Microcytic Hypochromic Anemia - Iron Deficiency Anemia
This patient has iron deficiency anemia (IDA) and requires serum ferritin measurement for confirmation, followed by oral iron supplementation and investigation for the underlying cause of iron loss.
Diagnosis
The laboratory values reveal:
- Anemia: Hemoglobin 10.1 g/dL (below normal threshold of 12-13 g/dL) 1
- Microcytosis: MCV 79.4 fL (reduced, normal >80 fL)
- Hypochromia: MCH 23.3 pg and MCHC 29.3 g/dL (both reduced)
- Reactive thrombocytosis: Platelets 437,000/µL (elevated, commonly seen in IDA)
The combination of low hemoglobin with reduced MCV, MCH, and MCHC is pathognomonic for microcytic hypochromic anemia. MCH is actually a more reliable marker of iron deficiency than MCV alone, as it is less dependent on storage conditions and the counting machine used 1. The elevated platelet count is a typical reactive finding in iron deficiency.
Immediate Diagnostic Steps
Confirm iron deficiency with serum ferritin - this is the single most useful marker of IDA 1. Additional tests to order:
- Serum ferritin (most important)
- Transferrin saturation (helpful if false-normal ferritin suspected due to inflammation)
- Consider reticulocyte count to assess bone marrow response
Important Caveat
If iron studies are equivocal but clinical suspicion is high, a good response to iron therapy (Hb rise ≥10 g/L within 2 weeks) is highly suggestive of absolute iron deficiency 1. This can serve as both diagnostic and therapeutic.
Management Algorithm
1. Initiate Oral Iron Therapy
Start empiric oral iron supplementation while awaiting confirmatory tests, given the clear microcytic hypochromic picture.
2. Investigate the Source of Iron Loss
Investigation should be considered at any level of anemia in the presence of iron deficiency 1. The case is stronger with more severe degrees of anaemia, as serious underlying GI pathology is more likely.
Key investigations needed:
- Gastrointestinal evaluation: Upper and lower GI endoscopy (especially given this level of anemia warrants investigation for occult bleeding, malignancy)
- Menstrual history (if female and menstruating)
- Dietary assessment for inadequate intake
- Celiac serology (tissue transglutaminase antibodies)
- Stool for occult blood
3. Monitor Response
Recheck CBC in 2 weeks:
- Expected response: Hb rise ≥10 g/L confirms iron deficiency 1
- If no response, reconsider diagnosis or investigate for ongoing blood loss
Critical Pitfalls to Avoid
- Do not delay investigation: While this hemoglobin level (10.1 g/dL) may seem "mild," investigation should not be deferred, as colorectal cancer can present at any level of anemia with iron deficiency 1
- Beware of concurrent deficiencies: Co-existing vitamin B12 or folate deficiency can mask microcytosis, making MCV appear falsely normal 2. However, this patient's clear microcytosis makes this less likely
- Chronic disease can reduce sensitivity: Both MCV and MCH lose sensitivity for iron deficiency in the presence of chronic inflammatory conditions 1
White Blood Cell Parameters
The leukocyte differential (neutrophils 73%, lymphocytes 24%, eosinophils 3%) is within normal limits and does not suggest infection, inflammation, or hematologic malignancy requiring immediate attention. The total WBC of 8,800/µL is normal 3.