What is the diagnosis and treatment for a patient with mild anemia, slightly low red blood cell count, and elevated platelet count?

Laboratory Interpretation and Clinical Approach

This patient has borderline mild anemia with reactive thrombocytosis and relative lymphocytosis, most likely representing iron deficiency anemia (IDA) requiring iron studies and evaluation for gastrointestinal blood loss before any treatment is initiated.

Key Laboratory Findings

The complete blood count reveals several important patterns:

• Mild anemia: RBC count 4.17 (slightly below normal 4.20-5.80), hemoglobin 13.8 g/dL (within normal range but at lower end), hematocrit 41.1% (normal) 1
• Borderline macrocytosis: MCV 98.6 fL (high-normal, approaching upper limit of 100 fL) 2
• Reactive thrombocytosis: Platelet count 404 (elevated above 400) 3, 4
• Relative neutropenia with lymphocytosis: Neutrophils 37.1% (below normal 38-80%), absolute neutrophils 2115 (normal), lymphocytes 46.2% (upper normal) 5

Diagnostic Evaluation Required

Before initiating any treatment, a complete iron deficiency workup must be performed 6:

• Serum ferritin (most powerful test; <12 μg/dL diagnostic of iron deficiency, though may be falsely elevated with inflammation/malignancy) 6
• Transferrin saturation (<30% suggests iron deficiency) 6
• Complete iron panel including serum iron and total iron-binding capacity 1
• Reticulocyte count to assess bone marrow response 1, 2
• Peripheral blood smear examination for RBC morphology 7, 2

Gastrointestinal Evaluation

Since gastrointestinal blood loss is the most common cause of iron deficiency in adults (particularly with thrombocytosis as a reactive phenomenon), endoscopic evaluation is mandatory 6:

• Upper endoscopy with small bowel biopsy to exclude gastric cancer, peptic ulcer disease, NSAID-related injury, and celiac disease 6
• Colonoscopy or barium enema to exclude colonic cancer, polyps, angiodysplasia, and inflammatory bowel disease 6
• Assess for occult blood loss and evaluate renal function 1
• Check for NSAID use, previous gastrectomy, and dietary history 6

Understanding the Thrombocytosis

The elevated platelet count (404) is likely reactive thrombocytosis secondary to iron deficiency 3, 4:

• Thrombocytosis occurs in 13.3% of adults with IDA, typically mild (as in this case) 4
• Erythropoietin elevation correlates with both anemia and increased platelet counts, though the mechanism remains unclear 3
• Platelet count normalizes with iron replacement in most cases 3
• Thrombocytopenia can also occur (2.1% of IDA cases), so monitor during treatment 4

Treatment Approach

Treatment should only begin after identifying and addressing the underlying cause 1:

1. Oral iron supplementation is first-line once iron deficiency is confirmed 6
2. Monitor iron status closely during treatment to detect iron loading 6
3. Weekly complete blood counts initially, then as clinically indicated 1
4. Reassess at 3 months for treatment response 6

Important Caveats

• Do not assume the anemia is mild and insignificant: Even mild anemia may indicate serious underlying pathology such as gastrointestinal malignancy 6
• The normal hemoglobin does not exclude iron deficiency: Early iron deficiency may present with thrombocytosis before significant anemia develops 3, 4
• Borderline MCV requires careful interpretation: Combined deficiencies (iron plus folate/B12) may normalize MCV despite iron deficiency 6
• Relative lymphocytosis and neutropenia are non-specific: May be normal variant or reflect chronic inflammation; correlate with clinical context 5