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USMLE I TEST BLOCK VII

A 38-year-old man is brought to his doctor by his wife, who describes a distinct change in his personality over the past several weeks. Although he holds a successful job, he has not gone to work for the past week because he “doesn’t feel like it.” He typically sits in bed and stares blankly at the television for hours at a time. Occasionally she finds him crying for no apparent reason. He enters the examination room very slowly and refuses to make eye contact with the physician. He has lost nearly 6.8 kg (15 lb) in 1 year. When directly questioned about suicidal ideation, he indicates that he often thinks about dying and has thought about jumping out the window of his office on the 27th floor. He also states that he has never experienced anything like this before in his life. Which of the following is most appropriate for this patient?

Explanation The correct answer is C. This man is suffering from a major depressive episode, characterized by weight loss, anhedonia, tearfulness, and psychomotor retardation. Feelings of inadequacy and excessive guilt pervade his thoughts. Antidepressant medication is indicated. In addition, his extensive suicidal ideation put him at increased for suicide. Citalopram is a selective serotonin reuptake inhibitor; these drugs have minimal adverse effects in comparison to other antidepressants, such as tricyclic antidepressants and monoamine oxidase inhibitors, both of which can be lethal in overdose or with certain foods or other medications. Other examples of commonly used selective serotonin reuptake inhibitors include fluoxetine, sertraline, and escitalopram

USMLE I TEST BLOCK VII

A 58-year-old man presents to the emergency department with 1 day of high fever to 39.5°C (103.1°C) along with muscle aches and malaise. During the initial interview, he remembers his name but is not oriented to place or time, and he cannot recall the names of his four children. He has no known medical problems. His wife claims that he is in “perfect health” and reports that he was out playing in the yard with their grandchildren 3 days ago. They have not been out of the country in >2 years and have no animals at home. A peripheral blood smear demonstrates morulae within several monocytes. Laboratory studies show: Platelet count: 84,000/mm³ WBC count: 2500/mm³ Hemoglobin: 14.2 g/dL Serum transaminases: Mildly elevated Which of the following is most likely to have caused this patient’s disease?

ExplanationThe correct answer is C. Ehrlichia chaffeensisis an intracellular bacteria that causes human monocytic ehrlichiosis, carried by the Ixodes tick. The disease can present with fever, in addition to nonspecific symptoms such as malaise, myalgias, headache, and chills, in addition to nausea and vomiting. Mental status changes, such as the confusion exhibited by this patient, are common. Laboratory abnormalities include leukopenia, thrombocytopenia, and mildly elevated transaminases. Examination of the buffy coat of a peripheral blood smear can sometimes demonstrate morulae in leukocytes but is rarely seen. Diagnosis can definitively be made on serologies; detection of a four-fold increase in E. chaffeensis antibody titer (to at least 1:64) by indirect immunofluorescence in paired serum samples obtained approximately 3 weeks apart are sufficient for diagnosis. Treatment is with doxycycline.

USMLE I TEST BLOCK VII

A 20-year-old recent immigrant presents to his primary care physician with complaints of jaundice, discoloration of his eyes, tremor, dysphagia, and depressed mood. Examination reveals jaundice, green-brown deposits in the cornea, hepatomegaly, tremor, and rigidity of the extremities. The physician suspects the patient suffers from a specific liver metabolic abnormality and wants to confirm his diagnosis with further evaluation. Which of the following would be the most appropriate next step in diagnosis?

ExplanationThe correct answer is B. Decreased ceruloplasmin, along with Kayser-Fleischer rings and neurologic abnormalities, is characteristic of Wilson’s disease. Patients may also present with jaundice, hematemesis, depression, dysphagia, speech impairment, and abdominal distention with hepatomegaly and/or splenomegaly.

USMLE I TEST BLOCK VII

A 6-year-old boy presents to the clinic with dyspnea at rest and cough productive of thick mucoid sputum over the last 5 days. He has a temperature of 39.4°C (103°F), which is only temporarily relieved by acetaminophen. He has had two episodes of pneumonia in the last 5 months, and a maternal uncle who died at an early age. On examination he is a thin child who is breathing rapidly. Auscultation of the chest shows decreased breath sounds in both bases. X-ray of the chest shows consolidation of the left and right lower lobes. Since the patient cannot produce a good sputum sample, bronchoscopy is performed and a lavage sample is sent. Preliminary Gram stain results are as follows: Color: Yellow Consistency: Thick Neutrophils: Many Gram stain: Numerous gram-negative rods. Which of the following causative organisms is most likely involved?

ExplanationThe correct answer is C. In any child presenting with recurrent pneumonia and poor growth, cystic fibrosis should be considered. Since the pathophysiology results in decreased bacterial clearance from the lungs secondary to impaired ciliary function, these patients are susceptible to a range of pulmonary infections including Staphylococcus aureus, Burkholderia cepacia, Stenotrophomonas maltophilia, and Haemophilus influenzae. However, Pseudomonas infection in patients with typical histories for cystic fibrosis virtually assures the diagnosis in the absence of confirmatory sweat chloride or genetic testing

USMLE I TEST BLOCK VII

A delirious 82-year-old man with terminal pancreatic cancer is having episodes of hypotension due to a systemic infection. The intensive care unit team is considering use of potent intravenous antibiotics to treat the infection. Treatment is begun, despite a signed living will in the form of a “Do Not Resuscitate” (DNR) order. Did the team make the wrong management decision?

ExplanationThe correct answer is A. Although this patient suffers from a terminal condition and has indicated through his DNR order that resuscitation should not be performed if he suffers from cardiac or respiratory arrest, the advance directive does not apply to action against treatable conditions. A living will in the form of a DNR order is an advance directive provided by he patient that indicates the desire to prevent life-sustaining treatment in the event of a terminal disease or a persistent vegetative state. However, feeding, intravenous fluids, treatment of infections or other treatable conditions, and pain management are not restricted under a DNR order.

USMLE I TEST BLOCK VII

A 58-year-old long-time alcoholic is brought to the emergency department after vomiting blood. After a comprehensive work-up, the bleeding is determined to be due to ruptured esophageal varices. The patient has been treated for this condition several times before. He is admitted and a management plan is determined. Four days following a new intervention, the patient becomes confused, agitated, and lethargic. On examination he demonstrates asterixis and hyperreflexia. Given the onset of symptoms following treatment, what was the most likely new intervention

Explanation The correct answer is B. The treatment algorithm for variceal hemorrhage includes somatostatin therapy or an analog and endoscopic therapy, including band ligation and sclerotherapy. If this is unsuccessful or bleeding recurs continually, then balloon tamponade or portal systemic shunt placement should be considered. Although portal systemic shunt placement is an excellent means to decompress the portal circulation, the main negative consequence is due to the diversion of blood away from the hepatic filtering mechanism. In other words, toxin-filled blood circumvents the liver and goes directly to the systemic circulation, thus putting the patient at risk for hepatic encephalopathy. This patient, a recurrent bleeder, likely underwent shunt placement and is now suffering from encephalopathy

USMLE I TEST BLOCK VII

A 5-year-old boy presents with fever, pallor, and bony pain and is diagnosed with acute lymphoid leukemia following extensive laboratory work-up and bone marrow biopsy. His laboratory studies revealed a WBC count of 240,000/mm³, hemoglobin of 8.1 g/dL, and platelet count of 79,000/mm³. Treatment with chemotherapy is initiated emergently. Twelve hours after his therapy is begun he develops acute ventricular arrhythmias. Review of his bedside chart reveals anuria over the past 8 hours, despite vigorous provision of intravenous fluids. Laboratory evaluation reveals a blood urea nitrogen level of 150 mg/dL, sodium of 2.5 mEq/L, and potassium of 8.9 mEq/L. Urinalysis reveals uric acid crystals in his urine. Which element of his disease and/or therapy is most likely to be accountable for his condition?

ExplanationThe correct answer is C. This patient is experiencing acute tumor lysis syndrome. This situation occurs when large numbers of rapidly proliferating cells (as are present in acute lymphoid leukemia) are exposed to chemotherapeutic agents. Cellular destruction results in release of intracellular contents into the bloodstream, leading to hyperuricemia and hyperkalemia. Uric acid precipitates in the renal tubules, causing oliguric/anuric acute renal failure, and cardiac arrhythmias may occur due to high potassium levels. This syndrome is largely preventable with administration of allopurinol, aggressive hydration, and close monitoring of electrolytes; however, patients with acute lymphoid leukemia who have very high WBC values at diagnosis, as well as patients with Burkitt’s lymphoma, remain at risk.

USMLE I TEST BLOCK VII

A 48-year-old man presents to the emergency department complaining of stabbing abdominal pain that increases when he tries to eat. He admits to current cocaine and alcohol use. He is hypertensive to 162/100 mm Hg and diaphoretic. His amylase and lipase levels confirm that he has acute pancreatitis. He is placed on empiric antibiotics, aggressive intravenous fluids, and is made “nothing by mouth” status. His blood pressure remains elevated. What agent should the physician use to lower his blood pressure?

ExplanationThe correct answer is C. Given this patient’s history, his persistent hypertension is likely to be a withdrawal symptom. Although not ordinarily used as antihypertensives, benzodiazepines are indicated in the supportive treatment of cocaine/amphetamine and alcohol withdrawal, and will treat the underlying cause of this patient’s hypertension. In this instance, an ECG should also be ordered to rule out ischemic injury secondary to cocaine use, which may be masked by the abdominal pain.

USMLE I TEST BLOCK VII

A 28-year-old woman presents to the emergency department complaining of sharp abdominal pain localized to the left lower quadrant. She reports feeling perfectly well until half an hour prior to her arrival. When asked if she could be pregnant, the patient responds that her last menstrual period was 2 weeks ago, and that she has not been sexually active during the past month. The patient’s temperature is 36.9°C (98.4°F) and blood pressure is 110/70 mm Hg. Abdominal examination elicits guarding and rebound tenderness. Pelvic examination is normal, and urine β-human chorionic gonadotropin is negative. Which of the following is the most likely cause of this patient’s abdominal pain?

ExplanationThe correct answer is A. The sudden onset of this patient’s abdominal pain, the presence of guarding and rebound tenderness, and the fact this patient’s last menstrual cycle was 2 weeks ago, all suggest the possibility of a ruptured corpus luteum cyst. Normally, a mature follicle transforms into a corpus luteum after ovulation, only to atrophy into a corpus albicans around the time of the next ovulation. Occasionally, a corpus luteum will fail to degenerate and result in the formation of a cyst; when these rupture, the patient experiences acute abdominal pain. It can be difficult to distinguish clinically between this pathology and adnexal torsion, perforated bowel, or ectopic pregnancy

USMLE I TEST BLOCK VII

A 25-year-old African-American woman develops a nonproductive cough and dyspnea on exertion that progressively worsens over several months. X-ray of the chest demonstrates bilateral hilar adenopathy with interstitial infiltrates bilaterally. Biopsy of a waxy nodule on the woman’s arm reveals noncaseating granuloma formation. Which of the following symptoms is most likely to be seen in patients with this disease?

ExplanationThe correct answer is B. This patient has a pelvic fracture with resultant hemodynamic in stability. In such a patient, one must never explore a suspected pelvic or retroperitoneal hematoma. Rather, follow the patient with serial hematocrit and hemoglobin measurements to monitor for sufficient intravenous resuscitation. This patient should not be subjected to major pelvic surgery at this point because these hematomas often are a collection of blood from many vessels, most of which are not amenable to direct surgical control. The best chance to curb the patient’s bleeding is external fixation.

USMLE I TEST BLOCK VII

A 56-year-old man with diabetes and hypertension presents to the ophthalmology clinic with a history of a blind spot in his right eye. He reports that it is painless, occurred suddenly, and is only in his right eye. He has a visual field loss in the right superior hemifield. Examination of the retina shows peripheral hemorrhages and disc congestion. Which of the following is the most likely diagnosis?

Explanation The correct answer is B. The differential diagnosis of painless unilateral vision loss can include several possibilities such as central and peripheral vein occlusion, diabetic retinopathy, and hypertensive retinopathy. The patient reports a history of hypertension and diabetes, both of which are risk factors for branch retinal vein occlusion. Additionally, funduscopic examination shows superficial hemorrhages in a sector of the retinal along a retinal vein. The hemorrhages usually do not cross the horizontal raphe (midline)

USMLE I TEST BLOCK VII

The parents of a 4-week-old white boy bring their son to the pediatric emergency department concerned about their son’s feeding patterns. His mother reports he was feeding well for the first several days but developed nonbilious emesis toward the end of his second week of life. The episodes of emesis have worsened and now occur after every feeding, with some episodes being projectile in nature. Immediately after vomiting, the newborn is hungry and ready to feed again. He has a small, mobile nontender epigastric mass on physical examination. Heart rate is 128/min, blood pressure is 80/52 mm Hg, respiratory rate is 37/min, and temperature is 37.5°C (99.5°F). What acid base disorder is the patient most at risk of developing?

ExplanationThe correct answer is A. The patient has pyloric stenosis. Pyloric stenosis has a multifaceted etiology, including genetic and environmental factors. It is more common in boys (4–6:1) and firstborn children. Nonbilious, nonbloody, projectile vomiting after feeding develops 3–6 weeks after birth. Infants with pyloric stenosis are often described as “hungry vomiters,” given their desire to feed immediately after episodes of emesis. As a result of the malnourishment and dehydration, infants with pyloric stenosis develop hypochloremic, hypokalemic, metabolic alkalosis. This metabolic acid-base disorder is caused by the massiveloss of gastric hydrochloric acid. As the patient enters a state of volume depletion and loses hydrochloric acid, the kidney responds to the metabolic alkalosis by excreting bicarbonate in the urine. This results in obligate potassium and sodium loss. Hypochloremia also induces the renin-angiotensin aldosterone axis, which induces increased aldosterone production and maintains the hypokalemic alkalosis. In addition, the alkalotic state induces hydrogen ions to move out of the intracellular space, where they are replaced by potassium ions moving into the cells, furthering hypokalemia.

USMLE I TEST BLOCK VII

A 51-year-old woman presents to her primary care physician complaining of headache for the past 2 weeks. Further questioning reveals weakness over the past several months that has led to gradual impairment of physical activities. The patient has no other complaints, takes no medications other than a multivitamin, and smokes one pack of cigarettes a day. Her blood pressure is 150/94 mm Hg. Laboratory studies reveal a potassium level of 3.1 mEq/L and sodium of 143 mEq/L. Imaging reveals bilateral adrenal hyperplasia. Which of the following would be most appropriate for this patient?

ExplanationThe correct answer is D. The patient is suffering from primary hyperaldosteronism, and from the effects of elevated aldosterone: hypertension, hypokalemia, and metabolic alkalosis. Symptoms could be alleviated by reversing or blocking the effects of aldosterone. Aldosterone increases sodium reabsorption and increases potassium secretion and hydrogen ion secretion. Spironolactone antagonizes aldosterone at its receptor in the distal convoluted tubule and would be likely be beneficial in this patient

USMLE I TEST BLOCK VI

An otherwise healthy 9-year-old girl is brought to the emergency department after the acute development of fever (38.8°C [101.8°F]), nausea, vomiting, diarrhea, and crampy periumbilical abdominal pain. A review of her diet in the past 48 hours includes cereals, fruits, egg salad sandwiches, steamed vegetables, hamburger, grilled chicken, Christmas cookies, and homemade eggnog. At the time of evaluation, her vital signs are stable but she has a mild fever of 38.4°C (101.1°F). She is fatigued but alert. Her abdominal examination is notable for periumbilical tenderness, but no guarding or rebound tenderness is noted, and no masses are palpated. Select the most likely etiologic agent.

ExplanationThe correct answer is B. Acute enteritis is the most common manifestation of enteric salmonellosis. Patients infected with nontyphoidal Salmonella experience an acute onset of nausea, vomiting, and abdominal cramping, followed by mild to severe watery diarrhea that may contain blood and mucus. The incubation period for infection is typically 6–72 hours with a mean incubation period of 24 hours. The major source of nontyphoidal Salmonella is constituted by animals, specifically poultry and poultry products. In this case, the patient’s clinical presentation is consistent with salmonellosis, and the recent inclusion of egg salad, chicken, and homemade eggnog in her diet should lead to high suspicion of the diagnosis. Therapy is aggressive hydration alone; in fact, antibiotics are detrimental in this situation and should never be prescribed.

USMLE I TEST BLOCK VI

The parents of an otherwise healthy 13-monthold boy present to the emergency department in the winter concerned about their son’s recent diarrhea and vomiting. They report that he developed a mild fever approximately 2 days ago along with nonbloody, nonbilious vomiting. They took him to the pediatrician at that time, and he was diagnosed with gastroenteritis. His parents were told to monitor his fluids closely and return if his condition changed. He has now stopped vomiting but has developed watery stools that are passed approximately every 1–2 hours. His parents report that he attends day care, and recently there have been numerous children out of the program because of similar illness. His heart rate is 122/min, blood pressure is 80/50 mm Hg, and respiratory rate is 28/min. His physical examination is notable for dry mucous membranes. Select the most likely etiologic agent.

ExplanationThe correct answer is A. Rotavirus is the most important cause of severe dehydrating diarrhea in early childhood. It is most commonly encountered during the winter months and is spread easily along the fecal-oral route. Child care centers and children’s hospitals are common sites of encounter with the infectious agents. The virions of the rotaviruses are highly contagious and shed in high concentrations in the stool before and during the clinical manifestations. Patients typically present after an incubation period of <48 hours with low-grade to moderate-grade fever and simultaneous vomiting. Watery diarrhea is a later manifestation, often occurring for 5–7 days. Patients must be monitored closely for deteriorating clinical condition secondary to dehydration, which if left untreated can lead to eventual death. Treatment is aggressive hydration and antibiotic therapy is not recommended.

USMLE I TEST BLOCK VI

A 22-year-old G2P1 woman at 38 weeks’ gestation presents to the labor and delivery suite in labor after a pregnancy with poor prenatal care. After several hours of labor, her temperature is 39.1°C (102.4°) and she has significant abdominal tenderness. Her WBC count is 18,400/mm³. The child is delivered with Apgar scores of 8 at 1 and 5 minutes, but is lethargic the day after delivery, with a temperature of 34.8°C (94.6°F), respiratory rate of 24/min, heart rate of 186/min, and mean blood pressure of 32 mm Hg. Which of the following is the most likely cause of this neonate’s condition?

ExplanationThe correct answer is C. Because the parathyroid hormone level and serum calcium concentration is high, the patient most likely has primary hyperparathyroidism. Single adenoma is the most frequent cause of primary hyperparathyroidism, accounting for 80% of cases.

USMLE I TEST BLOCK VI

Explanation The correct answer is B. Group B streptococci (GBS) commonly colonize the gastrointestinal or genital tracts of adults. In pregnant females, colonization with GBS can lead to chorioamnionitis and sepsis. In newborn infants, group B streptococcal infection can lead to bacteremia, sepsis, and meningitis. Screening for GBS colonization is commonly done in pregnant women between 35–37 weeks’ gestation. Women who are GBS positive then receive IV penicillin in labor to protect the infant from getting the infection during delivery

USMLE I TEST BLOCK VI

A 72-year-old woman undergoes three-vessel coronary artery bypass graft for coronary artery disease. Her postoperative course is complicated by wound infection leading to sepsis with multidrug-resistant Klebsiella. Her sepsis is difficult to manage, and she is on pressors, fluids, and antibiotics for several days before becoming afebrile and hemodynamically stable. Her creatinine rises postoperatively, and on postoperative day 4 electrolytes show blood urea nitrogen (BUN) of 34 mg/dL and creatinine of 2.6 mg/dL. Urine sodium level is 46 mEq/L, fractional excretion of sodium is calculated as 2.1%, and urine osmolarity is 310 mOsm. Urinalysis shows muddy brown granular casts. Over the next week her creatinine level continues to rise despite aggressive fluid management. However, she continues to make small amounts of urine, and BUN and creatinine levels gradually return to normal over the next few weeks. Which of the following is the most likely pathogenesis of this woman’s acute renal failure?

Explanation The correct answer is D. This woman most likely has acute tubular necrosis (ATN), which presents with a picture of acute renal failure, often following sepsis, hypotension, or other ischemic insult. Although prerenal failure can also result from these, it resolves more rapidly with fluid administration, and presents with a prerenal picture, including BUN:creatinine ratio >20:1 and fractional sodium excretion <1%. ATN, in contrast, lasts longer, with creatinine elevation often persisting for several weeks, and presents with signs of renal failure such as elevated BUN and creatinine, fractional sodium excretion >2%, and low urine osmolarity due to impaired urine concentrating ability despite hypovolemia. Muddy brown casts on urinalysis are characteristic of ATN

USMLE I TEST BLOCK VI

A 37-year-old man presents to his new primary care physician with a small, symmetric, monochromatic brown macule with regular borders that has been on his forearm “for many years.” After complaining that “none of my doctors have taken me seriously,” he states that he believes he is dying of melanoma. He adds that he has seen several specialists over the past year, and while all of them have assured him that his lesion is “just a mole,” he is certain that this is not the case. The patient has no other complaints, no systemic symptoms, and no medical or surgical history. Which of the following is the most likely diagnosis?

ExplanationThe correct answer is C. This patient is exhibiting the symptoms of hypochondriasis, which involves the persistent fear and conviction that one is very ill, combined with the misinterpretation of normal bodily symptoms. The DSM-IV-TR criteria for hypochondriasis require that the patient have at least a 6-month history of persistent and debilitating fear that is not diminished by appropriate medical evaluation and reassurance. Men and woman are equally affected, and the disorder usually presents in middle age. Treatment consists of reassurance and a referral for psychotherapy

USMLE I TEST BLOCK VI

A 56-year-old woman is brought to the emergency department by her spouse for evaluation of obtundation. Earlier in the evening, the spouse says the patient complained of shakiness and a racing heartbeat. The patient has type 2 diabetes mellitus and recently started sulfonylurea therapy. The patient also began taking 81 mg of aspirin at the time of her diabetes diagnosis. There is a family history of heart disease. On examination the patient is oriented to person only, appears lethargic, and is diaphoretic. Her temperature is 36.9°C (98.4°F), blood pressure is 155/91 mm Hg, pulse is 112/min, and respiratory rate is 18/min. Laboratory studies are pending. Which of the following is most likely to be used in the management of this patient?

ExplanationThe correct answer is D. The patient is hypoglycemic, and normalization of the blood glucose level is likely to alleviate her symptoms. Sulfonylureas act primarily as insulin secretagogues, but also limit hepatic glucose production, decrease lipolysis, and decrease hepatic clearance of serum insulin. When initiating these medications, it is important to use the lowest possible dose and to increase slowly to avoid overshoot hypoglycemia.

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reigan 5 days ago

hello! i’m currently studying anatomy and phys, and i’ve been wondering if there’s a difference between the terms medial/lateral & central/peripheral. are they interchangeable?

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So I’m currently in Highschool and I want to pursue a degree in psychiatry. How can I go about preparing for it now?

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Anyone has any idea how should we treat small single purple_brown spot on gum with yet unknown cause and symptoms