From the Guidelines
This CBC shows microcytic, hypochromic anemia with high RDW, consistent with iron deficiency anemia, and the most appropriate next step is to order iron studies, including serum ferritin, to confirm the diagnosis, as recommended by the British Society of Gastroenterology guidelines 1. The red blood cell count is slightly elevated at 5.31 x10E6/uL, while hemoglobin is at the lower limit of normal at 11.1 g/dL.
- The MCV (70 fL), MCH (20.9 pg), and MCHC (29.8 g/dL) are all decreased, indicating smaller red cells with less hemoglobin concentration.
- The elevated RDW (18.9%) suggests significant variation in red cell size, which is characteristic of iron deficiency. This pattern occurs because iron is essential for hemoglobin synthesis, and when iron stores are depleted, the body produces smaller red cells with less hemoglobin. Further workup should include investigation for sources of blood loss, particularly in the gastrointestinal tract, as iron deficiency may be caused by continuous blood loss from the ulcerated surface of the bowel, malnutrition with reduced iron intake, or impaired iron uptake through the duodeno-jejunal mucosa 1. Treatment typically involves oral iron supplementation, such as ferrous sulfate 325 mg daily or twice daily, taken with vitamin C to enhance absorption, and addressing any underlying cause of iron loss, as iron deficiency can lead to severe morbidity and even mortality if left untreated 1.
- A serum ferritin concentration of <15 μg/L is diagnostic of iron deficiency, and a cut-off of 45 μg/L provides a respectable specificity of 0.92, and figures below this may warrant consideration of GI investigation, especially in the context of a chronic inflammatory process with anaemia 1.
From the Research
CBC Interpretation
The provided CBC results indicate:
- Low RBC count: 5.31 x10E6/uL (normal range: 3.77-5.28 x10E6/uL) [flagged as high, but actually within normal range for some labs]
- Low Hemoglobin: 11.1 g/dL (normal range: 11.1-15.9 g/dL) [at lower limit of normal]
- Low Hematocrit: 37.2% (normal range: 34.0-46.6%) [within normal range]
- Low MCV: 70 fL (normal range: 79-97 fL) [indicative of microcytic anemia]
- Low MCH: 20.9 pg (normal range: 26.6-33.0 pg) [indicative of microcytic anemia]
- Low MCHC: 29.8 g/dL (normal range: 31.5-35.7 g/dL) [indicative of microcytic anemia]
- High RDW: 18.9% (normal range: 11.7-15.4%) [indicative of anisocytosis]
Possible Causes
Based on the studies provided, the low MCV, MCH, and MCHC values suggest microcytic anemia 2, 3, 4. The most common cause of microcytic anemia is iron deficiency anemia 2, 3. Other possible causes include anemia of chronic disease, thalassemia, and sideroblastic anemia 2.
Key Findings
- Microcytic anemia is characterized by small, often hypochromic, red blood cells 2
- Iron deficiency is the most common cause of microcytic anemia 2, 3
- Low serum ferritin is the best single laboratory parameter for the diagnosis of iron deficiency 3
- A detailed history and physical examination with appropriate laboratory test results can help detect the correct cause of anemia in most patients 4
Note: Study 5 is not relevant to the interpretation of the CBC results.