CPR APPLICATIONS FOUNDATION · CHAPTER 10 · NORMAL
Normal Foundations of Hematology
Organize the chapter before drilling into individual CPR concepts.
Supplemental foundation map: this page orients the detailed CPR Applications for Chapter 10. It is not part of the canonical CPR object inventory.
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Abnormal Foundations
Treatment Foundations
10.1 · SOURCE CPR FOUNDATION
Concept
Hematology is the physiology of a continuously renewing system. Blood cells are produced in marrow, function in circulation, and are cleared by the spleen and liver. Most hematologic disease reflects a problem with production, function, or survival.
Pattern
Step 1 hematology questions are usually classification problems disguised as diagnosis questions. The stem gives CBC patterns, smear clues, bleeding phenotype, or hemolysis markers and expects you to decide whether the problem is marrow output, cell function, or premature destruction/sequestration.
Rule
- Start with production: decide whether one cell line or multiple cell lines are decreased.
- Then assess survival: hemolysis and splenic clearance cause premature loss despite marrow production.
- Then assess function: a normal cell count does not guarantee normal platelet, RBC, or coagulation function.
Applications
- Isolated anemia → RBC-specific production, loss, or destruction
- Pancytopenia → evaluate marrow underproduction, peripheral destruction, and splenic sequestration; multilineage cytopenia does not prove marrow failure
- Mucosal bleeding + normal platelet count → platelet dysfunction
- Anemia + jaundice + hemolysis markers → RBC survival failure
- Tip: Normal cell count does not prove normal cell function.
CPR APPLICATIONS · ACTIVE REASONING
Separate blood-cell output, survival, and function
Choose a response before checking its mechanism. Every worked solution is also available through the expandable explanation if scripts are blocked. Responses are not saved.
Reveal worked reasoning and transfer
Best answer: An increased reticulocyte output. Erythropoietin stimulates marrow red-cell production after blood loss; the rise takes time.
Counterfactual: Why could the initial reticulocyte count remain normal despite serious acute blood loss?
Reveal worked reasoning and transfer
Best answer: Platelet function. Aspirin inhibits platelet cyclooxygenase-1 and thromboxane A2 signaling without necessarily reducing platelet count.
Counterfactual: What does this imply about inferring hemostatic function from platelet count alone?
Reveal worked reasoning and transfer
Best answer: Red-cell destruction or hemolysis. The marker pattern reflects accelerated red-cell destruction, although individual findings need clinical interpretation.
Counterfactual: How would an appropriately raised corrected reticulocyte count support the interpretation?
Change the mechanism
Scenario explanations without scripts
- Low reticulocyte response in anemia: Inadequate marrow compensation is likely; consider substrate lack or marrow disease.
- High reticulocyte response after adequate time: Compensation for destruction or blood loss is plausible.
- Normal platelet count with bleeding: Investigate qualitative platelet, vWF, and other hemostatic defects.
Explain it back: Describe which observation would change the conclusion and why. These are unscored educational exercises, not medical treatment instructions.
How to use this foundation map
- Identify the organizing mechanism.
- Recognize the pattern.
- Restate the rule without looking.
- Test transfer with the applications and question practice.
Pair CPR with the 5P Approach™ when solving cases and questions.