. Bone marrow iron continues to be decreased
- C. Serum iron is now decreased
- D. TIBC is increased
[3] In the final stage with fully developed IDA
- A. Serum Ferritin, bone marrow iron, and serum iron are decreased
- B. TIBC is increased
- C. Hemoglobin and hematocrit are decreased
- D. MCV is decreased
- E. RDW is increased
