Workup for Anemia in a 20-Year-Old with Family History of Colon Cancer
This patient requires immediate comprehensive laboratory evaluation followed by mandatory upper endoscopy and colonoscopy, regardless of the recent pneumonia, because anemia in a young male with family history of colon cancer warrants complete gastrointestinal investigation to exclude malignancy. 1
Initial Laboratory Panel
The workup should begin with the following tests to characterize the anemia and identify its cause:
- Complete blood count with red cell indices (MCV, MCH, RDW) to classify the anemia as microcytic, normocytic, or macrocytic 1
- Reticulocyte count to distinguish between impaired red cell production (low/normal reticulocytes) versus increased destruction or blood loss (elevated reticulocytes) 1
- Iron studies including serum ferritin, transferrin saturation, and total iron-binding capacity—these are essential for diagnosing iron deficiency anemia 1
- Peripheral blood smear to identify morphologic abnormalities not apparent from automated indices 1
- Inflammatory markers (CRP) to assess for anemia of chronic disease or ongoing inflammation from the recent pneumonia 1
Extended Laboratory Evaluation
Additional tests are necessary to exclude other causes:
- Vitamin B12 and folate levels to exclude nutritional deficiencies that can present with normocytic anemia or mask microcytosis when combined with iron deficiency 1
- Renal function tests (creatinine and estimated GFR) to assess for chronic kidney disease 1
- LDH, haptoglobin, and bilirubin if reticulocyte count is elevated, to evaluate for hemolysis 1
Interpreting the Results
Key interpretation points for directing further workup:
- Iron deficiency is diagnosed when serum ferritin is <30 μg/L without inflammation, or up to 100 μg/L with inflammation present, and transferrin saturation <30% 1
- Low or normal reticulocytes suggest impaired erythropoiesis, while elevated reticulocytes indicate increased red cell production from blood loss or hemolysis 1
- Elevated CRP with normal/elevated ferritin suggests anemia of chronic disease from recent infection, but this does not exclude concurrent GI pathology 1
Mandatory Gastrointestinal Investigation
Both upper endoscopy and colonoscopy are mandatory in this patient, regardless of laboratory findings:
- Upper endoscopy with duodenal biopsies to exclude gastric cancer, peptic ulcer disease, angiodysplasia, and celiac disease 1
- Colonoscopy to exclude colonic cancer, polyps, and inflammatory bowel disease 1
- Anemia may be the only presenting sign of asymptomatic colorectal malignancy, and family history increases risk, warranting complete evaluation regardless of age 1
- Right-sided colon cancers are particularly associated with anemia and may present at higher stages 2, 3
Critical Pitfalls to Avoid
Several common errors must be avoided in this clinical scenario:
- Do not assume the anemia is solely from recent pneumonia without excluding GI blood loss, especially with family history of colon cancer 1
- Do not delay investigation because hemoglobin is "only" 10 g/dL—any degree of anemia with iron deficiency warrants investigation in males 1
- Do not skip duodenal biopsies during upper endoscopy, even if celiac serology is negative or not yet available 1
- Watch for combined deficiencies (iron plus B12/folate), which can neutralize each other and result in normal MCV despite significant abnormalities 1
- An extensive laboratory work-up increases diagnostic accuracy compared to routine testing alone 4
Post-Pneumonia Context
While the recent pneumonia may contribute to anemia of chronic disease, this consideration should not alter the workup:
- Recent pneumonia may cause anemia of chronic disease, but GI investigation should not be deferred based on the pneumonia history alone 1
- The temporal association with pneumonia does not exclude concurrent GI pathology that requires urgent evaluation 1
Hematology Referral
- Consult hematology if the cause of anemia remains unclear after comprehensive laboratory workup and GI investigation 1