Diagnosis: Early Iron Deficiency Anemia with Evolving Hypochromia
This presentation of low hematocrit, low MCV, low MCHC, and low RBC count with normal hemoglobin and normal platelets represents early-stage iron deficiency anemia that requires immediate iron studies and treatment initiation. 1, 2
Understanding This Laboratory Pattern
The combination of low MCHC with elevated RDW is highly suggestive of iron deficiency, even when hemoglobin appears "normal," because the bone marrow produces red blood cells with progressively less hemoglobin content (low MCHC), while both normal-sized older cells and smaller, hypochromic newer cells coexist in circulation, creating high RDW. 1 This pattern indicates iron-deficient erythropoiesis that will progress to overt anemia if untreated. 1
MCH is actually a more reliable marker of iron deficiency than MCHC because it is less dependent on storage conditions and counting machine variations, and reduction occurs in both absolute and functional iron deficiency. 1
Immediate Diagnostic Workup Required
Essential Iron Studies
- Obtain serum ferritin and transferrin saturation immediately to confirm iron deficiency. 1, 2 Ferritin <30 μg/L confirms iron deficiency in the absence of inflammation. 1, 2
- Measure transferrin saturation, with <15-16% supporting iron deficiency and being less affected by inflammation than ferritin. 1
- Order reticulocyte count to evaluate bone marrow response to the anemia. 1, 2
- Measure C-reactive protein (CRP) to assess for inflammation, as ferritin can be falsely elevated in inflammatory states, chronic disease, malignancy, or liver disease. 1, 2
Critical Interpretation Points
In inflammatory conditions, ferritin up to 100 μg/L may still indicate iron deficiency, so clinical context is essential. 1, 3 If ferritin is 30-100 μg/L with elevated CRP, iron deficiency remains possible. 2
Investigation for Underlying Cause
All adult men and postmenopausal women with confirmed iron deficiency require endoscopic evaluation to exclude gastrointestinal malignancy, regardless of anemia severity. 1 For premenopausal women, assess menstrual blood loss patterns first. 1
Specifically evaluate for:
- Gastrointestinal bleeding sources (most common in adults without obvious blood loss) 1
- Dietary insufficiency (less common in developed countries)
- Malabsorption conditions (celiac disease, inflammatory bowel disease)
- Chronic blood donation or phlebotomy
Treatment Approach
If Iron Deficiency Confirmed (Ferritin <30 μg/L or TSAT <15-16%)
Initiate oral iron supplementation immediately while investigating the underlying cause. 1 A 1-3 month trial of oral iron is appropriate for most patients. 1
Reserve parenteral iron for patients who cannot tolerate or absorb oral preparations, or when rapid repletion is needed. 1
Monitor iron status during treatment to assess response and detect potential iron overload. 1
If Iron Studies Are Normal
- Consider hemoglobinopathies such as thalassemia trait and obtain hemoglobin electrophoresis, particularly in patients of Mediterranean, African, Middle Eastern, or Southeast Asian descent. 1
- Evaluate for anemia of chronic disease by assessing for underlying inflammatory conditions. 1, 2
Common Pitfalls to Avoid
Do not rely solely on hemoglobin levels to exclude significant anemia—this patient's "normal" hemoglobin masks evolving iron deficiency evident in the other indices. 1, 2
Do not misinterpret ferritin without considering inflammatory status, as inflammation falsely elevates ferritin levels and may mask true iron deficiency. 1, 2
Do not delay investigation of the underlying cause in adult men and postmenopausal women, as gastrointestinal malignancy must be excluded. 1
Do not assume dietary insufficiency alone without ruling out blood loss, as this is the most common cause in adults. 1