A 38-year-old woman is evaluated in the outpatient clinic for progressively worsening fatigue, decreased exercise tolerance, and a persistent craving to chew on ice. She mentions that her menstrual periods have been exceptionally heavy over the last six months, often requiring her to change pads every two hours. Her vital signs are stable and within normal limits.
Initial laboratory testing reveals the following results:
| Test | Result | Reference Range |
|---|---|---|
| Hemoglobin | 8.8 g/dL | 12.0 - 15.5 g/dL |
| Mean corpuscular volume (MCV) | 74 fL | 80 - 100 fL |
| Serum ferritin | 9 ng/mL | 15 - 200 ng/mL |
| Serum iron | 35 g/dL | 60 - 170 g/dL |
| Total iron-binding capacity (TIBC) | 480 g/dL | 240 - 450 g/dL |
Based on the provided laboratory panel, which of the following is the most accurate interpretation of this patient's hematologic status?
- Depleted iron stores secondary to chronic blood lossAnswer
- BIron sequestration secondary to a chronic inflammatory state
- CQuantitative defect in globin chain synthesis
- DDefective incorporation of iron into the heme molecule
- EImpaired red blood cell DNA synthesis
Answer
Depleted iron stores secondary to chronic blood loss
The correct answer accurately identifies the diagnosis as absolute iron deficiency. The patient's laboratory results show a microcytic anemia (MCV < 80 fL). The most critical test for distinguishing causes of microcytosis is serum ferritin, which reflects total body iron stores. A low ferritin level (typically < 15 ng/mL) is highly specific for iron deficiency. Furthermore, in absolute iron deficiency, the liver produces more transferrin in an attempt to maximize iron transport, leading to an elevated Total Iron-Binding Capacity (TIBC). The combination of low ferritin, low serum iron, and high TIBC perfectly aligns with depleted iron stores, which in this patient's case is secondary to chronic blood loss from heavy menstrual bleeding.
Step-by-Step Solution
Key Concept
Iron deficiency anemia is characterized by a microcytic anemia with low serum ferritin, low serum iron, and an elevated total iron-binding capacity (TIBC).