How to manage a 39-year-old with anemia and thrombocytosis?

Management of a 39-Year-Old with Anemia and Thrombocytosis

This patient requires immediate investigation for iron deficiency anemia with bidirectional endoscopy (upper endoscopy with duodenal biopsies and colonoscopy), while simultaneously initiating iron supplementation. The thrombocytosis is almost certainly reactive to iron deficiency and will resolve with iron replacement. 1, 2

Immediate Diagnostic Workup

Complete iron studies are mandatory to confirm iron deficiency as the cause of anemia, including serum ferritin, transferrin saturation, serum iron, and total iron-binding capacity. 3, 1 This patient's hemoglobin of 10.2 g/dL meets criteria for investigation in an adult, as guidelines recommend investigating any level of anemia when iron deficiency is present. 3

Gastrointestinal Investigation is Essential

Both upper endoscopy and colonoscopy must be performed regardless of age or symptoms, as gastrointestinal blood loss is the most common cause of iron deficiency anemia in adults outside of menstruation. 1 Even at age 39, this evaluation cannot be deferred:

• Upper endoscopy with duodenal biopsies is required to screen for celiac disease (present in ~5% of IDA cases), gastric cancer, peptic ulcer disease, and angiodysplasia. 3, 1
• Colonoscopy must be performed to exclude colorectal cancer and polyps, as dual pathology (bleeding from both upper and lower GI tract) occurs in 1-10% of patients. 3, 1
• Celiac serology (tissue transglutaminase antibody) should ideally be obtained before endoscopy, but duodenal biopsies should be taken regardless if results are unavailable. 3, 1

Understanding the Thrombocytosis

The platelet count of 496 × 10⁹/L is reactive thrombocytosis secondary to iron deficiency and requires no specific treatment. This is a well-established phenomenon:

• Thrombocytosis is present in approximately 22% of patients with iron deficiency anemia at baseline. 2
• Extreme thrombocytosis (even >1000 × 10⁹/L) can occur with severe iron deficiency and does not indicate a myeloproliferative disorder. 4, 5
• The thrombocytosis will resolve within 3 months of iron replacement therapy in most patients, with platelet counts typically decreasing even in those without baseline thrombocytosis. 2
• No cytoreductive therapy or antiplatelet agents are needed unless there are other clinical indications. 2, 4

Immediate Iron Supplementation

Start oral iron supplementation immediately to correct anemia and replenish body stores, but this does not replace the need for investigation. 3, 1

• Iron therapy should be initiated at presentation, not delayed pending workup results. 3, 1
• Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks; failure to respond suggests continued blood loss, malabsorption, or misdiagnosis. 1
• Continue iron therapy for 3 months after correction of anemia to replenish body stores. 1
• Parenteral iron can be used if oral preparations are not tolerated. 3

Monitoring During Treatment

• Recheck complete blood count at 3-4 weeks to assess response to iron therapy. 1
• Monitor platelet count, which should decrease toward normal range as iron stores are repleted. 2
• If hemoglobin fails to rise appropriately, consider ongoing blood loss, malabsorption (including celiac disease), or incorrect diagnosis. 1

Critical Pitfalls to Avoid

Do not assume the thrombocytosis represents a primary hematologic disorder without first excluding and treating iron deficiency. 2, 4 Initiating unnecessary workup for myeloproliferative neoplasms or starting cytoreductive therapy would be inappropriate and potentially harmful.

Do not delay gastrointestinal investigation waiting for response to iron therapy, as this risks missing time-sensitive diagnoses like malignancy. 1 Iron deficiency in adults warrants investigation regardless of response to supplementation.

Do not attribute the anemia to dietary insufficiency alone without completing the GI evaluation, as occult GI bleeding must be excluded even in younger patients. 3, 1

Avoid transfusion unless the patient has cardiovascular instability, as the hemoglobin of 10.2 g/dL does not typically require transfusion in a stable patient. 3