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NBME 23 Answers

nbme23/Block 2/Question#2

Cyclophosphamide and some other chemotherapeutic ...


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submitted by youssefa(57),

Pathoma: - Lymphocytes are the most sensitive cells to whole body radiation - Granulocytes (Mainly neutrophils) are particularly very sensitive to chemotherapeutic alkylating agents (requiring G-CSF shortly after)

arcanumm  Always think of NEUTROPENIA when chemotherapy is treating rapidly dividing cells (a small fever is an ER visit for these patients). +4  

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submitted by seagull(714),

Another way to approach this is asking yourself which of these cell types are likely undergoing the most mitotic activity. The granulocyte precursors are likely dividing more than nerves or lymphocytes (in absence of infection). This was my approach.

One of the side effects of Cyclophosphamide is myelosuppression.

See full list of side effects below:

Myelosuppression; SIADH; Fanconi syndrome (ifosfamide); hemorrhagic cystitis and bladder cancer, prevented with mesna (sulfhydryl group of mesna binds toxic metabolites) and adequate hydration.

ninja3232  This is incorrect. Myelosuppression can also refer to the lymphocyte lineage. +2  


This question is asking how much reserve capacity there is of each compartment, of which the granulocytes have the least.

Note that myelosuppression can refer to any lineage (including lymphocytes).

ninja3232  This is similar to why sickle cell patients experience aplastic anemia during a parvovirus infection. +  
ninja3232  Sorry, this image is better. https://images.slideplayer.com/37/10733819/slides/slide_5.jpg +  

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submitted by nwinkelmann(185),

Another way to look at: this question is essentially asking what is the MCC side effect of chemotherapeutic agents in general? Answer = bone marrow suppression thus affects granulocytes.