We continue on our cytopenias journey, this time talking all about anemia. This is a high yield topic for anyone who sees patients, as this is something we will all see.
Determining the acuity of the anemia is the most important first step.
Acute drop in hemoglobin? Consider active bleeding or hemolysis. Dilutional anemia (a drop in hemoglobin following fluid resuscitation) is also on the differential but should be a diagnosis of exclusion.
Remember that we normally transfuse at a hemoglobin level of 7g/dL. If the patient has active cardiac issues, we transfuse at 8g/dL.
Anemia Severity
> 10g/dL = mild
7g/dL to 10g/dL = moderate
4.5g/dL to 7g/dL = severe, especially if acute
1g/dL to 4.5g/dL = these are almost always chronic if patients are conscious. Think about chronic blood loss or nutritional deficiency.
History: Ask about nutrition, melena, hematochezia. Note that a small amount of blood can change the color of the urine, so beware of contributing rapidly developing anemia to hematuria.
Physical Exam: Check the flanks and thighs for bruising. Feel for an enlarged spleen.
Work Up:
Smear—to evaluate for spherocytes, schistocytes, bite cells, etc.
LDH—will be markedly elevated if blood is actively hemolyzing
DAT/Coombs testing—to screen for AIHA, note that there is a high false positive rate
Type & screen
Haptoglobin—sensitive but non-specific marker for blood breakdown
Reticulocyte count
Macrocytic Anemia: Consider copper, B12, folate deficiency, reticulocytosis. Note that chronic zinc excess can cause copper deficiency.
Microcytic Anemia: Consider iron sequestration or deficiency, lead poisoning, thalassemia.
Normocytic Anemia: Usually multifactorial. Consider low erythropoietin level from chronic kidney disease or early iron deficiency anemia.
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