USMLE-Rx Step 1 Qmax Challenge #1571

Check out today’s Step 1 Qmax Question Challenge.

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USMLE-Rx Step 1 Qmax Challenge #1571A 13-year-old African American female presents to the emergency department with severe pain in her right hip and back. She has experienced many similar episodes in the past and has a documented history of anemia.

Referring to the graph, if N (the solid curve) is the normal oxygen dissociation curve for hemoglobin, which curve represents the oxygen dissociation curve of the predominant form of hemoglobin in the patient’s blood during this episode?

A. A
B. B
C. C
D. D


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10 thoughts on “USMLE-Rx Step 1 Qmax Challenge #1571”

  1. D
    The blood having a lesser affinity for oxygen binding is represented by a rightward displacement of the curve

  2. D
    This pt most likely has SCD which would decrease affinity (O2’s ability to bind/saturate) and increase pO2 (dissolved oxygen). Answer choice D is the only answer choice showing a right shift.

  3. B
    Patient has SCD with HbF as the predominant Hb. HbF has a high affinity for oxygen leading to a Righ shift in curve.

  4. Ok it’s D* correction
    SCD with decreased O2 affinity (Shift to Right) but still 100% O2 saturation

    and HYDROXYUREA given for SCD management increases HbF(Shift to Left)

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