USMLE Step 2 CK

A 28-year-old woman visits her physician complaining of fatigue, palpitations, loss of weight, diarrhea and irritability for 4 months. She is also intolerant to hot weather. She does not smoke or drink coffee or alcohol. Her vital signs are within normal limits except for rapid regular pulse. She has fine tremors and her skin is warm and moist. Her thyroid gland is asymmetrically enlarged and lobulated. Laboratory tests show:

Thyroid stimulating hormone (TSH) 0.02 mu/ml and T4 28 mu/dL

Her physician discusses advantages and disadvantages of all treatment options with the patient.

What is the most important disadvantage of radioactive iodine therapy?

A- Anemia and agranulocytosis

B- Leukemia

C- Ablation of the gland and future hypothyroidism

D- Repeated doses due to repeated failures

E- Acute renal failure

Answer:

Radioactive iodine therapy is the treatment of choice for hyperthyroidism with complications. It leads to ablation of the gland and future hypothyroidism. Patients should be informed before starting treatment of radioactive iodine therapy about the possibility of receiving long life treatment of levothyroxine.

The correct answer is C

A 35-year-old man with a history of Marfan syndrome presents to the emergency room complaining of chest pain radiating to his upper back between shoulder blades. His blood pressure is 170/90 mmHg in his right arm and 90/60 in left arm. His pulse is 98/min. Cardiac examination reveals regular rhythm with diastolic murmur on the left lower sternal border. Lung examination reveals clear bilateral breath sounds. An echocardiogram shows dissection of the thoracic aorta involving the left subclavian artery.

Which of these is the recommended immediate drug of choice?

A- Clopidogrel

B- Heparin

C- Sodium nitroprusside

D- Calcium gluconate

E- Labetalol

Answer:

This is a typical presentation of aortic dissection. Labetalol is an alpha and beta adrenergic antagonist. It is the recommended drug of choice in this case. Sodium nitroprusside is contraindicated as its mechanism of action is dilation of blood vessels which could worsens the case.

The correct answer is E

A 19-year-old man is referred to the clinic for a positive purified protein derivative (PPD) test for tuberculosis. He moved to the United States from Egypt 2 years ago and has been in a good health. He has no history of fever, cough, weight loss or night sweats. He has no family history or contacts with tuberculosis. His physical examination is normal. His chest x-ray shows no cavitation or hilar adenopathy.

What is the appropriate next step in management for this patient?

A- Repeat the PPD test and x-ray after 6 months

B- Start treatment with isoniazid for 9 months

C- Start treatment with multiple drug- antituberculosis therapy

D- Isolation and full antituberculous therapy for 6 months

Answer:

This man has a previous exposure to TB, which caused subclinical infection. His history, physical examination and chest x-ray exclude current active TB. He does not need multiple drug treatment at this time but he should take a prophylactic treatment in case there is any dormant infection in his body. The prophylactic treatment for this case is isoniazid for 9 months.

The correct answer is B

 

A 25 year old woman presents to her physician at 28 weeks of gestation with general itching for one week. Itching is worse at night and more prominent at soles and palms. She has no history of allergy or dermatological diseases. She is compliant with regular examinations and her pregnancy is uncomplicated. Her physical and obstetric examinations are unremarkable. Laboratory tests reveal normal full blood count, renal function tests and blood coagulations tests.

Her liver function tests are as follows:

ALT 47 IU/L

AST 55 IU/L

Alkaline phosphatase 356 IU/L

Total bilirubin 1.9

Bile acids 15 micromol/L

Serology for hepatitis is negative

What is the best treatment for this woman’s itching?

A- Hospitalization and induction of labor

B- Ursodeoxycholic acid and vitamin K

C- Diphenhydramine

D- No treatment and repeat liver function tests in a week

Answer:

This is a case of suspected primary biliary cirrhosis during pregnancy. It is safe to treat this pregnant woman with the routine treatment of primary biliary cirrhosis. Ursodeoxycholic acid and vitamin K is the main course of treatment and is safe for the fetus and the mother.

Correct answer is B

A 64 year-old woman complains of continuous chest pain for 20 minutes. It started suddenly during a stressful meeting. Her pain is dull, aching in nature and 9/10 in severity. She had several episodes of chest pain in the past that starting after exertion and resolving by rest. She was diagnosed with type 2 diabetes and hypertension 8 years ago. Her pulse is 98/min., regular and blood pressure is 160/100. ECG shows T inversion in leads II, III and AVF. Cardiac enzymes are negative. Echocardiography shows no wall motion abnormalities and ejection fraction of 65%.

What is the most appropriate immediate treatment of this patient?

A-Ibuprofen

B-Tissue plasminogen activator (tPA)

C-Enoxaparin

D-Coronary angioplasty

E-Cardiac catheterization

Answer:

This is a case of unstable angina or NSTEMI confirmed by ECG changes, negative cardiac enzymes and echocardiography.  The main course of treatment is anticoagulation as enoxaparin and should be administered as soon as possible. Ibuprofen and other NSAIDs are contraindicated in this case as they increase mortality and morbidity. Thrombolysis as tPA are indicated in elevated ST myocardial infarction. Coronary angioplasty and cardiac catheterization are invasive procedures that not recommended at this time.

The correct answer is C

A 34 year-old man with one week history of sore throat presents today for fever, hoarseness, difficulty breathing and drooling. On physical examination, his temperature is 102.3f and has inspiratory stridor. What is the most preferred next action for this patient?

A-Admit to the intensive care unit

B-Prescribe broad spectrum antibiotic

C-Throat swab and culture

D-Serology for infectious mononucleosis

E-Ultrasonography of the neck

Answer:

This patient most likely has acute epiglottitis with impending airway obstruction. This is an emergency. He needs to be admitted instantly to intensive care unit. H. influenzae is the most common cause of this case. Other options are the steps should be done later after admission to ICU. 

The correct answer is A