1. A 65-year-old male presents with jaundice for 2–3 weeks, fatigue and increasing epigastric pain. He has no history of peptic ulcers and says the pain does not relate to eating in anyway. His epigastric pain is midline and he has had some recent back pain. His urinary bilirubinogen and serum bilirubin are elevated (serum bilirubin 5.8 mg/dl). Helical CT reveals a suspicious mass in the head of the pancreas adjacent to the descending duodenum. The gallbladder is significantly enlarged. Which of the following is the likely cause of the elevated bilirubin?

A. Viral hepatitis

B. Blocked cystic duct

C. Open hepatic duct

D. Blocked duodenal papilla

E. Gilbert syndrome

The answer is D.

EXPLANATION: The likely cause of the elevated bilirubin is a blocked pancreatic and bile duct at the duodenal papilla. Pancreatic cancer (usually ductal adenocarcinoma) frequently arises from the head of the pancreas where it blocks the normal flow of bile out of the liver, via the hepatic duct and gallbladder, via the cystic duct which join to form the (common) bile duct that passes through the substance of the head of the pancreas where it joins the main pancreatic duct just before forming the hepatopancreatic ampulla at the second portion of the duodenum. As a consequence of the blockage [not open hepatic duct (answer c)] of the normal exit of bile from the body bilirubin levels increase and jaundice (yellowing) develops. Blockage of the cystic duct (answer b) may just lead to a gallbladder enlargement/inflammation. Viral hepatitis (answer a) would normally not be associated with pancreatic cancer. Gilbert syndrome (answer e) is due to mild, chronic unconjugated hyperbilirubinemia and is not involved.

2. A 39-year-old man presents with severe writhing back pain, hematuria, and nausea. An intravenous pyelogram (IVP) confirms a diagnosis of renal calculi. The presence of strongly opaque stones on the plain film is suggestive of calcium oxalate stones, which have an increased incidence with hypophosphatemia. The renal clearance of phosphate is increased by which of the following hormones?

A. Aldosterone.

B. Parathyroid hormone

C. Norepinephrine

D. Vasopressin

E. Angiotensin

The answer is B.

EXPLANATION: Between 85 and 90% of the filtered phosphate is reabsorbed in the proximal tubule by a sodium-dependent secondary active transport system. The transporter is electrically neutral, requiring two Na⁺ molecules for every HPO₄^2– molecule that it transports. The transporter is inhibited by parathyroid hormone (PTH). The decreased reabsorption of phosphate results in an increased clearance from the plasma. PTH is released from the parathyroid gland in response to lowered plasma Ca²⁺ concentrations. In addition to inhibiting the reabsorption of phosphate from the proximal tubule, PTH increases the reabsorption of Ca²⁺ from the loop of Henle.

3. An 18-year-old woman presents with abdominal pain localized to the right lower quadrant, nausea and vomiting, mild fever, and an elevation of the peripheral leukocyte count to 17,000/L. An appendectomy is performed. Which of the following statements best describes the expected microscopic appearance of her appendix?

A. An appendix with a normal appearance.

B. Neutrophils within the muscular wall

C. Lymphoid hyperplasia and multinucleated giant cells within the muscular wall

D. A dilated lumen filled with mucus

E. A yellow tumor nodule at the tip of the appendix

The answer is B.

EXPLANATION: Acute appendicitis, a disease found predominantly in adolescents and young adults, is characterized histologically by acute inflammatory cells (neutrophils) within the mucosa and muscular wall. Clinically, acute appendicitis causes right lower quadrant pain, nausea, vomiting, a mild fever, and a leukocytosis in the peripheral blood. These symptoms may not occur in the very young or the elderly. The inflamed appendiceal wall may become gangrenous and perforate in 24 to 48 h. Even with classic symptoms, the appendix may be histologically unremarkable in up to 20% of the cases. False-positive diagnoses are to be preferred to the possible severe or fatal complications of a false-negative diagnosis of acute appendicitis that results in rupture. Lymphoid hyperplasia with multinucleated giant cells (Warthin-Finkeldey giant cells) is characteristic of measles (rubeola). These changes can be found in the appendix, but this is quite rare. Dilation of the lumen of the appendix, called a mucocele, may be caused by mucosal hyperplasia, a benign cystadenoma, or a malignant mucinous cystadenocarcinoma. If the latter tumor ruptures, it may seed the entire peritoneal cavity, causing the condition called pseudomyxoma peritonei. The most common tumor of the appendix is the carcinoid tumor. Grossly it is yellow in color and is typically located at the tip of the appendix. Histologically, carcinoids are composed of nests or islands of monotonous cells. Appendiceal carcinoids rarely metastasize.

4. A 37-year-old woman is brought into the ED by her friend who states that the patient swallowed approximately 50 capsules of 325-mg acetaminophen 6 hours ago in an attempted suicide. The patient states she feels nauseated and vomits while you take her history. Her BP is 100/75 mm Hg, HR is 97 beats per minute, temperature is 98.9°F, RR is 18 breaths per minute, and oxygen saturation is 99% on room air. Examination is unremarkable except for mild epigastric tenderness. Which of the following is the correct antidote for APAP overdose?

A. NAC

B. Physostigmine

C. Flumazenil

D. Naloxone

E. Digibind

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The answer is A.

EXPLANATION: NAC is the cornerstone of therapy for the potentially lethal acetaminophen overdose. NAC acts as a glutathione precursor to reduce NAPQI (N-acetyl-p-benzoquinoneimine), the toxic metabolite of acetaminophen. It can be administered orally or intravenously. NAC is most effective if administered within 8 hours of the ingestion; however, it may still be of benefit if given more than 24 hours after an acute acetaminophen overdose.

(b) Physostigmine is used for an anticholinergic overdose. (c) Flumazenil is a benzodiazepine antagonist used occasionally in a benzodiazepine overdose. Its use can precipitate benzodiazepine withdrawal and seizures in chronic benzodiazepine users. (d) Naloxone is a -receptor antagonist and is used in opioid overdoses. (e) Digibind is the antidote for digitalis glycoside poisoning.

5. A 17-year-old male is brought to the emergency room with confusion and incoordination. He is uncooperative and refuses to provide further history. Physical examination reveals an RR of 30; the vital signs are otherwise normal as is the general physical examination. Laboratory values are as follows:

Na: 135 - K: 2.7 - HCO₃: 15 - Cl: 110

Arterial blood gases: PO₂ 92, PCO₂ 30, pH 7.28 –

Urine: pH 7.5, glucose: negative  - Ca: 9.7 mg/dL - PO₄: 4.0 mg/dL

Which of the following is the most likely cause of the acid base disorder?

A. GI loss owing to diarrhea

B. Proximal renal tubular acidosis

C. Disorder of the renin-angiotensin system

D. Distal renal tubular acidosis

E. Respiratory acidosis

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The answer is D.

EXPLANATION: The patient has a metabolic acidosis. Respiratory compensation is appropriate, and the anion gap is normal. Therefore, he has a hyperchloremic (normal anion gap) metabolic acidosis. Common causes include renal tubular acidosis, bicarbonate loss owing to diarrhea, and mineralocorticoid deficiency.

In a metabolic acidosis, the urine pH should be low (ie, the patient should be trying to excrete the excess acid). This patient's high urine pH is therefore diagnostic of renal tubular acidosis (RTA). Proximal RTA is associated with glycosuria, phosphaturia, and aminoaciduria (Fanconi syndrome). Since the serum phosphorus is normal and glycosuria is absent, proximal RTA is unlikely. GI Loss of bicarbonate caused by diarrhea would be associated with an appropriately acidic urine (pH less than 5.5). Disorders of the renin-angiotensin-aldosterone system are associated with hyperkalemia, not hypokalemia. The low PCO₂ excludes respiratory acidosis. So, this patient has a distal RTA, probably because of toluene inhalation (glue sniffing). Toluene can lead to life-threatening metabolic acidosis and hypokalemia.

6. A 73-year-old man has had 3 episodes of visual loss in the right eye. The episodes last 20 to 30 minutes and resolve completely. He describes the sensation as like a window shade being pulled down in front of the eye. He has a history of hypertension and tobacco use. He denies dyspnea, chest pain, palpitations, or unilateral weakness or numbness. On examination the patient appears healthy; his vital signs are normal and the neurological examination is unremarkable. An ECG shows normal sinus rhythm without evidence of ischemia or hypertrophy. Initial laboratory studies are normal. Both noncontrast CT scan of the head and MR scan of the brain are normal. What is the best next step in this patient's management?

A. Begin anticoagulation with low-molecular-weight heparin and warfarin.

B. Obtain an echocardiogram.

C. Check for antiphospholipid antibodies and homocysteine levels.

D. Order a carotid duplex ultrasonogram and begin antiplatelet therapy.

E. Begin lamotrigine for probable nonconvulsive seizure.

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The answer is D.

EXPLANATION: This patient has suffered several transient ischemia attacks with the classic description of amaurosis fugax. Although the traditional symptom duration of less than 24 hours is often cited, most TIAs last less than 1 hour, usually 15 or 20 minutes. Many patients whose symptoms last for several hours are found to have ischemic strokes on MRI imaging. TIAs carry a high risk of neurological morbidity and should be promptly evaluated and treated. Five percent of patients will have a full-blown stroke within the next 2 weeks.

Assessing the extracranial carotid arteries for evidence of atherosclerosis is crucial in patients with anterior circulation TIAs. If a common or internal carotid stenosis of 70% or greater is found, carotid endarterectomy has been proven to decrease the risk of subsequent stroke. Lesions of the external carotid artery do not cause CNS symptoms. Cardiogenic sources of clots (ie, atrial fibrillation, mitral valve disease, intracardiac tumors) usually cause large vessel ischemic strokes rather than TIAs; so echocardiography would be less important in this patient. The use of anticoagulants in acute stroke has diminished greatly and is primarily used in cases of demonstrated cardiogenic emboli. For the typical atherosclerotic process, antiplatelet therapy is preferred. Testing for thrombophilia is rarely helpful in patients with TIA. These tests may be helpful in patients with large vessel strokes and no identifiable source of the stroke. Amaurosis fugax would not be a manifestation of seizure disorder.

7. A patient has been in the coronary care unit for the past 24 hours with an acute anterior myocardial infarction. He develops the abnormal rhythm shown below, although blood pressure remains stable at 110/68. Which of the following is the best next step in therapy?

A. Perform cardioversion.

B. Arrange for pacemaker placement.

C. Give digoxin.

D. Give propranolol.

E. Give lidocaine.

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The answer is B.

EXPLANATION: The ECG shows complete heart block. Although at first glance the P waves and QRS complexes may appear related, on closer inspection they are completely independent of each other (ie, dissociated). Complete heart block in the setting of acute myocardial infarction requires temporary (and often permanent) transvenous pacemaker placement. Atropine may be used as a temporizing measure. You would certainly want to avoid digoxin, beta-blockers, or any other medication that promotes bradycardia. There is no indication on this strip for cardioversion such as for atrial fibrillation/flutter or ventricular tachycardia/fibrillation. Lidocaine is contraindicated because it might suppress the ventricular pacemaker, leading to asystole

8. You are evaluating a 21-year-old woman with an erythematous, tender, and edematous hand. She reports that while playing with her cat 3 days ago, he bit her and punctured the skin. The area around the bite is inflamed, and there is a purulent discharge from the puncture site. Which of the following is the most likely infecting organism?

A. Clostridium perfringens

B. Staphylococcus aureus

C. Streptococcus pyogenes

D. Pasteurella multocida

E. Haemophilus influenzae

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The answer is D.

EXPLANATION: Hand cellulitis often follows puncture wounds, and cat bites may often produce infection with P multocida. Most skin infections are due to S aureus or S pyogenes. Clostridium perfringens may produce gas, and should be considered as a cause for cellulitis that can lead to gangrene, especially if crepitus is found on clinical examination. Haemophilus influenzae sometimes infects the skin of younger children.

9. An 82-year-old woman complains of worsening headaches and episodes of transient visual loss and diplopia. When she chews, her jaw muscles ache until she stops chewing. Examination reveals a tender nodular right temporal artery. She has a mild normocytic anemia; sedimentation rate is 95. What is the appropriate diagnosis?

A. Tension headache

B. Cluster headache

C. Migraine headache

D. Temporal arteritis

E. Brain tumor

F. Sinusitis

G. Temporomandibular joint dysfunction

H. Tic douloureux

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The answer is D.

EXPLANATION: Tension headaches are the leading cause of chronic headaches, and 90% are bilateral. These headaches are described as dull, constricting, and bandlike. Associated muscular tenderness may be present.

Temporal arteritis may cause scalp tenderness localized to the involved vessel. It is primarily a disease of the elderly Blindness caused by occlusion of the ophthalmic artery is the feared complication. Temporal artery biopsy is often needed to confirm the diagnosis, since treatment with oral steroids is fraught with complications in this age group.

10. A 30-year-old male is brought to the emergency room from prison, where he works in the paint shop. He is barely arousable but has no focal abnormalities. He has no past medical history. CT scan of the head is normal. Urine toxicology screen is negative. Ethanol and acetaminophen are not detectable. Laboratory data is as follows:

Na: 140 mEq/L- K: 5.1 mEq/L - Cl: 100 mEq/L - HCO_3:10 mEq/L- Creatinine 1.2 mg/dL

Blood ethanol: nondetectable - Blood glucose: 110 mg/dL

Arterial blood gases: PO₂ 88, PCO₂ 23, pH 7.21

Which of the following tests will provide the key to correct diagnosis?

A. Serum ketones

B. Serum lactate

C. Serum creatine kinase

D. Measured plasma osmolality

E. Magnetic resonance scan of the head

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The answer is D

EXPLANATION: This patient appears intoxicated and has a severe anion gap acidosis (AG=30 mEq/L). This scenario suggests toxic alcohol ingestion, and the osmolar gap should be calculated. The estimated plasma osmolality is calculated as follows: 2xNa+BUN/2.8+glucose/18+blood ethanol/4.6 (denominators are a function of molecular weight of each substance). Here the calculated osmolality is 288 mOsm/L (2x138+14/2.8+90/18+0/4.6). This patient is found to have a measured plasma osmolality of 320 mOsm/L. The measured osmolality of 320 mOsm/L minus the calculated osmolality of 288 mOsm/L gives an osmolar gap of 32 (normal less than 10) due either to methanol or ethylene glycol. In this case, methanol, used in paint thinners, is likely. Ethylene glycol, used in antifreeze, is frequently associated with hypocalcemia, renal failure, and crystalluria. Serum ketones should be checked, but diabetic ketoacidosis is unlikely with a blood sugar of 110 mg/dL, and alcoholic ketoacidosis rarely, if ever, causes acidosis of this severity. Serum lactate should be checked, but in an afebrile patient with normal blood pressure, lactic acidosis is unlikely to be the primary cause. Rhabdomyolysis does not cause a wide anion gap metabolic acidosis; so a CK level would not be helpful. A primary CNS event would not account for this patient's wide anion gap metabolic acidosis.

11. A 55-year-old obese woman develops pressure-like substernal chest pain lasting 1 hour. She works as a housekeeper; lifting and exertion have precipitated similar pain in the recent past. There is a positive family history of gallstones (mother and sister). Her ECG is shown below. Which of the following is the most likely diagnosis?

A. Costochondritis

B. Acute anterior myocardial infarction

C. Acute inferior myocardial infarction

D. Pericarditis

E. Gastroesophageal reflux

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The answer is C.

EXPLANATION: The ECG shows ST-segment elevation in inferior leads (II, III, and a VF) with reciprocal ST depression in aVL, diagnostic of an acute inferior MI. An anterior MI would produce ST-segment elevation in the precordial leads. Pericarditis classically produces pleuritic chest pain and diffuse ST segment elevation (except aVR) on ECG. Costochondritis and gastroesophageal reflux are confounding considerations raised by the history. Both can cause substernal chest pain, but not these ECG findings.

12. You are awakened in the night by your 2-year-old son, who has deve-loped noisy breathing on inspiration, marked retractions of the chest wall, flaring of the nostrils, and a barking cough. He has had a mild upper respiratory infection (URI) for 2 days. Which of the following therapies is indicated?

A. Short-acting bronchodilators and a 5-day course of steroids

B. Intubation and antibiotics

C. Observation for hypoxia and dehydration alone

D. Inhaled epinephrine and a dose of steroids

E. Rigid bronchoscopy

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The answer is D.

EXPLANATION: The signs of illness described are those involving the airway above the point at which the trachea enters the neck and leaves the thorax, resulting in inspiratory stridor such as in croup. The extrathoracic airway tends to collapse on inspiration, producing the characteristic findings this patient demonstrates; therapy usually is with a single dose of steroids. Agents causing croup include parainfluenza types 1 and 3, influenza A and B, RSV, and occasionally other viruses. Treatment is usually supportive, but racemic epinephrine and corticosteroids reduce the length of time in the emergency room and hospitalizations.

Intrathoracic airway diseases, such as asthma (bronchodilators and short course of steroids) or bronchiolitis (supportive therapy including observation for hypoxia or dehydration alone), produce breathing difficulty on expiration, with expiratory wheezing, prolonged expiration, and signs of air trapping due to the increased narrowing during expiration as the airways are exposed to the same intrathoracic pressure changes as the alveoli.

Acute airway foreign body (rigid bronchoscopy) should result in differential air movement between the two lungs. The typical case of epiglottis (intubation and antibiotics) presents acutely and the child is toxic in appearance; it is now a rare disease with the widespread use of vaccines.

Headache in children can often be a concerning symptom to parents, but usually can be explained with a careful history and physical examination. Choose the headache associated with this clinical presentation.

13. A 15-year-old girl has an acute, recurrent, pulsatile headache localized behind the eyes that tends to occur more frequently around menses. She has no symptoms that occur prior to the headache; her neurologic examination is normal.

A. Tension headache

B. Factitious headache

C. Vascular headache (migraine)

D. Increased intracranial pressure

E. Hemiplegic migraine

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The answer is C.

EXPLANATION: Headaches can be a concerning symptom in the pediatric population, especially to parents; it is a common pediatric complaint. Vascular headaches can occur in all ages, and patients usually have a family history of migraine. While the typical scotomata discussed in adult migraine is not normally associated in children with migraine, pediatric migraines may have a nonspecific prodrome consisting of a change in mood, temperament, or appetite. Worsening headaches with nausea and emesis (particularly early morning emesis) are concerning for increased intracranial pressure from a mass lesion. Other associated findings may be decreased school performance, behavioral changes, or focal neurologic deficits. Papilledema may be present. Imaging would be necessary with this presentation.

Tension headaches are common in the older child and adolescent. They will worsen during the day, and may worsen with stressful situations like tests. They are typically described as squeezing, but are not usually pulsatile. Nausea and vomiting are not typical.

Factitious headache, as with any factitious diagnosis, should be one of exclusion. Hemiplegic migraine is descriptive of a typical aura that involves unilateral sensory or motor signs with a migraine headache. Patients can have unilateral weakness, numbness, and aphasia. These signs may resolve quickly or may last for days. This particular type of migraine is more common in children than in adults.

14. A 62-year-old man is suffering from arrhythmias on the night of his triple coronary bypass. Potassium has been administered. His urine output is 20 to 30 mL/h. Serum potassium level is 6.2. Which of the following medications counteracts the effects of potassium without reducing the serum potassium level?

A. Sodium polystyrene sulfonate (Kayexalate)

B. Sodium bicarbonate

C. 50% dextrose

D. Calcium gluconate

E. Insulin

The answer is D.

EXPLANATION: Calcium gluconate does not affect the serum potassium level but rather counteracts the myocardial effects of hyperkalemia. Reduction of an elevated serum potassium level, however, is important to avoid the cardiovascular complications that ultimately culminate in cardiac arrest. Kayexalate is a cation exchange resin that is instilled into the gastrointestinal tract and exchanges sodium for potassium ions. Its use is limited to semiacute and chronic potassium elevations. Sodium bicarbonate causes a rise in serum pH and shifts potassium intracellularly. Administration of glucose initiates glycogen synthesis and uptake of potassium. Insulin can be used in conjunction with this to aid in the shift of potassium intracellularly.

15. A 4-year-old previously well African American boy is brought to the office by his aunt. She reports that he developed pallor, dark urine, and jaundice over the past few days. He stays with her, has not traveled, and has not been exposed to a jaundiced person, but he is taking trimethoprim sulfamethoxazole for otitis media. The CBC in the office shows a low hemoglobin and hematocrit, while his "stat" serum electrolytes, blood urea nitrogen (BUN), and chemistries are remarkable only for an elevation of his bilirubin levels. His aunt seems to recall his 8-year-old brother having had an "allergic reaction" to aspirin, which also caused a short-lived period of anemia and jaundice. Which of the following is the most likely cause of this patient's symptoms?

A. Hepatitis B

B. Hepatitis A

C. Hemolytic-uremic syndrome

D. Gilbert syndrome

E. Glucose-6-phosphate dehydrogenase deficiency

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The answer is E.

EXPLANATION: Synthesis of the RBC enzyme glucose-6-phosphate dehydrogenase (G6PD) is determined by genes on the X chromosome, and the pattern of inheritance is X-linked recessive. The enzyme found in most populations is termed G6PDB1. There are more than 380 deficient variants of the enzyme, affecting over 100 million people worldwide. Among them is variant G6PDA1, a mutant enzyme affecting about 13% of African American males and 2% of African American females. The disease occurs, though less commonly, in other ethnic groups, including Middle Eastern, African, and Asian groups. Deficiency of G6PD compromises the generation of reduced glutathione and upon exposure to oxidant agents such as sulfa drugs, antimalarials, nitrofurans, naphthalene mothballs, or infection, a hemolytic episode usually occurs. The degree of hemolysis depends on the nature of the oxidant and severity of the enzyme deficiency. In African Americans, the older, more G6PD-deficient cells are destroyed, but since young cells have sufficient enzyme to prevent further RBC destruction even if the inciting factor is still present, the hemolytic crisis is usually self-limited. Blood transfusion may be unnecessary. In African Americans, premature testing for the enzyme immediately after a hemolytic episode can lead to a false-negative result, since the newly produced RBCs in the circulation have a higher G6PD enzyme activity. The older RBCs containing Heinz bodies (insoluble precipitates resulting from oxidation), the "bite cells" (RBCs after the removal of the Heinz bodies), and cell fragments are removed from the circulation within 3 to 4 days. In the severe Mediterranean type, young as well as old RBCs are enzyme deficient. Recovery is signaled by the appearance of reticulocytes and a rise in hemoglobin.

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