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

USMLE USMLE-STEP-3 Online Questions & Answers

• Question 391:

  A 63-year-old Native American male, with a 6-year history of DM, hypertension, and hyperlipidemia, comes to your office as a new patient for a routine examination. He has been experiencing frequent lower back pain and headaches for which he is taking ibuprofen daily for the past 5 weeks. Moreover, he is complaining of mild fatigue. In addition, he is taking aspirin, atorvastatin, verapamil, and glipizide. His physical examination shows a blood pressure of 165/80 and heart rate of 90 bpm. In general, he was not in any distress. His funduscopic examination reveals no signs of diabetic retinopathy. Cardiac examination reveals a regular rate and rhythm with an S4 gallop. His lungs are clear and abdominal examination is unremarkable without any bruit auscultated. He also has 2+ lower extremity pitting edema. Rectal examination reveals brown stool, negative for occult blood. His laboratory results are as follows:

  

  Which of the following is a typical finding in this patient's condition?

  A. hypocalcemia
  B. macrocytic anemia
  C. elevated thyroxine levels
  D. hypocomplementemia
  E. hematuria
  A. hypocalcemia

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  Explanation

  This patient's presentation and laboratory data are consistent with nephrotic syndrome. Nephrotic syndrome is typically associated with proteinuria of greater than 3.5 g/day, hypoalbuminemia, edema, and hyperlipidemia. Abnormalities commonly seen in nephrotic syndrome include hypocalcemia (due to vitamin D deficiency), low thyroxine levels (due to loss of thyroxine-binding globulin [TBG]), and microcytic, hypochromic anemia (due to transferring loss). Hypocomplementemia may be found in some forms of nephrotic syndrome, but this is not a typical finding. Hematuria is one of the components found in nephritic syndrome.

  This patient has history, physical, and laboratory findings that suggest possible multiple myeloma. For example, his history is pertinent for lower back pain and headaches. Moreover, Bence-Jones protein is not usually detected by urine dipstick but will be detected during a 24-hour urine collection. This would explain why there is relatively little urine protein detected on dipstick but over 5 g on the 24-hour urine. Lastly, multiple myeloma should be considered in an older patient with unexplained anemia. Given these findings, a serum and urine protein electrophoresis would be the best test to order next. A kidney biopsy would usually be diagnostic, but is unnecessary if the electrophoresis is positive. Complement levels and anti- GBM titer would not be of any use at the present time. Checking glycosylated Hgb will inform you of the adequacy of glucose control, but will be of little use with regard to the workup of the nephrotic syndrome. This patient has a low anion gap due to the presence of unmeasured cations in the blood. In this case, they arise from circulating immunoglobulins. The fractional excretion of sodium and urea can be helpful in differentiating prerenal causes from other etiologies of acute renal failure. A split 24-hour urine for protein is helpful in determining the presence of orthostatic proteinuria. Initiation of ACE inhibitors or angiotensin receptor blockers is the best option in patients with diabetic nephropathy, as these medications have been shown to slow the progression of kidney disease. The other medications listed may be used adjunctively, with an ACE inhibitor or angiotensin receptor blocker, if adequate blood pressure control could not be achieved with monotherapy. HIV-associated nephropathy is typically associated with a collapsing glomerulopathy, a variant of focal segmental glomerulosclerosis. Membranous nephropathy is associated with a number of other infections, including syphilis, hepatitis B, and hepatitis C virus. Membranoproliferative glomerulonephritis has also been associated with hepatitis C virus.

• Question 392:

  The patient is a 70-year-old man brought to the primary care clinic by his family over concerns that he has Alzheimer's disease. They have noticed a worsening of his memory over the past 6 months. He does not seem to want to get out of bed, and he appears to have difficulty providing for his basic needs such as cleaning, dressing, and cooking for himself. He is hesitant when talking, but it is unclear whether he is unable or unmotivated to speak. His family has also noticed that he appears depressed and is often seen crying. A MSE of the patient is performed to help determine whether he is suffering from a dementing illness or a depressive illness (pseudodementia).

  Further history, cognitive examinations, physical examination, and laboratory/radiographic studies are obtained. The results are consistent with Alzheimer's dementia. While the family had been able to take care of him initially, they have since returned to the clinic stating that they can no longer keep him at home. They feel that he is becoming much more agitated. He is staying up at night. Lately he has been rearranging the furniture, claiming to look for "the little people who are teasing me." They have noticed that he has difficulty walking, often moving slowly and dropping items. The family has pursued nursing home placement, but they wish to have something prescribed in order to help him sleep and keep him calm.

  Which of the following medications should be avoided in this patient?

  A. buspirone (Buspar)
  B. donepezil (Aricept)
  C. lorazepam (Ativan)
  D. trazodone (Desyrel)
  E. risperidone (Risperdal)
  E. risperidone (Risperdal)

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  Explanation

  Older patients with cognitive decline due to depression, sometimes called pseudodementia, display characteristic findings on MSE. They usually are greatly concerned about their problems, even emphasizing their difficulties when compared with demented patients, who attempt to hide or minimize their deficits and appear unconcerned. Patients with pseudodementia are able to attend well to tasks despite their cognitive complaints. Individuals with dementias, however, have significant difficulty with attention and concentration. Patients with depression are more likely to demonstrate good insight into their presumed memory loss than those with dementia, who will commonly deny that there is anything wrong with them. On tests of cognition, those individuals with pseudodementia will show inconsistent results, performing better at some times and worse at others. Patients with dementia, however, will consistently perform poorly on various tests that address the same function. This patient displays characteristics of Lewy body disease, a dementia which may be related to Alzheimer's dementia. The classic triad of Lewy body dementia is a fluctuating course, peduncular hallucinations (visual hallucinations of small people, animals, or objects), and parkinsonian features. These patients tend to be very sensitive to extrapyramidal side effects and, therefore, antipsychotics such as risperidone should be avoided or sparingly used.

• Question 393:

  A 60-year-old Asian male presents with early satiety and 40-lb weight loss over 3 months.Upper endoscopy shows an irregular mass in the antrum of the stomach. What can you tell him and his family about his situation?

  A. Weight loss indicates distant metastases, and surgical resection is not indicated.
  B. Antral tumors have a worse prognosis than tumors at other sites in the stomach.
  C. CT is the most effective imaging modality for determining TNM (tumor, nodes, and metastases) stage.
  D. 5-year survival for patients with gastric adenocarcinoma confined to the mucosa with no nodal metastasis approaches 90%.
  E. Chemotherapy is an effective treatment modality in stage IV gastric adenocarcinoma, with significant benefit in overall survival.
  D. 5-year survival for patients with gastric adenocarcinoma confined to the mucosa with no nodal metastasis approaches 90%.

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  Explanation

  Gastric adenocarcinoma is associated with dismal overall prognosis, with long-term survival seen only in patients with early stage disease. Surgical resection remains the mainstay of potentially curative therapy, with poor responses to chemotherapy in the majority of clinical trials. Patients often present with vague epigastric discomfort, occult GI bleeding/anemia, anorexia, weight loss, and even hematemesis/ vomiting. Patients are staged with endoscopic ultrasound, which is the most effective imaging modality for determining T and N stage. CT may also be useful for determining nodal metastases, but is more accurate for determining distant metastases (liver). Antral tumors may have a better prognosis than more proximal gastric tumors, with a decreased incidence of nodal metastases. Five-year survival rates for stage I disease is excellent, approaching 8090% in both the Western countries and in Asia. However, 5-year survival rates are dismal for stage III and stage IV disease, and most Western series report overall 5-year survival rates for gastric cancer of 1021%.

  In contrast to gastric adenocarcinoma in the United States, the incidence of gastric lymphoma is rising. Gastric lymphoma accounts for two-thirds of GI lymphomas. Symptoms are similar to gastric adenocarcinoma, but obstruction, perforation, and massive bleeding are very uncommon symptoms. Because gastric lymphoma spreads by submucosal infiltration, mucosal biopsies at the time of upper endoscopy can often be nondiagnostic. Repeated biopsies to obtain submucosal tissue are needed to establish a diagnosis. Treatment protocols vary among institutions, but most often center on chemotherapy; surgical resection of isolated or localized gastric lymphoma can be curative, but is rarely seen. Fortunately, survival rates for gastric lymphoma are much better than those seen in gastric adenocarcinoma, with cure rates of 70% seen in patients with stage IE and IIE disease treated with chemotherapy alone.

• Question 394:

  A healthy 38-year-old G4P3003 presents for amniocentesis. The karyotype returns as shown in the Figure You counsel the patient that which of the following was likely her biggest risk factor for the development of this karyotype?

  

  A. cigarette smoking
  B. lack of folic acid supplementation
  C. maternal age at conception
  D. family history
  E. alcohol consumption
  C. maternal age at conception

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  Explanation

  Down syndrome is a trisomy of chromosome 21. It is the most common nonlethal trisomy. Patau syndrome is trisomy 13 and Edwards syndrome is trisomy 18. Turner syndrome is 45 X, a monosomy. Klinefelter syndrome is the presence of an extra X chromosome in a male resulting in 47 X-X-Y. Down syndrome is the most commonly recognized genetic cause of mental retardation. The risk of trisomy 21 is directly related to maternal age as a result of maternal nondisjunction. The risk of having a child with Down syndrome increases in a gradual, linear fashion until about age 30 and increases exponentially thereafter. Women who will be 35 years or older at the time of delivery should be offered chorionic villus sampling or secondtrimester amniocentesis. Women younger than 35 years should be offered maternal serum screening at 1618 weeks of gestation. The maternal serum markers used to screen for trisomy 21 are alpha-fetoprotein, unconjugated estriol, and hCG. The use of ultrasound to estimate gestational age improves the sensitivity and specificity of maternal serum screening

• Question 395:

  A woman complains of amenorrhea for several months following a dilation and curettage.

  Which of the following is the most likely reason?

  A. occult perforation of uterus during the procedure
  B. intrauterine scarring
  C. infection of the endometrium (endometritis)
  D. iron-deficiency anemia from blood loss during the procedure
  E. premature menopause
  B. intrauterine scarring

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  Explanation

  Asherman syndrome describes intrauterine synechiae (scarring) of the uterine cavity following a surgery of infection of the uterine endometrium. Asherman syndrome is seen following uterine surgery (such as a uterine curettage or myomectomy), septic abortion, or other endometrial cavity infection. The damaged endometrium scars together lead to impairment of the endometrial function. This may result in amenorrhea, dysmenorrhea, infertility, or miscarriage. If the scarring causes obstruction of outflow of menstrual tissue, then hematometra and dysmenorrhea can occur. Severe scarring leads to complete obliteration of the uterine cavity

• Question 396:

  A 48-year-old woman presents for evaluation of progressively worsening dyspnea. She relates the onset of symptoms to a "walking pneumonia" that she had a year ago. Her breathing has worsened progressively since that time. She has a "smoker's cough" productive of some clear or white phlegm, for which she frequently sucks on cough drops. She started smoking regularly at the age of 18. She currently smokes about a pack of cigarettes a day, down from as much as two packs per day. She is not on any medications regularly. She has no history of heart disease and has always had normal blood pressure.

  Which of the following physical examination findings are you most likely to find in this patient?

  A. prolonged expiratory phase of respiration
  B. supraclavicular adenopathy
  C. rales one-quarter of the way up in both lungs
  D. clubbing of fingers
  E. prominent first heart sound
  A. prolonged expiratory phase of respiration

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  Explanation

  COPD is a group of chronic and progressive pulmonary disorders that cause reduced expiratory flow. Most of the obstruction is fixed, although some reversibility can be found. COPD affects approximately 16 million Americans and smoking is, by far, the greatest risk factor. Onset is typically in the fifth decade and the typical presenting symptoms are dyspnea and cough. Patients often relate these to an acute illness (walking pneumonia in this case) but the decline in pulmonary function has been present for some time prior to the onset of symptoms. The physical examination has poor sensitivity and may, in early disease, only show wheezing on forced expiration and a prolonged expiratory phase of respiration. Clubbing is not typically a manifestation of COPD and its presence should lead to a search for another cause, such as lung cancer. In the setting of pulmonary hypertension, sometimes one can hear a pronounced pulmonic component to the second heart sound, although hyperinflation may obscure this finding. Bilateral pulmonary crackles would be more consistent with pulmonary edema. Supraclavicular adenopathy should lead to a workup to exclude cancer, especially of breast, lung, ovarian, or GI origin. Hyperinflation of the lungs is the most likely CXR finding in this case. This would manifest as flattened diaphragms with elongated lungs and a long, narrow cardiac shadow. Kerley B lines would be more characteristic of pulmonary edema from left-sided heart failure, rather than COPD. A pulmonary mass with adenopathy would be more consistent with lung cancer--certainly a possibility in a long-time smoker, but much less common than COPD. A residual infiltrate from pneumonia a year ago would be highly unlikely.

• Question 397:

  A 39-year-old woman presents to the office for the evaluation of a mole on her left arm. It has been present and enlarging over the past 6 months. It itches and occasionally bleeds. Which of the following attributes would be considered high risk for skin cancer?

  A. diameter of greater than 6 mm
  B. a sharply demarcated, regular border
  C. a uniform coloration
  D. a symmetric, circular shape
  E. a flat lesion
  A. diameter of greater than 6 mm

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  Explanation

  The mnemonic "ABCDE" is often used to remember some of the attributes of skin lesions that would make them more suspicious for being malignancies. "A" is for asymmetry; "B" for border that is irregular or indistinct from the surrounding skin; "C" for color such as dark black or variations in colors within the same lesion; "D" for diameter greater than 6 mm, or larger than the size of a pencil eraser; "E" for elevation of The presence of a diameter of greater than 6 mm would be lesion with surface irregularity.

  Of the choices considered a higher-risk attribute. Primary skin malignancies are divided into three major categories--basal cell carcinoma, squamous cell carcinoma, and melanoma. Basal cell carcinomas may grow large and be locally destructive, but they have the lowest metastatic potential of the three types of skin cancer. Basal cell carcinomas are more common in persons with fair complexions but they occur in all skin types and colors. Squamous carcinomas of the skin have a metastatic potential greater than basal cell carcinomas and less than malignant melanomas. Squamous carcinomas most commonly occur in sun-exposed areas but are also associated with other etiologies, such as human papilloma virus (HPV), and can occur anywhere on the body.

  Malignant melanoma has the highest metastatic potential of the primary skin malignancies. Melanoma can occur in any skin type, but is more common in skin types I and II (fair skin). Obtaining a tissue sample for pathologic studies of suspicious skin lesions is critical for diagnosis and planning of appropriate treatment of melanoma. The thickness of the lesion is an important factor in these decisions. Therefore, shave biopsy would be inappropriate for the evaluation of a pigmented lesion. Complete excisional biopsy would be preferable, or, when that is not possible, full-thickness punch biopsy is an acceptable alternative. While sun exposure is an important risk factor for all types of skin cancers, for melanomas there is some evidence that intermittent, intense sun exposure and sunburning is more of a risk than cumulative sun exposure. Actinic keratoses are sun-induced skin lesions that are considered risks for the development of squamous carcinomas. They can be treated with local destructive methods, such as cryosurgery or the topical chemotherapeutic agent 5-fluorouracil. Protection of susceptible skin from excessive sun exposure from childhood is important in reducing the risk of developing skin cancer. Precautions such as wearing broad- brimmed hats, long sleeved clothing, and avoidance of intense midday sunlight are helpful. Using chemical sunscreens with SPF of greater than 15 with frequent reapplication is also beneficial. Even "waterproof" sunscreens need to be reapplied after bathing or swimming.

  Awet cotton T-shirt provides very little, if any, protection from ultraviolet light exposure. Both the UV-A and UV-B rays play roles in skin damage from the sun and it is important to use sun protection products, which block both types of rays. Sun tanning booths are also considered risks for the induction of skin damage and skin cancer as they expose skin to potentially damaging ultraviolet rays.

• Question 398:

  A 5-year-old male is admitted to the hospital following a 3-week history of spiking fevers and fatigue. Your examination reveals pale mucous membranes and skin. You also find splenomegaly.

  You are concerned about a possible malignancy. What is the most common malignancy of childhood?

  A. medulloblastoma
  B. Wilms' tumor
  C. leukemia
  D. neuroblastoma
  E. rhabdomyosarcoma
  C. leukemia

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  Explanation

  The most common malignancy in childhood is leukemia/lymphoma. The most common solid tumors of childhood are CNS tumors, followed by neuroblastoma and Wilms tumors. The mildly elevated WBC with lymphocyte predominance with the presence of "atypical" lymphocytes would indicate that his child most likely has acute EBV infection (infectious mononucleosis). This acute EBV infection is usually subclinical in younger children, but can be manifested by acute hemolytic anemia and splenomegaly.

  Testing for the diagnosis of EBV includes EBV DNA PCR and heterophile antibody response testing (monospot test). Diagnosis usually is made based upon serology testing for anti-EBV IgG and IgM levels. There is no specific therapy indicated for the acute EBV infections. Acute Lyme disease is very uncommon in children. The early stage of acute Lyme disease is characterized by a distinctive rash (erythema migrans). This is then followed by a multiple annular rash of disseminated Lyme disease. Often seen in this stage is cranial nerve palsies, specifically facial nerve (CN VII) palsy. Late Lyme disease is characterized by recurrent arthritis and arthralgia. Serologic testing is only recommended if there is a very high clinical index of suspicion, unlike this child. Acute systemic-onset JRA (Still disease) can present in a child of this age in a nonspecific manner (i.e., fever of unknown origin). Children with Still disease will typically have dramatic elevations in acute- phase reactants (i.e., ESR). This child's ESR being 5 would go against JRA.

• Question 399:

  A 63-year-old Native American male, with a 6-year history of DM, hypertension, and hyperlipidemia, comes to your office as a new patient for a routine examination. He has been experiencing frequent lower back pain and headaches for which he is taking ibuprofen daily for the past 5 weeks. Moreover, he is complaining of mild fatigue. In addition, he is taking aspirin, atorvastatin, verapamil, and glipizide. His physical examination shows a blood pressure of 165/80 and heart rate of 90 bpm. In general, he was not in any distress. His funduscopic examination reveals no signs of diabetic retinopathy. Cardiac examination reveals a regular rate and rhythm with an S4 gallop. His lungs are clear and abdominal examination is unremarkable without any bruit auscultated. He also has 2+ lower extremity pitting edema. Rectal examination reveals brown stool, negative for occult blood. His laboratory results are as follows:

  Which of the following antihypertensive medications would be best implemented in patients with diabetic nephropathy?

  

  A. lisinopril 10 mg orally once daily
  B. clonidine 0.2 mg orally twice daily
  C. metoprolol 25 mg orally twice daily
  D. amlodipine 5 mg orally once daily
  E. hydralazine 25 mg orally three times daily
  A. lisinopril 10 mg orally once daily

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  Explanation

  This patient's presentation and laboratory data are consistent with nephrotic syndrome. Nephrotic syndrome is typically associated with proteinuria of greater than 3.5 g/day, hypoalbuminemia, edema, and hyperlipidemia. Abnormalities commonly seen in nephrotic syndrome include hypocalcemia (due to vitamin D deficiency), low thyroxine levels (due to loss of thyroxine-binding globulin [TBG]), and microcytic, hypochromic anemia (due to transferring loss). Hypocomplementemia may be found in some forms of nephrotic syndrome, but this is not a typical finding. Hematuria is one of the components found in nephritic syndrome.

  This patient has history, physical, and laboratory findings that suggest possible multiple myeloma. For example, his history is pertinent for lower back pain and headaches. Moreover, Bence-Jones protein is not usually detected by urine dipstick but will be detected during a 24-hour urine collection. This would explain why there is relatively little urine protein detected on dipstick but over 5 g on the 24-hour urine. Lastly, multiple myeloma should be considered in an older patient with unexplained anemia. Given these findings, a serum and urine protein electrophoresis would be the best test to order next. A kidney biopsy would usually be diagnostic, but is unnecessary if the electrophoresis is positive. Complement levels and anti- GBM titer would not be of any use at the present time. Checking glycosylated Hgb will inform you of the adequacy of glucose control, but will be of little use with regard to the workup of the nephrotic syndrome. This patient has a low anion gap due to the presence of unmeasured cations in the blood. In this case, they arise from circulating immunoglobulins. The fractional excretion of sodium and urea can be helpful in differentiating prerenal causes from other etiologies of acute renal failure. A split 24-hour urine for protein is helpful in determining the presence of orthostatic proteinuria. Initiation of ACE inhibitors or angiotensin receptor blockers is the best option in patients with diabetic nephropathy, as these medications have been shown to slow the progression of kidney disease. The other medications listed may be used adjunctively, with an ACE inhibitor or angiotensin receptor blocker, if adequate blood pressure control could not be achieved with monotherapy. HIV-associated nephropathy is typically associated with a collapsing glomerulopathy, a variant of focal segmental glomerulosclerosis. Membranous nephropathy is associated with a number of other infections, including syphilis, hepatitis B, and hepatitis C virus. Membranoproliferative glomerulonephritis has also been associated with hepatitis C virus.

• Question 400:

  A 49-year-old male postal worker presents to your office for the evaluation of a lesion on his left arm. The lesion started about a week ago as a red pustule but has grown and now has a thick black scab. The lesion is painless. A coworker showed the patient a similar appearing lesion that she developed on her arm for which her doctor prescribed an oral antibiotic. Examination reveals a 5 cm circular black eschar with some surrounding vesicles. A Gram stain of fluid drained from a vesicle reveals chains of gram-positive bacilli.

  The patient asks how he contracted this infection.

  Which of the following do you tell him?

  A. from direct contact with the coworker who had the similar appearing lesion
  B. ingestion of contaminated food in the postal facility cafeteria
  C. a small skin cut or sore was directly contaminated with spores
  D. inhalation of bacteria from a contaminated ventilation system
  E. exposure to respiratory droplets from an infected person
  C. a small skin cut or sore was directly contaminated with spores

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  Explanation

  B. anthracis causes three diseases in humans: cutaneous, inhalation, and gastrointestinal anthrax. Cutaneous anthrax is the most common of the naturally occurring anthrax diseases. The spores of the gram-positive bacillus can survive for years in soil. The disease cutaneous anthrax occurs when the spores contaminate a wound on the skin of the victim and then start to grow. This disease occurs most commonly in agricultural areas where the soil becomes contaminated by the presence of animals. Initially

  a painless papule develops, followed by vesicles which then ulcerate and a black eschar forms. In the setting of cutaneous anthrax in a postal worker who has a coworker with an apparently similar disease, bioterrorism must be suspected. This type of attack occurred in the Fall of 2001, when anthrax spores were sent through the U.S. Postal system and over 20 persons were infected. In this setting, the most appropriate initial management is to immediately contact the appropriate Public Health Authorities,

  usually the local or state health department. Appropriate treatment will also need to be instituted, under the guidance of the public health specialists, as untreated cutaneous anthrax may carry a 20% mortality rate. Antibiotic therapy would usually be with ciprofloxacin, penicillin, or doxycycline. Anthrax does not spread from person to person, so quarantine is not necessary. Inhalation anthrax is caused by the direct inhalation of spores into the lungs and gastrointestinal anthrax, the least common of the anthrax

  syndromes, is caused by ingestion. Smallpox does not occur naturally anywhere in the world. Therefore, any suspicion of smallpox must be assumed to be a bioterror event and must be reported immediately to public health officials. Physicians should be able to recognize the signs and symptoms of smallpox and be able to distinguish them from the common occurrence of chickenpox. Chickenpox lesions tend to occur in clusters and evolve asynchronously. They are often described as "dew drops on a rose

  petal" as they are vesicles occurring on an erythematous base. The lesions tend to start on the trunk and rapidly spread outward. The rash will be associated with a fever but there are usually few to no prodromal symptoms. Because of the asynchronous growth and outbreaks, a patient will typically have lesions in different stages of evolution. In contrast, smallpox lesions tend to occur synchronously and the lesions tend to be uniform. The rash frequently occurs on the palms and soles. It typically starts on the

  face and arms and then spreads to the trunk and legs. The development of the rash tends to be slower than that of chickenpox. There is often a dramatic prodrome of high fever, malaise, headache, and backache for 24 days prior to the onset of the rash. Smallpox carries an approximately 30% mortality, while mortality associated with chickenpox is very low.