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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 621:

  A 6-year-old girl is brought in to the primary care clinic for evaluation by her foster parents, who are concerned that "something is wrong with her." They have noticed odd behavior, with repetitive words and phrases, and difficulty following directions. Her vital signs are normal. Her physical examination is remarkable for a head circumference greater than the 90th percentile but a height less than the 30th percentile, large-appearing ears, and significant flexibility in the joints.

  Which of the following is the most likely comorbid diagnosis in this patient?

  A. anorexia nervosa
  B. ADHD
  C. OCD
  D. oppositional defiant disorder
  E. Tourette disorder
  B. ADHD

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  Explanation

  This patient displays the classic phenotype for fragile X syndrome: a large, long head, long ears, short stature, hyperextensible joints, and macro-orchidism (in males). Cri du chat syndrome involves a deletion affecting chromosome 5 and is characterized by microcephaly, low-set ears, and severe mental retardation. Chromosome 21 is involved in Down syndrome, the most common single cause of mental retardation. Patients with Down syndrome exhibit slanted eyes, epicanthal folds, and a flat nose. Fragile X syndrome results from a mutation on the X chromosome. Fragile X syndrome is the second most common single cause of mental retardation, with affected individuals having mild-to-severe mental retardation. It is also associated with various comorbid diagnoses, including learning disorders, autism, and approximately a 75% rate of ADHD.

• Question 622:

  A 68-year-old widow presents to the primary care clinic for a routine appointment. Her current medical problems include hypertension, obesity, and chronic obstructive pulmonary disease. She has no significant psychiatric history, although she saw a psychologist for eight sessions after her husband died. She does not drink alcohol or use illicit drugs. She has smoked one-and-a-half to two packs of cigarettes per day for the past 45 years and she wishes to quit. She has heard about some of the options but is unsure which would be the most effective.

  Which of the following strategies is most likely to succeed in helping her to quit smoking?

  A. abrupt cessation
  B. behavior therapy
  C. education
  D. medications such as nicotine replacement
  E. medications with group therapy
  E. medications with group therapy

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  Explanation

  The quit rates for abrupt cessation and education/advice are quite low when used alone. The rates increase significantly with behavioral interventions or the use of medications such as nicotine replacement. The highest quit rates are likely seen with the combination of medications plus behavioral therapy such as group therapy. (Synopsis, p. 446) The reinforcing aspects of nicotine addiction are thought to involve the dopaminergic system in the central nervous system. This may be one reason why bupropion, which likely increases dopamine activity, is very effective in helping patients to quit smoking. The other antidepressants listed have not demonstrated efficacy for nicotine dependence.

• Question 623:

  A 72-year-old male presented with nonspecific symptoms of easy fatigability, weight loss, and anorexia. On physical examination, generalized lymphadenopathy and hepatosplenomegaly were present. On the peripheral blood, he was found to have a marked lymphocytosis and in the serum, a small monoclonal spike was present.

  This disease is most prevalent in which age group?

  A. teenagers
  B. 2030 age group
  C. 3040 age group
  D. over 50 years
  E. it may appear at any age
  D. over 50 years

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  Explanation

  Chronic lymphocytic leukemia is a disease that presents generally over the age of 50 with a male predominance. For a long time many of these patients remain asymptomatic and, when they do present, the symptomatology is nonspecific, with generalized lymphadenopathy and hepatosplenomegaly. The peripheral lymphocyte count is generally high and composed of small lymphocytes. A low percentage of patients develop autoantibodies directed against red cells or platelets, which produces autoimmune hemolytic anemia or thrombocytopenia. Although the disease progresses and relapses in spite of the chemotherapy treatment, the overall median survival is 46 years, but this appears to be very variable. Some patients may survive longer than 10 years. All of the parameters for a worse prognosis have to be measured before a final statement of prognosis can be made. The lymph node architecture is diffusely effaced by a population of small lymphocytes, which contain nondiscernible cytoplasm and inconspicuous nucleoli. Mitotic activity is rare, focal proliferation centers with an increase in the number of mitotic activity cells are seen.

• Question 624:

  A 32-year-old woman presents with complaints of irritability, heat intolerance, hyperdefecation, and frequent palpitations. She has lost 20 lb over the past six months. She has always been in good health and does not take any prescription or OTC medications. She denies any prior history of thyroid disease or exposure to head/neck irradiation, but she states that one of her relatives was diagnosed with a thyroid disorder at roughly the same age. Vital signs are as follows: BP 138/78, HR 112, RR 22, temp.

  98.8. On examination, her thyroid is diffusely enlarged and smooth. Auscultation of the thyroid reveals a bruit. Her hair is fine in texture, and she has warm velvety skin. She has hyperactive deep tendon reflexes. There is a fine tremor in her outstretched hands.

  Which of the following interventions is most appropriate at this time?

  A. propylthiouracil
  B. thyroidectomy
  C. radioactive iodine therapy
  D. propranolol
  E. potassium iodide
  A. propylthiouracil

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  Explanation

  This patient's presentation is consistent with Graves' disease. Infiltrative ophthalmopathy is a common finding in this condition. Approximately 2040% of patients with Graves' disease possess clinically evident eye disease. Complaints include photophobia, diplopia, reduced visual acuity, and easy tearing; and, signs of corneal or conjunctival irritation are oftentimes present. Periorbital edema, chemosis, lid retraction with restricted ocular movement, proptosis, and upward gaze impairment may also be found.

  Optic nerve compression may also arise, leading to decreased visual acuity, visual field defects, impaired color vision, and papilledema. Macroglossia, hyperkeratosis, cerebellar ataxia, and pericardial effusion are all findings in hypothyroidism. (Ceci Textbook of Medicine, pp. 13961400) Free T3 levels are elevated in all patients with Graves' disease. Most patients also have elevated free T4 levels, but occasionally this level will remain within the normal reference range in a state known as T3 toxicosis. This generally occurs during the initial phases of Graves' disease or at the onset of a relapse. TSH levels are suppressed by the elevated thyroid hormone levels.

• Question 625:

  A 50-year-old female presents to your office for evaluation of solid food dysphagia without weight loss. Symptoms have been present for 6 months and are progressive. The patient has had two episodes of near impaction, but copious water ingestion and repeated swallows allowed the food bolus to pass. She has never had to present to the ER for disimpaction. She drinks five to six beers per day, loves spicy foods, and smokes a pack of cigarettes daily with a total lifetime history of 30 pack-years. She has had intermittent heartburn symptoms for years and has not sought treatment. She takes hydrochlorothiazide for hypertension. Review of symptoms reveals chronic cough. Physical examination is unremarkable. Upper endoscopy reveals a distal esophageal stricture with inflammatory changes. Esophageal biopsies reveal benign mucosa with chronic inflammation. Gastric biopsies are unremarkable. Helicobacter pylori testing is negative.

  What is the most likely etiology of the patient's stricture?

  A. alcohol ingestion
  B. tobacco use
  C. gastroesophageal reflux
  D. hydrochlorothiazide
  E. spicy food ingestion
  C. gastroesophageal reflux

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  Explanation

  The patient has a peptic stricture, seen in the setting of long-standing untreated gastroesophageal reflux with esophagitis. The history of progressive solid food dysphagia without weight loss is typical. Tobacco, alcohol, thiazide diuretics, and spicy foods do not predispose to benign esophageal strictures. The patient has developed a peptic stricture, a serious complication of GERD. The patient needs esophageal dilation (either with mechanical or pneumatic dilators) and maximal acid suppression. PPI therapy is superior to histamine receptor antagonist therapy in terms of healing erosive esophagitis. Patients with long-standing GERD are at increased risk of developing Barrett esophagus, a risk factor for esophageal adenocarcinoma. GERD is not a risk factor for esophageal squamous cell cancer, gastric cancer, or duodenal cancer. Patients with chronic H. pylori infection (which this patient did not have) are at increased risk for a form of gastric lymphoma known as a MALT-oma.

• Question 626:

  An 82-year-old woman schedules an appointment to see you for neck and back pain. At age 50, she had an L4-L5 diskectomy and laminectomy. She also has long-standing hypothyroidism for which she takes levothyroxine 0.1 mg daily. Over the past few months, she has become more fatigued and describes pain in both of her arms, her low back, and the front of her thighs. She notes that the tops of her shoulders are also achy. She decided to call for an appointment because of worsening headache. She tells you that she has an appointment later this afternoon with her ophthalmologist, because she noticed some flickering of the vision in her left eye. Upon further questioning, she does acknowledge that she has cut her telephone conversation short with her daughter because her jaw begins to ache if she talks too long. Physical examination shows that she has normal vital signs. She has diffuse scalp tenderness. The oral mucosa is normal without aphthous ulcers and the salivary pool is normal. Her pupils are equal, round, and reactive to light and accommodation, and extraocular muscles are intact. The funduscopic examination appears normal for her age. Neck motion is slightly reduced to lateral flexion and rotation. Her trapezii are tender to palpation, but there is no significant loss of range of motion in her shoulders. Her supraspinatus and infraspinatus tendons appear intact. Her quadriceps are mildly tender, but her gastrocnemius muscles are normal. Her strength is normal for age. Her reflexes are normal and symmetrical.

  The most likely diagnosis is which of the following?

  A. polymyalgia rheumatica
  B. osteoarthritis of the cervical spine
  C. osteoarthritis of the lumbar spine
  D. bilateral rotator cuff tears
  E. temporal arteritis
  E. temporal arteritis

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  Explanation

  The diagnosis is almost certainly temporal arteritis. Age over 70, headache with scalp tenderness, jaw claudication, and visual disturbance would suggest the diagnosis even if the sedimentation rate came back within the normal range. Since the patient's supraspinatus and infraspinatus strength are normal, complete rotator cuff tear seems unlikely. Rotator cuff tears would also not explain the leg component. Osteoarthritis of the neck and back could explain many of her clinical features, particularly if spinal stenosis is present, but would not account for the jaw claudication or the headaches with scalp tenderness. Many patients with temporal arteritis have features of polymyalgia rheumatica, but in this case, temporal arteritis is the best working diagnosis.

  Temporal arteritis is one of the few unequivocal rheumatic disease emergencies. The patient should be given large doses of prednisone immediately. An ESR should be obtained, but as noted above, even a normal study would not prevent the prednisone from being prescribed at this point. You should also contact the ophthalmologist because there can be retinal clues not picked up on standard office funduscopy. In addition, many ophthalmologists now will do the temporal artery biopsy in their patients. This is a very reasonable next step for the patient and will unequivocally establish the diagnosis.

  Temporal arteritis may have skip lesions, and thus, a fairly significant length of the temporal artery should be taken by the surgeon. MRI of the brain, even with MRA, will not help establish a diagnosis of temporal arteritis and will needlessly delay diagnosis, possibly causing the patient to lose vision.

• Question 627:

  A 54-year-old male presents to the ED with acute onset of severe abdominal pain. His history is significant for gnawing epigastric pain that radiates to the back for several months. Physical examination demonstrates mild hypertension and tachycardia as well as a rigid "board like" abdomen with generalized rebound tenderness and hypoactive bowel sounds. Rectal examination reveals dark hemoccult positive stools without gross blood.

  Which of the following would be the next appropriate step in management?

  A. order upright chest and abdomen x-rays
  B. obtain a CT scan of the abdomen and pelvis
  C. plan for upper GI endoscopy
  D. take patient to the OR for immediate exploratory laparotomy
  E. schedule the patient to be seen in surgery clinic in 1 week
  A. order upright chest and abdomen x-rays

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  Explanation

  The patient's history of gnawing epigastric pain is consistent with ulcer disease. His presentation is that of a perforated duodenal ulcer. The most appropriate first step is to obtain upright plain films of the chest and abdomen to look for free intraperitoneal air. Although the patient is in mild distress, he is not toxic and it is reasonable to confirm your suspicion with radiologic studies. If the plain films did not demonstrate free air and the patient remained hemodynamically stable, a CT scan of the abdomen and pelvis may be indicated to try to make the diagnosis. However, if the patient did show signs of increasing toxicity and evidence for sepsis, such as hypotension or mental status changes, it would be reasonable to proceed with an exploratory laparotomy to make the diagnosis. Upper endoscopy is not indicated in the acute management of a perforated duodenal ulcer and this patient is currently in significant distress and discharging to home with delayed follow-up is unwise. The patient most likely has a posterior perforation of a duodenal ulcer that has eroded into the gastroduodenal artery causing bleeding per rectum, tachycardia, and hypotension. Diverticulosis is a common cause of bright red blood per rectum in elderly patients but is often painless and not consistent with the presentation of this patient. A ruptured AAA generally presents with hypotension and profound shock. A distended abdomen and pulsatile mass can be found on physical examination. Ruptured esophageal varices present with upper GI bleeding and hematemasis and are most often associated with patients who have chronic liver disease.

• Question 628:

  A 64-year-old male has been suffering from lower back pain for over 10 years. You have been following him for this period. You have prescribed stretching exercises and, occasionally, an anti- inflammatory medication to alleviate his pain. Although he has had no neurologic deficits in the past, today he has shown up in your office unexpectedly, complaining of bilateral lower back pain with numbness and tingling over the dorsal aspect of both feet. His symptoms have become progressively worse over the past 2 weeks and he is now unable to stand for more than 5 minutes without developing extreme pain and numbness. His symptoms are much improved by sitting down or kneeling over a chair. Climbing stairs seems to be tolerated well, but walking greatly exacerbates the pain. He denies bladder or bowel incontinence or retention, point tenderness or anesthesia in the lower back along the spinal cord or in the saddle area.

  What is the likely diagnosis?

  A. spondyloathropathy of the sacroiliac joint
  B. age-related early degenerative joint disease (DJD) of the hips
  C. spinal stenosis of the lumbosacral area
  D. muscle spasm of the lower back
  E. cauda equina syndrom
  C. spinal stenosis of the lumbosacral area

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  Explanation

  Although all of the given diagnoses could produce similar symptoms, there are distinct findings which suggest a diagnosis of spinal stenosis. Spinal stenosis is a degenerative disorder of the spine which normally presents after the age of 50. Neurologic symptoms, including dysesthesias and paraesthesias, and pain are often bilateral and not localized, since it commonly affects multiple vertebrae. The symptoms are improved with flexion of the spine (sitting or climbing stairs) and worsened by straightening the spine (standing). There is no localized pain in the sacrum and no bowel or bladder incontinence, so a diagnosis of cauda equina syndrome or spondyloarthopathy is less likely. Muscle spasms and early DJD should not produce such neurologic findings. The most sensitive and specific imaging study in the diagnosis of spinal stenosis, among those given above, is an MRI of the spine at the affected area. Although x-rays of the spine have been frequently used in the past in the evaluation of lower back pain, they have been shown to be of limited value in diagnosing pathology. Bone scans may detect malignancy or infection before radiography does, but are of no value in spinal stenosis. Indium scans would be useful in occult inflammatory pathology and nerve conduction studies would suggest a neuropathic deficit, but would not help in localizing the defect.

• Question 629:

  A 29-year-old married male is seen in the emergency room with the chief complaint of, "I'm afraid I'm having a heart attack." He states a 2-month history of experiencing recurrent episodes of chest pain and shortness of breath that last 1020 minutes. He also describes associated tachypnea, lightheadedness, tingling in his extremities, nausea, diaphoresis, anxiety, and fears that he may die. These symptoms are now occurring almost daily but are not provoked by any situations or activities such as exertion or exercise. He is significantly worried about having future episodes and is genuinely concerned that he will suffer a myocardial infarction. He denies having any medical illnesses or taking any medications. He drinks three beers on the weekends only and does not use illicit drugs. His physical examination reveals a slightly elevated BP and pulse. An ECG demonstrates sinus tachycardia

  Which of the following medications would be most appropriate in the long-term management of this patient's symptoms?

  A. bupropion
  B. buspirone
  C. imipramine
  D. lorazepam
  E. paroxetine
  E. paroxetine

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  Explanation

  This patient is most likely experiencing panic attacks as part of panic disorder. Dopaminergic antidepressants such as bupropion have not demonstrated significant efficacy in panic disorder. Buspirone is approved in the treatment of GAD but is not useful in panic disorder. While tricyclic antidepressants, such as imipramine, and SSRIs, such as paroxetine, are both effective in the treatment of panic disorder, therapeutic benefit for both may require several weeks. Benzodiazepines, such as lorazepam and alprazolam, have been shown to be effective in the treatment of panic disorder. Their more rapid onset of action (hours to days) make them ideally suited for the immediate and acute management of panic attacks. Neither bupropion nor buspirone are considered to be first-line treatments for panic disorder. Imipramine and other tricyclic antidepressants have demonstrated their efficacy in panic disorder. The disadvantages are several: the need to increase up to a therapeutic dose over time, a significant side effect profile, and lethality in overdose. While benzodiazepines such as alprazolam are also effective in the long-term treatment of panic disorder, their potential for abuse and withdrawal if/when tapered make them less than ideal overall. It is not unusual to initiate a benzodiazepine for more immediate relief of anxiety along with another agent that will require a longer time period until its benefits become apparent. Given their proven efficacy, reduced side effects, lack of abuse potential and safety in overdose, SSRIs such as paroxetine are the most suitable choice for the long-term pharmacotherapy of panic disorder.

• Question 630:

  A 64-year-old male with a history of hypertension and tobacco abuse presents for follow-up after a routine physical during which he was found to have 45 red blood cells (RBCs) per high-power field (HPF) on a screening urinalysis. The urinalysis was negative for leukocytes, nitrites, epithelial cells, and ketones. The patient denies any complaints and the review of systems is essentially negative.

  In detecting microscopic hematuria, which of the following is true?

  A. The office urine dipstick is 91100% sensitive and 6599% specific for detection of RBCs, Hgb, and myoglobin.
  B. Urinalysis must reveal a minimum of 5 RBCs per HPF in order to continue the workup.
  C. The presence of epithelial cells makes the urinalysis invalid.
  D. The presence of "large blood" on a urine dipstick effectively distinguishes RBCs from myoglobinuria.
  E. Any urinalysis with RBCs should be recollected via a catheterized specimen prior to initiating a workup for hematuria.
  A. The office urine dipstick is 91100% sensitive and 6599% specific for detection of RBCs, Hgb, and myoglobin.

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  Explanation

  Asymptomatic microscopic hematuria is defined by the American Urological Association as three or more RBCs per high power field on urinary sediment from two out of three properly collected urinalyses. A proper sample can be a midstream clean-catch specimen. The urine dipstick is roughly 91100% sensitive and 65- 99% specific for detection of RBCs, Hgb, and myoglobin. Urine dipstick is not reliable in distinguishing myoglobin from Hgb or RBCs. Therefore, urinalysis with microscopy should be ordered to assess the number of RBCs per high power field. Microscopic hematuria is usually an incidental finding but deserves a thorough workup, as 10% can be due to malignancy. The initial approach is to repeat the urinalysis to rule out infection. If the urinalysis suggests infection by the presence of WBCs or nitrites, a culture should be ordered and the patient treated appropriately. If RBCs are present without any leukocytes, nitrites, or epithelial cells on the repeated urinalysis, a proper workup should ensue.

  After history and physical are done to rule out risk factors, comorbidities, or other etiologies to account for the hematuria, one must look to diagnostic tests. A serum creatinine is useful to assess for renal insufficiency. During the course of the workup, if the urinalysis and serum creatinine suggest a glomerular etiology (casts, elevated creatinine, dysmorphic RBCs) a renal consultation and possible renal biopsy may be warranted. Evaluation of the upper tract with either an IVP or CT scan of the abdomen/ pelvis with and without contrast should be ordered to rule out renal cell carcinoma, nephrolithiasis, or aneurysms. Next, the lower tract should be visualized by cystoscopy and washings sent for cytology. If all the above workup is negative, the patient can be reassured and followed with a repeat urinalysis in 6 months.