WBR0493

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Immunology
Sub Category	SubCategory::Endocrine
Prompt	[[Prompt::A 24-year-old female presented to her primary care physician for chronic fatigue. She is a graduate student and has always been very active until a few months ago when she started to get tired and sleepy more than usual. The patient reported that she is very sad because she is not as active as usual, and also because she has been gaining weight. The review of system revealed chronic constipation and cold intolerance. Which of the following mechanisms is involved in the patient’s condition?]]
Answer A	AnswerA::Hypersensitivity type I
Answer A Explanation	[[AnswerAExp::Type I hypersensitivity disorders include anaphylaxis, atopy and allergy. Hashimoto's disease is not a type I hypersensitivity disorder.]]
Answer B	AnswerB::Hypersensitivity type II
Answer B Explanation	[[AnswerBExp::Hashimoto's disease is a type IV hypersensitivity disorder. It should not be confused with Grave's disease which is considered a form of type II hypersensitivity because the pathophysiology of Grave's disease involves an antibody against a specific antigen.]]
Answer C	AnswerC::Hypersensitivity type III
Answer C Explanation	AnswerCExp::Hypersensitivity type III disorders include conditions where an antigen-antibody complex forms and activates the complement system. Hashimoto's disease is not a type III hypersensitivity disorder.
Answer D	AnswerD::Hypersensitivity type IV
Answer D Explanation	[[AnswerDExp::Hypersensitivity type IV disorders include conditions characterized by delayed T-cell mediated immune reactions such as contact dermatitis, tuberculosis testing and delayed transplant rejection and Hashimoto's disease.]]
Answer E	AnswerE::Not a hypersensitivity disorder
Answer E Explanation	AnswerEExp::Hashimoto's disease is a type IV hypersensitivity disorder.
Right Answer	RightAnswer::B
Explanation	[[Explanation::The patient's symptoms of fatigue, depression, weight gain, chronic constipation and cold intolerance are suggestive of hypothyroidism. The most common cause of hypothyroidism in this age group is Hashimoto's disease. Hashimoto's disease is caused by anti-TPO and it is considered a form of type III hypersensitivity. Educational Objective: Hashimoto's disease, a cause of hypothyroidism, is a type IV hypersensitivity; whereas Grave's disease, a cause of hyperthyroidism, is a type II hypersensitivity condition. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Hypersensitivity, WBRKeyword::PPD test
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::