WBR0001

Author	PageAuthor::Anonymous (Edited by Will Gibson)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Behavioral Science/Psychiatry, MainCategory::Pharmacology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 23-year-old woman presents to her primary care physician's office with symptoms of depressive episodes, insomnia, and decreased appetite. She also reports episodes of excited mood and euphoria. The patient is referred to a local psychiatrist for treatment of presumed bipolar disorder. After 2 months, the patient returns and reports improvement of her mood swings after she began taking a medication whose name she cannot recall. Unfortunately, she now complains of recent menstrual irregularities, constipation, and fatigue. What medication was likely used to control this patient's bipolar type symptoms?]]
Answer A	AnswerA::Carbamazepine (Tegretol).
Answer A Explanation	[[AnswerAExp::Incorrect: Carbamazepine is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder. It is also the first line treatment for trigeminal neuralgia. Carbamazepine stabilizes the inactivated state of voltage-gated sodium channels, thereby reducing the excitability of neurons. Carbamazepine is an inducer of the Cytochrome P-450 system and adverse reactions to Carbamazepine include rash, SIADH, agranulocytosis and teratogenicity.]]
Answer B	AnswerB::Gabapentin (Neurontin).
Answer B Explanation	AnswerBExp::'''Incorrect:''' Gabapentin is a GABA analogue that inhibits voltage-gated calcium channels. It is used to treat epilepsy, peripheral neuropathy and bipolar disorder. Adverse effects include sedation and ataxia.
Answer C	AnswerC::Venlafaxine (Effexor).
Answer C Explanation	AnswerCExp::'''Incorrect:''' Venlafaxine is an SNRI (inhibits serotonin and norepinephrine reuptake) that is used for depression and generalized anxiety disorder.
Answer D	AnswerD::Amitriptyline.
Answer D Explanation	AnswerDExp::'''Incorrect:''' Amitryptyline is a tricyclic antidepressant.
Answer E	AnswerE::Lithium (Lithobid).
Answer E Explanation	[[AnswerEExp::Correct: Lithium is a mood-stabilizer used to treat bipolar disorder. Its mechanism of action is poorly understood. One of the side effects of lithium is hypothyroidism, which is responsible for the menstrual irregularities, constipation and fatigue in this patient. Further questioning might reveal other manifestations of hypothyroidism such as cold intolerance.]]
Right Answer	RightAnswer::E
Explanation	[[Explanation::This patient has likely been placed on lithium (Lithobid) for mood stabilization, one side effect of which is hypothyroidism. Educational Objective: Lithium is a mood-stabilizer used to treat bipolar disorder; one side effect of Lithium therapy is hypothyroidism. References: First Aid 2012 page 499 Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Bipolar, WBRKeyword::Bipolar disorder, WBRKeyword::Lithium, WBRKeyword::Hypothyroidism, WBRKeyword::Side effect
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::