USMLE USMLE-STEP-2 Online Practice Questions and Exam Preparation

USMLE USMLE-STEP-2 Online Questions & Answers

• Question 251:

  A couple consults you because each has neurofibromatosis and wish to know what their reproductive possibilities are. You should tell them which of the following?

  A. The disease is lethal and results in spontaneous abortion of homozygous fetuses.
  B. 25% of the females will be affected.
  C. 50% of all offspring will be homozygous for the abnormal gene.
  D. 75% or more of their offspring will have the disease.
  E. 25% of their offspring will be unaffected.
  D. 75% or more of their offspring will have the disease.

  ---

  Explanation

  This is an autosomal dominant disorder. Both parents are carriers of the abnormal gene (N), which is on chromosome 17. If each parent is a heterozygote (Nn, where n is the normal gene), 25% of their offspring will have a normal genotype, nn. Fifty percent of their offspring will be affected heterozygotes (Nn), and the remaining 25% will be homozygous affected (NN). If either parent or both are homozygous for the abnormal gene (NN), 100% of the offspring will be affected. As an autosomal disorder, there is no sex predilection; males and females are affected with equal frequency. Prenatal diagnosis is available.

• Question 252:

  A 70-year-old man is brought to his primary care doctor by the man's son. According to his son, who had not seen his father for about a year, the father seemed to have some personality changes. He was no longer interested in his hobbies and seemed apathetic. He seemed to forget easily, and he repeatedly asked the same already answered questions. On at least two occasions, the father wandered out of the house and was found by neighbors, who thought he was confused. If this man had Pick's disease, where would the preponderance of pathology be found?

  A. cerebellum
  B. caudate nucleus
  C. hippocampus
  D. frontotemporal areas
  E. parietotemporal areas
  D. frontotemporal areas

  ---

  Explanation

  Pathologic changes will be seen in the frontotemporal cortex in patients with Pick's disease. Alzheimer's disease, also a cortical dementia like Pick's, has pathologic changes in the parietotemporal areas.

• Question 253:

  For each item, select the ONE best lettered option that is most closely associated with it. Each lettered heading may be selected once, more than once, or not at all. A 35-year-old woman complains of constipation, hair loss, and dry skin.

  A. Cushing's syndrome
  B. Addison's disease
  C. Klinefelter syndrome
  D. hyperparathyroidism
  E. hypothyroidism
  F. pheochromocytoma
  G. acromegaly
  H. diabetes insipidus
  I. diabetes mellitus
  J. polycystic ovarian disease
  E. hypothyroidism

  ---

  Explanation

  The most common symptoms seen in patients with hypothyroidism include tiredness, weakness, dry skin, feeling cold, hair loss, difficulty concentrating with poor memory, constipation, and weight gain.

• Question 254:

  A 10-year-old boy is brought in with a chief complaint of multiple colds. On further questioning, you elicit a history of chronic, clear nasal discharge with no seasonal variation. Other symptoms include sneezing, itching of the nose and eyes, as well as tearing and occasional eye redness. Some relief is obtained with an over-the-counter cold medicine containing antihistamine and a decongestant. His history suggests which of the following?

  A. nasal foreign body
  B. immunologic deficiency
  C. rhinitis medicamentosa
  D. chronic sinusitis
  E. allergic rhinitis
  E. allergic rhinitis

  ---

  Explanation

  The symptoms are suggestive of perennial allergic rhinitis. Causative agents are usually those to which the child is exposed year round, such as house dust, mold spores, or pet danders. Seasonal allergic rhinitis is attributable to sensitization to pollens of trees, grasses, and weeds. Nasal foreign bodies usually result in a foul smelling, unilateral purulent, and occasionally blood tinged, discharge. Recurrent infections may rarely be attributable to immunologic deficiencies. Recurrent pneumonias are the most common complaint. Rhinitis medicamentosa occurs secondary to excessive use of vasoconstrictor nose drops or sprays, resulting in rebound nasal obstruction. Sinusitis is suggested by a bilateral purulent nasal discharge, often accompanied by fever, cough, headache, and sometimes sinus tenderness.

• Question 255:

  In a 6-month-old previously healthy male infant, an abnormality is revealed during a routine diaper change, as illustrated in Figure. The parents have noted this finding on and off on several occasions over the last month. On each occasion, the child has been feeding well, and is content and playful.

  

  Which of the following is the most likely diagnosis?

  A. noncommunicating hydrocele
  B. inguinal adenitis
  C. reducible inguinal hernia
  D. incarcerated inguinal hernia
  E. undescended testes
  C. reducible inguinal hernia

  ---

  Explanation

  This patient has an inguinoscrotal mass from an indirect inguinal hernia. His initial presentation is one of a reducible inguinal hernia. Repair is indicated because of the risk of incarceration. He should be referred for early elective surgery. The second presentation several weeks later is at the time of incarceration of the hernia. This has resulted in pain, irritability, and reflex vomiting. Prolonged incarceration increases the risk of bowel ischemia. The appropriate management is sedation with manual reduction, admission with observation in hospital, and surgical repair within 2448 hours. Delaying repair after an initial episode of incarceration increases the risk of further episodes of incarceration, with potential bowel or testicular compromise. Failure to reduce an incarcerated hernia successfully mandates urgent surgical intervention. Testicular torsion is uncommon in this age group and presents with a tender, high-riding testicle. When suspected, urgent surgical exploration is indicated. Inguinal adenitis may be the result of an inflammatory focus in the diaper area, with resultant adenopathy, and secondary infection of the inguinal nodes with a gram-positive organism. The infant is usually febrile, with a tender inguinal mass. Therapy includes systemic antibiotics. An undescended testicle may present as an inguinal mass, with an empty hemiscrotum. It is usually asymptomatic. Management is elective orchiopexy at approximately 1 year of age. A noncommunicating hydrocele presents as an asymptomatic, fluctuant scrotal mass that transilluminates. Surgical intervention is not required, because most will resolve spontaneously by 1 year of age

• Question 256:

  A 28-year-old man has the acute onset of colicky pain in the left costovertebral angle radiating into the groin, as well as gross hematuria. Abdominal x-ray discloses a stone in the left ureter. Which of the following is true concerning this disease?

  The patient spontaneously passes the stone, which is found to contain calcium oxalate. Which of the following is the most likely cause of this stone?

  A. chronic urinary tract infection
  B. vitamin D excess
  C. primary hyperparathyroidism
  D. idiopathic hypercalciuria
  E. RTA
  D. idiopathic hypercalciuria

  ---

  Explanation

  More than 90% of renal stones are visible on a plain abdominal x-ray, and the majority contain calcium oxalate. Staghorn calculi usually contain magnesium ammonium phosphate (triple phosphate or struvite) and are associated with alkaline urine. This is commonly encountered in chronic urinary tract infections with urea-splitting bacteria. Radiolucent stones often contain urea, which is associated with acidic urine. A small percentage (fewer than 10%) of renal stones contain cystine. The most common cause of calcium stone disease is idiopathic hypercalciuria. Almost half these patients will excrete more than 4 mg of calcium/kg body weight/24 h in the absence of hypercalcemia. Causes of hypercalciuria to be ruled out are sarcoidosis, hyperparathyroidism, and Paget's disease of bone. Idiopathic hypercalciuria is believed to result from either increased GI absorption of calcium, increased calcium resorption from bone, or excessive renal calcium leakage into the urine.

• Question 257:

  A 45-year-old homeless schizophrenic patient presents to you with suicidal ideation. You interview him and find out he is a divorced Roman Catholic. He recently lost his job after being caught a second time drinking on the job. He had attempted suicide impulsively 5 years previous by overdosing. He is not currently psychotic. He bought a handgun and ammunition recently and has been thinking about shooting himself in the head. He has gotten as close to acting on it as having loaded the gun and held it up to his head this morning. Someone walking by stopped him and convinced him to come and see you.

  He is ambivalent about seeking help Which of the following is the most appropriate immediate treatment recommendation?

  A. Start him on antidepressant medication.
  B. Send him home to live with his brother and ask the brother to keep the gun.
  C. Increase his antipsychotic medication.
  D. Prescribe a benzodiazepine to calm him down.
  E. Admit him to the inpatient psychiatric unit.
  E. Admit him to the inpatient psychiatric unit.

  ---

  Explanation

  Most suicides among psychiatric patients are felt to be preventable, as supported by the evidence that inadequate assessment or treatment is often associated with suicide. When to hospitalize patients with suicidal ideation is the most important clinical decision to be made. The absence of a strong support system, a history of past suicide attempt and impulsivity, and having a suicidal plan with intent would be indications for hospitalization.

• Question 258:

  Apatient reports that, on his way to the hospital, he saw a man feeding two squirrels in the park. He says that this means his future will be decided in 2 weeks. This man, he believes, is deliberately out to alarm him (the patient). One of the squirrels is scheming with the man; the other is innocent and trusting. Which of the following terms best describes what this man is experiencing?

  A. illusions
  B. hallucinations
  C. delusions
  D. loosened associations
  E. neologisms
  C. delusions

  ---

  Explanation

  Delusions are false ideas that cannot be corrected by reasoning and that are not based on reality. Psychotic patients often experience ideas or delusions of reference and misinterpret incidents or events in the outside world as having direct personal reference to themselves. Delusions may occur in a variety of psychiatric disorders, including schizophrenia, paranoia, mania, depression, and organic brain syndromes. The bizarre nature of the delusion described in the question is more characteristic of schizophrenia than of other types of psychiatric ailments. Illusions are sensory misperceptions that occasionally may be experienced even by normal individuals. Psychotic persons may report hallucinations, which are sensory experiences that cannot be substantiated by normal observers. Loosened associations and neologisms are patterns of speech often noted in psychotic individuals.

• Question 259:

  A 37-year-old woman telephones to alert her psychiatrist that she has developed a severe pain in her right eye that has persisted for about 5 hours. She has no history of migraine headaches. The psychiatrist is treating her with 150 mg imipramine for major depression. She denies any recent injury or infection in this eye. She wears corrective lenses for nearsightedness. Which of the following is the most appropriate step in management?

  A. Advise her to take an anti-inflammatory analgesic.
  B. Advise her to rest and call again in 8 hour if the pain has not subsided.
  C. Consult immediately with her ophthalmologist.
  D. Plan to evaluate her eye at her next psychiatric appointment in 2 weeks.
  E. Decrease imipramine to 125 mg/day.
  C. Consult immediately with her ophthalmologist.

  ---

  Explanation

  The onset of severe, persistent eye pain is always a cause for concern. In a patient medicated with a drug with anticholinergic side effects, such as imipramine, there is a potential for the development of narrow- angle glaucoma. Adelay in the diagnosis and treatment of this will lead to irreparable harm to the eye. In this case, the psychiatrist would act immediately to facilitate appropriate evaluation and treatment which would best be provided by her ophthalmologist.

• Question 260:

  A62-year-old woman with a long-standing history of diabetes and hypertension presents for evaluation of hyperkalemia. Her room air arterial blood gas (ABG) and electrolytes are the following:

  pH 7.38/PCO2 34/PO2 89 Na 140 Cl 106 BUN 51 K 5.9 CO2 20 Cr 2.8

  Which of the following is the underlying renal abnormality?

  A. renal tubular acidosis (RTA), type 2
  B. focal segmental glomerulonephritis
  C. interstitial nephritis
  D. RTA, type 4
  E. Barter syndrome
  D. RTA, type 4

  ---

  Explanation

  In type 4 RTAassociated with diabetes and hypertension, damage to the juxtaglomerular apparatus in the glomeruli leads to decreased renin production. This results in a state of hypoaldosteronism, causing hyperkalemia and a nongap metabolic acidosis.