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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{YD}} (Reviewed by {{YD}})
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pharmacology
|MainCategory=Pharmacology
Line 21: Line 21:
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Gastrointestinal
|SubCategory=Gastrointestinal
|Prompt=A 24 year old male patient presents to the physician’s office with watery diarrhea of several days duration.  Following appropriate work-up, the patient undergoes intestinal biopsy that reveals transmural inflammatory infiltration with granulomatous skip lesions.  The patient is then diagnosed with Crohn’s disease.  The physician wishes to prescribe infliximab.  Which of the following tests must be performed before the initiation of infliximab therapy?
|Prompt=A 24-year-old man presents to the physician’s office with watery diarrhea of several weeks duration.  Following appropriate work-up, the patient undergoes intestinal biopsy that reveals transmural inflammatory infiltration with granulomatous skip lesions.  The patient is then diagnosed with Crohn’s disease.  The physician prescribes infliximab and informs the patient of the benefits and risks of infliximab therapy.  Which of the following tests must be performed before the initiation of infliximab?
|Explanation=[[Infliximab]] is a anti-tumor necrosis factor ([[TNF]]) [[monoclonal antibody]] that inhibits its activity.  Infliximab and other [[TNF inhibitors]] are effective for treatment of [[Crohn’s disease]].  A potential adverse event of [[anti-TNF]] use is the reactivation of [[latent tuberculosis]].  Hence, [[PPD test]] before the initiation of anti-TNF therapy is necessary.
|Explanation=[[Infliximab]] is a anti-tumor necrosis factor ([[TNF]]) [[monoclonal antibody]].  Infliximab and other [[TNF inhibitors]] are effective for the treatment of [[Crohn’s disease]].  A potential adverse event of [[anti-TNF]] therapy is the reactivation of [[latent tuberculosis]].  Accordingly, [[PPD test]] prior to the initiation of anti-TNF therapy is often recommended.  
 
TNF, expressed by [[macrophages]] and [[T cells]], is integral for the development of [[granulomas]] that can limit the reactivation of tuberculosis in immunocompetent patients.  Patients who are on anti-TNF therapy will lose the ability to form granulomas, leading to tuberculous reactivation.
 
[[PPD test]] or [[Mendel-Mantoux test]] is a helpful test in diagnosing latent tuberculosis in individuals who have no signs of active infection.  PPD positivity, however, can also be seen in patients who have received [[Bacillus Calmette-Guerin]] ([[BCG]]) vaccine.


TNF, expressed by [[macrophages]] and [[T cells]], is integral for the development of [[granulomas]] and can limit the reactivation of tuberculosis in immunocompetent patients.  Patients who receive anti-TNF therapy will lose the ability to form granulomas and are at an increased risk of tuberculous reactivation. [[PPD test]] is helpful in diagnosing latent tuberculosis among individuals who have no signs of active infection.  PPD positivity, however, can also suggest a history of [[Bacillus Calmette-Guerin]] ([[BCG]]) vaccine within the past 10 years.
|AnswerA=CD4 count
|AnswerA=CD4 count
|AnswerAExp=CD4 count is important for HIV patients. It is however not pertinent before initiation of anti-TNF therapy.
|AnswerAExp=CD4 count is used to follow-up patients with HIV. HIV testing is not required prior to the initiation of anti-TNF therapy.
|AnswerB=HBsAg
|AnswerB=HBsAg
|AnswerBExp=HBsAg is diagnostic of hepatitis B virus (HBV).  HBV screening is not needed before initiation of anti-TNF therapy.
|AnswerBExp=HBsAg is diagnostic of hepatitis B virus (HBV).  HBV screening is not recommended prior to the initiation of anti-TNF therapy.
|AnswerC=HCV RNA
|AnswerC=HCV RNA
|AnswerCExp=HCV RNA is diagnostic of hepatitis C virus (HCV). HCV screening is not needed before initiation of anti-TNF therapy.
|AnswerCExp=HCV RNA is diagnostic of hepatitis C virus (HCV). HCV screening is not recommended prior to the initiation of anti-TNF therapy.
|AnswerD=Monospot test
|AnswerD=Monospot test
|AnswerDExp=Monospot test is a helpful test for Epstein-Barr virus (EBV).  However, monospot test is not specific and can be positive in other infections and in hematologic malignancies as well.  EBV screening is not needed before initiation of anti-TNF therapy.
|AnswerDExp=Monospot test is a diagnostic test for active Epstein-Barr virus (EBV) infection.  Monospot test, however, is not specific and can be positive in other infections and hematological malignancies.  EBV screening is not recommended prior to the initiation of anti-TNF therapy.
|AnswerE=Mendel-Mantoux test (PPD test)
|AnswerE=PPD test
|AnswerEExp=PPD test or Mendel-Mantoux test is helpful in the diagnosis of latent tuberculosis in a healthy individual.  However, PPD test can also be positive in individuals who have received the Bacillus Calmette-Guerin (BCG) vaccine. Screening for tuberculosis is necessary before initiation of anti-TNF therapy.
|AnswerEExp=PPD test test is diagnostic of latent tuberculosis. Screening for tuberculosis is recommended prior to the initiation of anti-TNF therapy.
|EducationalObjectives=PPD test or Mendel-Mantoux test is helpful in the diagnosis of latent tuberculosis in individuals who have no signs of active infection. Screening for tuberculosis is necessary before initiation of anti-TNF therapy.
|EducationalObjectives=PPD test test is diagnostic of latent tuberculosis. Screening for tuberculosis is recommended prior to the initiation of anti-TNF therapy.
|References=First Aid 2015 page 446
|References=First Aid 2015 page 446.
|RightAnswer=E
|RightAnswer=E
|WBRKeyword=Tuberculosis, PPD, Mendel-mantoux, Infiximab, Crohn disease, Granuloma, Crohn's disease, TNF, TNF-alpha
|WBRKeyword=Tuberculosis, PPD, Infiximab, Crohn disease, Granuloma, Crohn's disease, TNF, TNF-alpha
|Approved=Yes
|Approved=Yes
}}
}}

Revision as of 03:04, 15 August 2015
Author [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pharmacology
Sub Category SubCategory::Gastrointestinal
Prompt [[Prompt::A 24-year-old man presents to the physician’s office with watery diarrhea of several weeks duration. Following appropriate work-up, the patient undergoes intestinal biopsy that reveals transmural inflammatory infiltration with granulomatous skip lesions. The patient is then diagnosed with Crohn’s disease. The physician prescribes infliximab and informs the patient of the benefits and risks of infliximab therapy. Which of the following tests must be performed before the initiation of infliximab?]]
Answer A AnswerA::CD4 count
Answer A Explanation AnswerAExp::CD4 count is used to follow-up patients with HIV. HIV testing is not required prior to the initiation of anti-TNF therapy.
Answer B AnswerB::HBsAg
Answer B Explanation AnswerBExp::HBsAg is diagnostic of hepatitis B virus (HBV). HBV screening is not recommended prior to the initiation of anti-TNF therapy.
Answer C AnswerC::HCV RNA
Answer C Explanation AnswerCExp::HCV RNA is diagnostic of hepatitis C virus (HCV). HCV screening is not recommended prior to the initiation of anti-TNF therapy.
Answer D AnswerD::Monospot test
Answer D Explanation [[AnswerDExp::Monospot test is a diagnostic test for active Epstein-Barr virus (EBV) infection. Monospot test, however, is not specific and can be positive in other infections and hematological malignancies. EBV screening is not recommended prior to the initiation of anti-TNF therapy.]]
Answer E AnswerE::PPD test
Answer E Explanation AnswerEExp::PPD test test is diagnostic of latent tuberculosis. Screening for tuberculosis is recommended prior to the initiation of anti-TNF therapy.
Right Answer RightAnswer::E
Explanation [[Explanation::Infliximab is a anti-tumor necrosis factor (TNF) monoclonal antibody. Infliximab and other TNF inhibitors are effective for the treatment of Crohn’s disease. A potential adverse event of anti-TNF therapy is the reactivation of latent tuberculosis. Accordingly, PPD test prior to the initiation of anti-TNF therapy is often recommended.

TNF, expressed by macrophages and T cells, is integral for the development of granulomas and can limit the reactivation of tuberculosis in immunocompetent patients. Patients who receive anti-TNF therapy will lose the ability to form granulomas and are at an increased risk of tuberculous reactivation. PPD test is helpful in diagnosing latent tuberculosis among individuals who have no signs of active infection. PPD positivity, however, can also suggest a history of Bacillus Calmette-Guerin (BCG) vaccine within the past 10 years.
Educational Objective: PPD test test is diagnostic of latent tuberculosis. Screening for tuberculosis is recommended prior to the initiation of anti-TNF therapy.
References: First Aid 2015 page 446.]]

Approved Approved::Yes
Keyword WBRKeyword::Tuberculosis, WBRKeyword::PPD, WBRKeyword::Infiximab, WBRKeyword::Crohn disease, WBRKeyword::Granuloma, WBRKeyword::Crohn's disease, WBRKeyword::TNF, WBRKeyword::TNF-alpha
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