From the Guidelines
The patient's presentation of microcytic anemia with a ferritin level of 43 ng/mL and transferrin of 168 mg/dL suggests iron deficiency anemia, and I recommend starting oral iron supplementation with ferrous sulfate 325 mg (containing 65 mg elemental iron) taken once or twice daily on an empty stomach with vitamin C to enhance absorption. According to the study by 1, microcytic anemia is most commonly caused by iron deficiency, and the patient's ferritin level, although at the lower end of the normal range, may still indicate iron deficiency in the context of inflammation. The transferrin level of 168 mg/dL also suggests that the body is attempting to increase iron transport, which is consistent with iron deficiency anemia.
The diagnosis of iron deficiency anemia is supported by the laboratory values, and treatment should be initiated to replenish iron stores and improve the patient's quality of life. The study by 1 notes that absolute iron deficiency is characterized by iron and total iron binding capacity (TIBC) resulting in transferrin saturation less than 15% and ferritin less than 30 ng/mL, but the patient's ferritin level of 43 ng/mL may still indicate iron deficiency in the context of inflammation.
Treatment with oral iron supplementation should continue for 3-6 months, even after hemoglobin normalizes, to replenish iron stores. Side effects of iron supplementation, such as constipation, nausea, and black stools, can be managed by taking iron with food if needed, although this may reduce absorption. The patient should also undergo evaluation for the cause of iron deficiency, which commonly includes blood loss, malabsorption, or dietary insufficiency.
Follow-up testing should include complete blood count and iron studies after 4-8 weeks of therapy to monitor response to treatment. Key points to consider in the patient's management include:
- Monitoring for side effects of iron supplementation
- Evaluating for underlying causes of iron deficiency
- Assessing response to treatment with follow-up laboratory tests
- Continuing treatment for 3-6 months to replenish iron stores.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Microcytic Anemia Diagnosis
- Microcytic anemia is defined as the presence of small, often hypochromic, red blood cells in a peripheral blood smear and is usually characterized by a low MCV (less than 83 micron 3) 2.
- The most common cause of microcytic anemia is iron deficiency anemia, which can be diagnosed with low serum ferritin levels 3, 4.
- Serum ferritin measurement is the first laboratory test recommended in the evaluation of microcytosis, with low ferritin levels suggesting iron deficiency 3.
Iron Deficiency Anemia
- Iron deficiency anemia is the most common type of microcytic anemia and is also the most common anemia 4.
- Low serum ferritin is the best single laboratory parameter for the diagnosis of iron deficiency 4.
- The absence of bone marrow iron stores or the response to iron supplementation can be used to establish the diagnosis of iron deficiency 5.
Laboratory Tests
- Serum ferritin concentration is more suitable for assessment of iron deficiency than the serum iron concentration, the total iron-binding capacity or the percentual saturation of transferrin 5.
- The red cell distribution width (RDW) is the parameter with the highest sensitivity for iron deficiency (94%) 5.
- Transferrin saturation level, serum iron level, and possibly hemoglobin electrophoresis can be used to further evaluate microcytosis if the serum ferritin level is not initially low 3.
Given Values
- With a ferritin level of 43 and a transferrin level of 168, it is possible that the patient has iron deficiency anemia, but further evaluation is needed to confirm the diagnosis 2, 3, 4, 5.
- The patient's microcytic anemia could be due to other causes such as thalassemia, anemia of chronic disease, or sideroblastic anemia, and further testing such as hemoglobin electrophoresis may be necessary to determine the underlying cause 3, 6.