What follow-up is needed for a 39-year-old female with stable laboratory results, including a Red Blood Cell (RBC) count of 5.37, Mean Corpuscular Volume (MCV) of 77.5, Mean Corpuscular Hemoglobin (MCH) of 25.0, and a platelet count of 464, over at least 4 years?

Evaluation of Stable Microcytic Anemia with Thrombocytosis

This patient requires iron studies (serum ferritin and transferrin saturation) to confirm iron deficiency anemia, and if confirmed, should be treated with oral iron supplementation. The stable 4-year pattern of microcytic anemia (MCV 77.5) with elevated RBC count (5.37) and reactive thrombocytosis (464) is highly consistent with chronic iron deficiency, likely from menstrual blood loss in a reproductive-age woman. 1

Diagnostic Workup Required

Iron deficiency confirmation is mandatory before assuming this is benign:

• Serum ferritin is the single most powerful test, with ferritin <30 μg/L confirming iron deficiency in the absence of inflammation, and <15 μg/L being diagnostic 1
• Transferrin saturation (TSAT) <15-20% supports iron deficiency and is less affected by inflammation than ferritin 1
• Reticulocyte count should be obtained to evaluate bone marrow response; a low or normal count indicates impaired red cell production 1

Critical Red Flag Assessment

The elevated platelet count (464 × 10³/μL) warrants specific attention:

• Reactive thrombocytosis commonly accompanies iron deficiency anemia and typically resolves with iron repletion 2
• However, platelet count >400 × 10³/μL has a positive likelihood ratio of 3.75 for giant cell arteritis in appropriate clinical contexts (though unlikely in a 39-year-old) 2
• More importantly, persistent thrombocytosis after iron correction would require hematology evaluation for primary myeloproliferative disorders 2

The Microcytic Polycythemia Pattern

The combination of elevated RBC count with low MCV creates a "microcytic polycythemia" pattern:

• Among patients with MCV <70 and elevated RBC counts, 74% had thalassemia minor, 11% had polycythemia vera, and 14% had secondary polycythemia with iron deficiency 3
• This patient's MCV of 77.5 makes thalassemia trait less likely (typically MCV <75), but it should still be considered if iron studies are normal 3
• If iron deficiency is confirmed and treated, the RBC count should normalize; persistent elevation after iron repletion would require hemoglobin electrophoresis to exclude thalassemia trait 3

Management Algorithm

Step 1: Obtain iron studies immediately 1

• Serum ferritin and transferrin saturation
• Complete blood count with reticulocyte count

Step 2: If iron deficiency confirmed (ferritin <30 μg/L, TSAT <15-20%): 1

• Initiate ferrous sulfate 325 mg (65 mg elemental iron) 1-3 times daily between meals
• Assess menstrual history for heavy bleeding (most likely cause in 39-year-old female)
• Expect hemoglobin increase of 1-2 g/dL every 2-4 weeks
• Continue iron for 3-6 months after hemoglobin normalizes to replenish stores

Step 3: Recheck CBC after 3 months of iron therapy: 1

• MCV should normalize (80-100 fL)
• Platelet count should decrease toward normal range
• RBC count may remain mildly elevated if thalassemia trait coexists

Step 4: If iron studies are normal or thrombocytosis persists after iron correction: 1

• Refer to hematology for evaluation of thalassemia trait (hemoglobin electrophoresis) or primary bone marrow disorder
• Consider JAK2 mutation testing if thrombocytosis remains >450 × 10³/μL after iron repletion

Common Pitfalls to Avoid

• Do not assume this is "just iron deficiency" without confirming with iron studies—the stability over 4 years does not exclude other diagnoses 1
• Do not rely on MCV alone—iron deficiency can present with normal MCV in early stages, and this patient's MCV of 77.5 is only mildly reduced 1
• Do not ignore the thrombocytosis—while reactive thrombocytosis is common with iron deficiency, persistent elevation after treatment requires investigation 2
• Do not accept ferritin alone if elevated (>30 μg/L)—use TSAT to confirm iron deficiency, as ferritin is an acute phase reactant and can be falsely elevated with inflammation 1

Specific Menstrual Assessment Required

For this 39-year-old female, detailed menstrual history is essential: 1

• Duration of menses (>7 days suggests heavy bleeding)
• Frequency of pad/tampon changes (>1 per hour suggests heavy bleeding)
• Passage of clots larger than a quarter
• This is the most common cause of iron deficiency in premenopausal women and may require gynecologic intervention if severe