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NBME 21 Answers

nbme21/Block 1/Question#1
A 24-year-old woman with sickle cell disease ...
Serum parvovirus B19 IgM antibody test🔍

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 +11  upvote downvote
submitted by jo(19),

Parvo infects RBC precursors in the marrow which can cause aplastic crisis in sickle cell patients.

jo  Infection of precursors halt RBC maturation which leads to giant pronormoblasts with intranuclear viral inclusions in the periphery (UWorld) +8  

 +3  upvote downvote
submitted by temmy(92),

Healthy people who get sick with parvovirus may have a subclinical illness with athralgias as the only symptom. But sickle cell patients and patients with decreases hematopoiesis will develop[ bone marrow failure because the virus affect the hematopoietic stem cells leading to aplastic crises and inability for the bone marrow to adequately compensate hence the low reticulocyte count. parvovirus causes..slapped cheeks in kids hydrops fetalis in fetus, aplastic crises in sickle cell and arthralgias in other patients.

henoch280  thanks. very helpful +  

Parvovirus in adult can mimic presentation of Rheumatoid arthritis (UW).

+1/- b1ackcoffee(8),

 +1  upvote downvote
submitted by spow(15),

To go through the other answers:
A and C) If she had some sort of hemolytic anemia caused by antibodies (i.e. positive Coombs test) or she had hemolysis, her reticulocyte count would be elevated B) No need to do a electrophoresis, you know she has sickle cell E) She has an elevated MCV, so she can't have iron-deficiency anemia

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