Common variable immunodeficiency


Common variable immunodeficiency


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USMLE® Step 1 questions

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Common variable immunodeficiency

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USMLE® Step 1 style questions USMLE

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A 13-year-old girl is brought to her pediatricians office for evaluation of shortness of breath and cough. She has had two episodes of pneumonia over the last two years and an episode of bloody diarrhea six months ago requiring hospitalization. Two years ago, the patient was without any significant health complications. Her only past medical history is asthma. Family history is noncontributory. Her immunizations are up to date. Temperature is 38.7 C° (101.7 F°), pulse is 90/min, respirations are 25/min, and blood pressure is 100/60 mmHg. Height and weight are currently at the 5th percentile for age. Physical examination reveals faint rales over the right lower lung field. No enlarged lymph nodes are palpated on neck examination. Laboratory results are shown.

 Laboratory value  Result 
 Complete blood count 
 Hemoglobin  12  g/dL  
 Leukocyte count  10,100 /mm3 
 Platelet count  200,000/mm3 
IgG  250mg/dL 
 IgA  24 mg/dL 
 IgM  15 mg/dL 
 IgE  undetectable 
 CD4/CD8 ratio  2 (normal, 1-4) 

Chest x-ray reveals a right lower lobe infiltrate. Which of the following is the most likely diagnosis in this patient?  

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Common variable immunodeficiency (CVID) p. 114


Common variable immunodeficiency (CVID) is an immune system disorder that impairs your ability to fight infection. It's characterized by low serum levels of all immunoglobulins. People with CVID may present with repeated infections, such as sinus infections, ear infections, pneumonia, and blood infections. They're also at higher risk for other problems, such as autoimmune diseases (diseases where the body mistakenly attacks its tissues), like autoimmune hemolytic anemia, and can also have cancer and gastrointestinal issues. CVID is diagnosed through blood tests through quantitative measurements of the immunoglobulins.


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