USMLE USMLE-STEP-3 Online Practice Questions and Exam Preparation

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 61:

  A patient presents with a new neck mass. On examination, she has a palpable thyroid nodule and a palpable cervical lymph node on the same side. Needle biopsy of the thyroid nodule shows amyloid in the stroma.

  The treatment for this patient is which of the following?

  A. total thyroidectomy and modified neck dissection
  B. resection of the involved thyroid lobe, isthmusectomy, and removal of the palpable lymph node
  C. total thyroidectomy and radiation therapy
  D. resection of the involved lobe and part of the contralateral lobe, isthmusectomy, and removal of the palpable lymph node
  E. radioactive iodine administration
  A. total thyroidectomy and modified neck dissection

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  Explanation

  The needle biopsy revealing amyloid makes the diagnosis of medullary thyroid cancer. Patients often present with a neck mass and palpable lymph nodes (1520%). Because of the aggressive nature of the malignancy and the fact that it is often multicentric, total thyroidectomy is the treatment of choice. Modified radical neck dissection is indicated in patients with palpable lymphadenopathy and in patients with tumors larger than 2 cm (since 60% of these patients will have lymph node involvement). Because medullary carcinoma originates from the thyroid C-cells, they do not respond to thyroxine or radioactive iodine therapy.

• Question 62:

  A6-month-old boy is brought to the office for a routine check-up by his mother. They have recently moved to the area and are new to your practice. He is the product of an uncomplicated term pregnancy, has grown and developed appropriately for his age, and is up-to-date on his immunizations. He has had two cases of otitis media in his life. Neither of his parents has been diagnosed with any chronic medical conditions. Both of his parents smoke cigarettes, but "not in the same room" as the child. What information about secondhand smoke could you provide to the parents?

  A. The health risks of secondhand smoke are lower because it has a significantly different chemical composition than directly inhaled tobacco smoke.
  B. Secondhand smoke exposure has been associated with the sudden infant death syndrome (SIDS).
  C. Smoking in another room of the home eliminates the exposure to secondhand smoke.
  D. The amount of carcinogens absorbed by household contacts of smokers is clinically insignificant.
  E. When a cigarette is smoked, most of the smoke is inhaled and very little is released into the environment.
  B. Secondhand smoke exposure has been associated with the sudden infant death syndrome (SIDS).

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  Explanation

  Environmental tobacco smoke, or "secondhand smoke," consists of both "mainstream smoke" which is exhaled by the smoker and "sidestream smoke" which comes from the burning cigarette between puffs. About half of the smoke from a cigarette is sidestream smoke, which consists of the same chemicals as the mainstream smoke that is inhaled by the user. Nonsmokers exposed to secondhand smoke absorb nicotine, carcinogens, and other chemicals from the smoke just as the smoker does. While the concentration of the chemicals absorbed is less than in a smoker, the levels absorbed increase as exposure increases and there are significant health risks involved. The EPAconsiders secondhand smoke to be a class A carcinogen a substance that causes cancer in humans. Among the health risks are increased incidences of asthma, respiratory infections, otitis media, and SIDS in children exposed to secondhand smoke. Nursing mothers can pass harmful chemicals from cigarette smoke in breast milk.

  While separating smokers and nonsmokers in the same airspace may reduce the exposure to secondhand smoke, the exposure is not eliminated. It is estimated to take 3 hours to remove 95% of the cigarette smoke from a room once smoking is completed, so there is still significant risk for exposure even though the nonsmoker is not in the same room. Courts in the United States and Canada have considered the smoking behaviors of parents as factors in determining the "best interests" of a child during custody hearings. Finally, parental smoking is an important predictor of the smoking behaviors of their children as they become adolescents.

• Question 63:

  A 32-year-old male is seen in the ER with a nondisplaced fracture of the ulna after a fall. Incidentally, the intern noticed that the patient is jaundiced and has a palpable spleen. He orders a CBC which shows a Hgb of 10.2 g/dL. The patient reveals that he has chronic anemia and intermittently has been prescribed iron. On further questioning, he says that he had a cholecystectomy at age 23 and that he has family members with similar symptoms. The intern reviews the peripheral smear and finds spherocytes.

  What would be the best way to confirm this man's diagnosis?

  A. splenectomy
  B. Hgb electrophoresis
  C. osmotic fragility
  D. G6PD level
  E. indirect Coombs test
  C. osmotic fragility

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  Explanation

  Hereditary spherocytosis (HS) is a familial hemolytic disorder with clinical features, ranging from an asymptomatic condition to a fulminant hemolytic anemia. The morphologic hallmark of HS is the microspherocyte, which result from membrane protein defects leading to cytoskeleton instability. Spectrin deficiency leads to loss of erythrocyte surface area, which produces spherical RBCs. Spherocytic RBCs are culled from the circulation by the spleen leading to the development of splenomegaly. Spectrin deficiency and the degree of deficiency correlate with the extent of spherocytosis, the degree of abnormality on osmotic fragility test results, and the severity of hemolysis. Hemolysis primarily is confined to the spleen and, therefore, is extravascular.

  Although four abnormalities in red cell membrane proteins have been identified, spectrin deficiency is the most common. Spectrin deficiency results from impaired synthesis, whereas in other instances, it is caused by quantitative or qualitative deficiencies of other proteins that integrate spectrin into the cell membrane. In the absence of these binding proteins, free spectrin is degraded, leading to spectrin deficiency. The major complications are aplastic or megaloblastic crisis, hemolytic crisis, cholecystitis and cholelithiasis, and severe neonatal hemolysis. The classic laboratory features of HS include minimal or no anemia, reticulocytosis, an increased mean corpuscular hemoglobin concentration (MCHC), spherocytes on the peripheral blood smear, hyperbilirubinemia, and abnormal results on the osmotic fragility test. The most sensitive test to help detect HS is the osmotic fragility test performed after incubating RBCs for 1824 hours under sterile conditions at 37. Osmoti c fragility measures RBC resistance to hemolysis when exposed to a series of increasingly dilute saline solutions. The sooner hemolysis occurs, the greater the osmotic fragility of the cells.

• Question 64:

  Use of which medication can result in enamel staining of primary teeth?

  A. erythromycin
  B. ciprofloxacin (Cipro)
  C. cephalexin
  D. trimethoprim/sulfamethoxazole (Septra)
  E. tetracycline
  E. tetracycline

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  Explanation

  Gray or brown teeth staining can be seen with the use of tetracycline in children who still have their primary teeth. Tetracyclines are usually safe as a single course in normal doses in younger children. The use of tetracyclines in children is typically safe after 8 years of age. Teeth staining can also be seen in the children of women who took tetracycline while pregnant.

• Question 65:

  A64-year-old man with hypertension presents for routine follow-up of his blood pressure. His home blood pressure log reveals readings in the 150/70 range. His home monitor had previously been verified by clinic BP readings. He denies any complaints. His current medications include HCTZ 25 mg daily, metoprolol 100 mg twice daily, enalapril 20 mg twice daily, and amlodipine 10 mg daily. He states he is adherent to his medication, drug, and exercise regimen as you recommended. At this time, how would you advise the patient?

  A. You need to take another blood pressure medication.
  B. I need to order some tests to look for secondary causes of high blood pressure.
  C. In spite of your efforts, you need to exercise more and lose more weight.
  D. Your blood pressure is acceptable where it is. Continue your current regimen.
  E. I need to refer you to a cardiologist.
  B. I need to order some tests to look for secondary causes of high blood pressure.

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  Explanation

  Resistant hypertension is defined as blood pressure not at goal despite adequate doses of a three-drug regimen including a diuretic. One of the first considerations is medication compliance and white coat hypertension. White coat hypertension can be assessed by the use of ambulatory blood pressure monitoring. A patient's home monitor should be assessed for accuracy against the office monitor. The patient's technique should also be verified. One should also assess for other agents that may lead to resistant hypertension despite pharmacologic therapy (e.g., tobacco use, NSAIDs, steroids, recreational drugs, oral decongestants, herbal medications). If the above are ruled out, one should initiate a workup to assess for a secondary cause for the hypertension, which may include chronic kidney disease, coarctation of the aorta, Cushing syndrome, steroid treatment, drug-induced hypertension, pheochromocytoma, primary aldosteronism, renovascular hypertension, sleep apnea, and thyroid/ parathyroid disease.

• Question 66:

  A 35-year-old woman presents to your office complaining of fatigue and global achiness. She states that she has "not been myself" since she developed a bad whiplash after a motor vehicle accident. Her health has otherwise been good. About 3 years ago, she saw a cardiologist for chest pain. A full evaluation ensued including heart catheterization that showed no coronary disease, although her cholesterol levels were elevated and a statin was prescribed. She sleeps poorly and notes that she has gained a considerable amount of weight. She has seen a gastroenterologist who has told her that her abdominal pain and alternating constipation and diarrhea are because of irritable bowel syndrome. Physical examination shows that her height is 5 ft 2 in. and her weight is 240 lb. Blood pressure is 126/78. Pulse is 86 and regular. Heart and lung examinations are completely normal. Her pharynx is normal and she has no lymphadenopathy. Abdominal examination shows diffuse mild tenderness, but no masses, rebound, guarding, or organomegaly. Rectal and pelvic examinations are normal. Muscular strength is 4/5 distally and proximally, but there is a considerable give way secondary to pain. She is tender bilaterally at the occiput across the trapezius, iliac crest at the greater trochanteric, anserine bursae bilaterally, and at the second intercostal space bilaterally.

  Reasonable initial evaluations would include which of the following?

  A. electromyogram with nerve conduction studies
  B. muscle biopsy
  C. TSH
  D. Epstein-Barr virus titers
  E. cortisol level
  C. TSH

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  Explanation

  The most likely diagnosis in this case is fibromyalgia. Occasionally, hypothyroidism can present in this way, and a low-grade myopathy can create many of these symptoms. A reasonable workup would include chemistries, TSH, and CPK. The usefulness of Epstein-Barr virus titers in this case is minimal. Epidemiologic studies reveal that about 90% of Americans over the age of 20 have been exposed to Epstein-Barr virus even if they never had a clinical scenario of mononucleosis. Your physical examination did not show any question of acute infectious mononucleosis. Findings of elevated IgG antibodies to Epstein-Barr virus would only reveal the fact that she has had the disease in the past. Absent titers might assure you that there was no evidence of a previous infection, but it is unclear how that would help you sort out the current situation.

• Question 67:

  You see a 31/2-year-old child in the emergency department who has had fever for the past week. The parents relate that their son has some swollen glands, fever, and now seems to be getting a rash on his arms. On examination, you find an uncomfortable appearing young boy whose vital signs are normal with the exception of a temperature of 104. You note t hat he has a red posterior oropharynx with dry, cracked lips. His TMs are normal. He has mild conjunctival injection bilaterally without any discharge.

  His chest is clear, and his heart sounds are normal. He does not have any hepatosplenomegaly. His has a lacy, confluent macular rash on his chest and upper arms, with mild peeling of the tips of his fingers.

  Which laboratory result would be most consistent with the diagnosis?

  A. an elevated platelet count
  B. a positive rapid strep test
  C. a low platelet count
  D. elevated viral IgM titers
  E. a low ESR
  A. an elevated platelet count

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  Explanation

  Kawasaki disease (mucocutaneous lymph node syndrome) is a disease of unclear etiology. The salient diagnostic features include fever for greater than 5 days, cervical lymph node greater than 1 cm, nonpurulent conjunctivitis, oral changes (cracking lips or "strawberry tongue"), polymorphous rash to the trunk, and changes to the hands and feet (peeling of the fingers or toes or edema of the hands or feet). This may be confused with group Abeta-hemolytic streptococcal pharyngitis, which usually is not associated with conjunctivitis. Coxsackie viral infection is commonly seen as the "hand-footmouth" disease, with shallow ulcers on the palms, soles, and in the mouth. There is nominal fever associated, and conjunctivitis is uncommon. Parvovirus B-19 (erythema infectiosum, "fifth disease") is commonly called "slapped cheek" disease because of the exanthem of bright red cheeks. Adenopathy and conjunctivitis are not features of this infection. Acute phase reactions are often elevated late in the course of Kawasaki disease.

  The most common blood test result would be a dramatically elevated platelet count. It is usually greater than 750,000 and can be greater than 1,000,000. An ESR is also likely to be elevated, not low. Apositive rapid strep test would lead one more toward acute GAS disease. The treatment of choice for Kawasaki disease is IVIG and aspirin. IVIG infusion is usually over 12 hours and will commonly result in rapid defervescence and clinical improvement. Treatment of Kawasaki disease is important as it will prevent long-term sequelae. A common side effect of IVIG is aseptic meningitis. Nearly a quarter of untreated children will develop coronary artery dilatation. This is most common cause of acquired heart disease in children younger than 5 years of age. The coronary artery dilatation can result in aneurysm formation and myocardial infarction.

• Question 68:

  A 63-year-old Black female presents to your office complaining of leaking urine. She gets up at night five times to urinate and occasionally loses urine en route to the toilet. During the daytime, she urinates every 45 minutes "to help prevent the leakage." She denies loss of urine with coughing or sneezing. She has not had dysuria or any other pelvic floor complaints. She has a family history of diabetes. She drinks several caffeinated beverages throughout the day. On examination, her postvoid residual urine is normal, and a urine dipstick shows 3+ glucose but is otherwise negative. Her abdominal and pelvic examinations are normal.

  Which of the following do you recommend?

  A. surgery for her incontinence
  B. antibiotics for a UTI
  C. diuretic therapy
  D. timed voids, decrease in caffeine intake, and screening for diabetes
  E. referral to a urologist for cystoscopy
  D. timed voids, decrease in caffeine intake, and screening for diabetes

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  Explanation

  Clinically, this patient is exhibiting signs and symptoms of overactive bladder syndrome, or urge incontinence. Her risk factors include her age, race, caffeine use, and potential abnormal glucose tolerance. Attention should first be directed toward treating any modifiable risk factors. She does not demonstrate findings or a history of stress urinary incontinence for which surgery might be appropriate. Diuretic therapy could worsen, rather than improve, her symptoms, and she does not have findings consistent with a UTI.

• Question 69:

  An 82-year-old woman is admitted to the surgical ward after suffering a fracture of her right hip due to a fall down her stairs. Her surgery and recovery are uneventful, but 3 days later, the nurses are frustrated when she does not let them take her vitals or draw blood. On interview, she exhibits drowsiness with occasional agitation. She is unable to answer questions well and is oriented only to person. She also picks at the empty air and begins yelling and swinging at the nurse who is present. 90.

  An electroencephalogram (EEG) performed on this patient would most likely show which of the following?

  A. diffuse slowing
  B. localized spikes
  C. low-voltage fast activity
  D. random activity
  E. triphasic delta waves
  A. diffuse slowing

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  Explanation

  Explanations: This patient exhibits signs and symptoms of delirium. An EEG is very sensitive for delirium. Localized spikes would be seen in a patient with seizure activity. Random activity is characteristic of the normal, awake state. Lowvoltage fast activity is very specific to delirium secondary to alcohol or sedative/ hypnotic withdrawal. Triphasic delta waves are characteristic of delirious states caused by hepatic failure. All other causes of delirium, however, demonstrate diffuse slowing on EEG. Medications, such as antipsychotics and benzodiazepines, may be helpful in reducing the agitation often seen in delirium. Soft restraints may also be necessary to permit the treatment team to perform appropriate examinations, tests, or procedures and to prevent the pulling out of intravenous access, feeding tubes, and so on. Behavioral interventions may be employed to reinforce orientation to person, place, and time. Some of these interventions may include the use of pictures, lights, clocks, or calendars. The primary and essential approach in the management of patients with delirium, however, is to determine and treat the underlying cause. The presence of a delirium is a poor prognostic sign. The mortality rate for 1 year after a delirium is approximately 50%. The mortality rate for 6 months after an episode of delirium is approximately 25%.

• Question 70:

  A 39-year-old HIV-positive male presents for routine follow-up. He is on highly active antiretroviral therapy. A CD4 count is 250/L. His vital signs are within normal limits and his examination is normal. One month later, a repeat measurement of the patient's CD4 count is 225/L. Which of the following interventions would be the most appropriate at this time?

  A. Continue the current regimen without change.
  B. Modify the patient's antiretroviral therapy to prevent development of resistance.
  C. Discontinue any prophylactic medications that the patient is taking.
  D. Begin azithromycin forM. avium complex prophylaxis.
  E. Recheck CD4 count due to suspected laboratory error.
  A. Continue the current regimen without change.

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  Explanation

  Guidelines for the prevention of opportunistic infections in persons with HIV recommend institution of TMP- SMZ for P. carinii pneumonia prophylaxis when the CD4 count falls below 200 cells/L. Azithromycin or clarithromycin are recommended for M. avium complex when the CD4 count falls below 50 cells/L. All HIV- infected individuals should be tested for IgG antibody against T. gondii as soon as possible after being diagnosed with HIV infection. Counselling should also be provided regarding avoidance of exposure to sources of Toxoplasma. Ganciclovir would be recommended for CMV prophylaxis if there were a history of prior end-organ disease. In a patient with HIV, a PPD is considered positive if there is 5 mm of induration. In a patient with a normal CXR, no symptoms of active disease and no history of treatment for a prior positive PPD, the recommended treatment would be isoniazid for 9 months. In the absence of a suspicious appearing CXR or symptoms, AFB testing would be unnecessary. A booster test would also be unnecessary, as the initial test is already positive. Multidrug therapy would be indicated only for confirmed or suspected active tuberculosis.