- Demonstrate how to estimate the red blood cell MCV.
A normal red blood cell is 2/3 the size of a small lymphocyte, or about the size of (or slightly smaller than)the lymphocyte nucleus. This man's peripheral blood smear shows red blood cells with hypochromasia and microcytosis
- What is the diagnosis from these findings?
Hypochromic microcytic anemia (from probable iron deficiency).
- Which of the following tests would be most useful to determine the
etiology of this patient's findings?
- A. Hemoglobin electrophoresis
- B. Reticulocyte count
- C. Stool for occult blood
- D. Vitamin B12 assay
- E. Bone marrow biopsy
Answer: C This patient most likely has a blood loss anemia,
and a colon cancer is a likely source in an older man. Laboratory testing
consistent with iron deficiency anemia would include a low serum ferritin
and low serum iron with low % saturation.
- What therapy would you offer this man?
If the anemia from iron deficiency is severe and symptomatic, then transfusion therapy is indicated as immediate intervention to treat the anemia, not the underlying iron deficiency. For most persons with iron deficiency, the anemia is mild to moderate and can be treated with oral iron therapy. Up to 300 mg per day of ferrous sulfate (20% elemental iron, or 60 mg) for an adult for a period of 6 to 12 months is a standard dose. Oral iron should be taken on an empty stomach, since foods may inhibit iron absorption. Up to 20% of patients may develop abdominal pain, nausea, vomiting, or constipation. Ferrous iron is mainly absorbed in the duodenum and jejunum where the mucosal cells oxidize it to ferric iron that is bound to ferritin. The iron stored in ferritin is slowly released and bound to plasma transferrin for transport to tissues.
Parenteral iron administration may be considered in patients who are unable to tolerate oral iron, who need acute therapy, or who have ongoing iron requirements from persistent blood loss, usually gastrointestinal loss. Intravenous iron dextran has a potential serious complication--anaphylaxis--and must be monitored closely.
Excessive iron can be toxic. Iron that is not bound to plasma transferrin can catalyze the formation of free radicals that can cause mitochondrial injury, lipid peroxidation, increased capillary permeability, vasodilation, and intestinal, renal, hepatic, myocardial, and pulmonary toxicity. Ingestion of 60 mg of elemental iron per kg of body weight can cause systemic toxicity. Generally, this is a greater problem for small children. The first signs of iron toxicity include vomiting and bloody diarrhea. Systemic effects include lethargy, hypotension, and metabolic acidosis. Severe iron poisoning can produce seizures, coma, pulmonary edema, vascular collapse, and liver injury with icterus, elevated liver enzymes, increased prothrombin time, and hyperammonemia.
- Define populations at risk for this condition.
Women in reproductive years and children are at greatest risk. Persons whose diet is poor or poorly balanced are at risk.
