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Step 2 Wed - USMLERx Step 2CK Question #21271

Sumeet — Wed, 08 Jul 2009 05:00:27 +0000

Which of the following laboratory findings are characteristic of hemophilia B? PT refers to prothrombin time and aPTT refers to activated partial thromboplastin time.

A. A
B. B
C. C
D. D
E. E

The correct answer is B. This profile is consistent with hemophilia B. Hemophilia B (Christmas disease) is an X-linked recessive coagulopathy involving a deficiency of coagulation factor IX that may lead to mild to severe bleeding, depending on the factor activity. A prolonged activated partial thromboplastin time is seen with hemophilia. Prothrombin time, bleeding time, and platelet count are expected to be normal in a patient with hemophilia.

Answer A is not correct. This is a normal profile and is not consistent with the diagnosis of hemophilia.

Answer C is not correct. This profile is consistent with hemophilia A. Hemophilia A is an X-linked recessive coagulopathy involving a deficiency in coagulation factor VIII that may lead to mild to severe bleeding, depending on the factor activity. A prolonged activated partial thromboplastin time is seen with hemophilia. Prothrombin time, bleeding time, and platelet count are expected to be normal in a patient with hemophilia.

Answer D is not correct. This profile is consistent with von Willebrand’s disease (vWD). vWD is an autosomal dominant genetic defect in von Willebrand factor, which both mediates platelet binding to damaged endothelium and binds/stabilizes factor VIII. Patients with vWD typically present with a prolonged bleeding time, a prolonged activated partial thromboplastin time, and a factor VIII deficiency.

Answer E is not correct. This profile is consistent with thrombocytopenia, as seen with disorders such as idiopathic thrombocytopenic purpura or heparin-induced thrombocytopenia.

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Q&A Monday - USMLERx Step 1 Question #1005

Sumeet — Mon, 06 Jul 2009 05:00:48 +0000

A 56-year-old obese man comes to the emergency department because of crushing chest pain that has been present for 3 hours. The pain radiates to his left arm and neck. He also complains of nausea. On physical examination, the patient is found to be sweating and his blood pressure is 164/122 mm Hg. Laboratory analysis reveals that his cardiac enzyme levels are elevated. His ECG is abnormal with ST-segment depression. Which of the following is the pathology underlying the correct diagnosis?

A. Coronary artery vasospasm caused by cigarettes and cocaine
B. Complete occlusion of the coronary arteries by a mural thrombus
C. Increased cardiac demand with coronary arteries that are greater than 75% occluded
D. Ischemic necrosis of 30% of the ventricular wall
E. Ischemic necrosis of 70% of the venricular wall

The correct answer is D. The patient has a subendocardial infarction, which is caused by ischemic necrosis of <50% of the ventricular wall. This area of the myocardium is the last section of the myocardium to be perfused and, as a result, is the first to undergo necrosis from prolonged ischemia. Ischemia is typically due to diffuse atherosclerosis or a transient thrombosis.

Answer A is not correct. Coronary artery vasospasm is a condition known as Prinzmetal’s variant angina. It is characterized by variant pain at rest and transient ST-segment elevation on ECG.

Answer B is not correct. A complete occlusion of the coronary arteries causes transmural infarcts. On ECG, there is a corresponding ST-segment elevation.

Answer C is not correct. Stable angina is characterized by chest pain that arises with physical exertion or stress and passes with rest or decreased stress level. It is often due to >75% occlusion of the coronary arteries by atherosclerosis. Although stable angina may produce slightly elevated cardiac enzyme levels, the clinical picture in this question is more typical of a myocardial infarction.

Answer E is not correct. Ischemic necrosis of >50% of the ventricular wall causes a transmural infarct. On ECG, there is a corresponding ST-segment elevation.

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This practice question is an actual question from the USMLERx Step 1 test bank.

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New College-Loan Plan: Pay Back Based on What You Earn

Sumeet — Sun, 05 Jul 2009 05:00:41 +0000

Starting July 1, repayment is set to change to Income Based Repayment. This will affect our ability to defer loans in residency and affect repayment later on as well.

Alcohol’s Good for You? Some Scientists Doubt It

Sumeet — Fri, 03 Jul 2009 05:00:15 +0000

Study after study suggests that alcohol in moderation may promote heart health and even ward off diabetes and dementia. The evidence is so plentiful that some experts consider moderate drinking — about one drink a day for women, about two for men — a central component of a healthy lifestyle. But what if that's all a big mistake?

Step 2 Wed - USMLERx Step 2CK Question #21328

Sumeet — Wed, 01 Jul 2009 12:10:42 +0000

A 32-year-old man is stabbed in the left chest and presents to the emergency department in distress. His pulse is 130/min, blood pressure is 70/50 mm Hg, and respiratory rate is 39/min. The stab wound is in the left fifth intercostal space in the midaxillary line. On examination his trachea is deviated to the right, jugular veins are distended bilaterally, and he has absent breath sounds and hyperresonance to percussion on the left side. Subcutaneous emphysema is palpated on the left thoracic wall. What is the best next step in management?

A. Needle thoracostomy
B. Chest tube thoracotomy
C. Pericardiocentesis
D. Surgical exploration
E. Diagnostic peritoneal lavage

The correct answer is A. This patient presented with a tension pneumothorax, which results from a parenchymal wound that acts as a one-way valve that allows free air into the pleural space but prevents its escape, causing collapse of the lung on the affected side. It is a medical emergency, as the building pressure in the pleural space causes shifting or displacement of the mediastinum to the contralateral side and subsequently compromises cardiopulmonary function. Compression of the opposite lung impairs proper gas exchange while impingement on the heart impairs proper cardiac function. The most common mechanisms of this type of injury are blunt or penetrating injuries, or secondary to medical procedures. A large-bore needle should be inserted in the second intercostal space in the midclavicular line to facilitate decompression and reestablish cardiopulmonary function. The needle is left in place until a thoracostomy tube can be inserted.

Answer B is not correct. Although tube thoracotomy is also needed, tension pneumothorax is a medical emergency and demands urgent decompression. A large release of air after needle insertion confirms the diagnosis, and can then be followed by a thoracostomy. The chest tube is then attached to a vacuum to continuously remove air from the pleural cavity until the parenchyma heals.

Answer C is not correct. Pericardiocentesis is the treatment of choice for cardiac tamponade, which can also present with tachycardia, jugular venous distention, and decreased blood pressure. However, the location of the wound, the tracheal deviation, absent breath sounds, hyperresonance to percussion, and severity of dyspnea suggest tension pneumothorax.

Answer D is not correct. Exploratory thoracotomy is the treatment for massive hemothorax. However, tension pneumothorax is best managed with needle thoracostomy followed by tube thoracotomy.

Answer E is not correct. The location of the wound in the fifth intercostal space implies that abdominal injury is possible. However, in following the ABCs as part of the Advanced Trauma Life Support protocol, breathing must be adequately treated before evaluating circulation and proceeding to a diagnostic peritoneal lavage.

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This practice question is an actual question from the USMLERx Step 2CK test bank.

Purchasing a USMLERx Subscription provides many more features, more questions, and passages from First Aid relevant to the question.

Q&A Monday - USMLERx Step 1 Question

Sumeet — Mon, 29 Jun 2009 05:00:37 +0000

A 60-year-old man with recurrent bacterial sepsis is hospitalized in order to receive intravenous antibiotics. He is started on his fourth course of broad-spectrum antibiotics within the past month. Three days into the admission, his nurse notes that his venous access is oozing blood. Laboratory tests reveal a prolonged prothrombin time, a prolonged partial thromboplastin time, and a normal platelet count. Which of the following coagulation cofactors would be deficient first in this patient?

A. Factor II
B. Factor V
C. Factor VII
D. Factor VIII
E. Factor XI
F. Factor XII

The correct answer is C. Vitamin K is synthesized by the intestinal flora; therefore long-term treatment with broad-spectrum antibiotics can induce a vitamin K deficiency by clearing intestinal flora. Vitamin K is a necessary cofactor for hepatic production of clotting factors II, VII, IX, and X and proteins C and S. Factor VII has the shortest half-life of all clotting factors (4-6 hours), which is why the prothrombin time is prolonged first in vitamin K deficiency.

Answer A is not correct. Factor II requires vitamin K as a cofactor, and early factor II deficiency would result in prolongation of prothrombin time and partial thromboplastin time. However, the half-life of factor II is 42-72 hours, and thus it would not be deficient before factor VII is deficient.

Answer B is not correct. Vitamin K is not required for factor V synthesis and would not be deficient in this patient.

Answer D is not correct. Factor VIII is not a vitamin K dependent clotting factor.

Answer E is not correct. Factor XI is not a vitamin K dependent clotting factor.

Answer F is not correct. Factor XII is not a vitamin K dependent clotting factor.

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This practice question is an actual question from the USMLERx Step 1 test bank.

Purchasing a USMLERx Subscription provides many more features, more questions, and passages from First Aid relevant to the question.

Article: How to Cut Health-Care Costs: Less Care, More Data

Sumeet — Sat, 27 Jun 2009 05:00:10 +0000

The best, least biased, article about the Health Care situation that I’ve seen in years. Worth reading from beginning to end.

Please Click here for the Article

The ultimate success of Obamacare might depend on a cultural change among doctors and patients, a national realization that more care isn’t better care. “We’ve got this ethos that the best doctors do everything under the sun and rule out every zebra,” Emanuel says. “And hey, they get paid more to do it. But we’ve got to change all that.”

Article: Kid Goes Into McDonald’s and Orders … Yogurt?

Sumeet — Fri, 26 Jun 2009 05:00:18 +0000

The eating habits of American children appear to be shifting. And for a change, the news is good.

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Step 2 Wed - USMLERx Step 2CK Question #21018

Sumeet — Wed, 24 Jun 2009 05:00:48 +0000

A 30-year-old woman presents to a primary care physician for a new patient visit. She reports recurrent episodes of pneumonia, bronchitis, and otitis over the past 4 years. Although her vaccinations were up to date, she developed tetanus following a foot laceration last year. Her lymph nodes and tonsils are enlarged. Laboratory testing reveals low IgG, IgA, and IgM levels. After referral to a hematologist, who rules out other acquired and genetic causes of her hypogammaglobulinemia, she is diagnosed with common variable immunodeficiency. This woman is at the highest risk of developing which of the following condition?

A. Cardiovascular disease
B. Lymphoma
C. Miscarriage
D. Renal disease
E. Splenic autoinfarction

The correct answer is B. Common variable immunodeficiency (CVID) is a syndrome characterized by hypogammaglobulinemia in combination with phenotypically normal B lymphocytes. The disease presents suddenly in the third or fourth decade after recurrent infections and lack of response to vaccines. It is a diagnosis of exclusion, and its pathogenesis is not well understood. Women in their fifth and sixth decades of life with CVID are at a 438-fold increased risk of developing lymphoma. In addition to malignancy, patients with CVID are at increased risk of chronic lung disease, autoimmune phenomenon, and chronic diarrhea.

Answer A is not correct. Patients with CVID are not at increased risk of cardiovascular disease, although they are at greater risk for chronic lung disease (most commonly bronchiectasis).

Answer C is not correct. The risk of miscarriage is not increased in patients with CVID.

Answer D is not correct. There is no association between CVID and renal disease.

Answer E is not correct. Twenty-five percent of patients with CVID have splenomegaly. However, there is no evidence that patients with CVID are more likely to autoinfarct their spleens.

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This practice question is an actual question from the USMLERx Step 2CK test bank.

Purchasing a USMLERx Subscription provides many more features, more questions, and passages from First Aid relevant to the question.

Q&A Monday - USMLERx Step 1 Question

Sumeet — Mon, 22 Jun 2009 05:00:19 +0000

A mutation in the elongation factor EF1-?, which is essential for protein synthesis, causes it to have a higher affinity for GDP than normal. This decreases the growth rate of the cells due to a decrease in protein synthesis. A secondary mutation in the cells increases the growth rate back toward normal. Which of the following is the secondary mutation?

A. Decreased affinity of elongation factor EF1-? for guanosine triphosphate
B. Decreased affinity of elongation factor EF1-? for guanosine triphosphate
C. Elimination of EF1-?
D. Elimination of EF1-?
E. Increased affinity of elongation factor EF1-? for the mutant EF1-?

The correct answer is E. Before binding mRNA, aminoacyl-tRNA first binds guanosine triphosphate (GTP) and elongation factor EF1-?. When tRNA binds to the A site of the ribosome, GTP is hydrolyzed to guanosine diphosphate (GDP). The GDP-EF1-? complex then binds elongation factor EF-?, allowing GDP to be released. Next, GTP binds the complex and EF-? disassociates, leaving GTP-EF1-? regenerated for another cycle. Therefore, increased affinity of EF1-? for the mutant EF1-? counteracts the increased affinity of EF1-? for GDP.

Answer A is not correct. Decreased affinity of elongation factor EF1-? for guanosine triphosphate would decrease protein synthesis even further.

Answer B is not correct. Decreased affinity of elongation factor EF1-? for guanosine triphosphate would decrease protein synthesis.

Answer C is not correct. Elimination of elongation factor EF1-? would completely halt protein synthesis.

Answer D is not correct. Elimination of elongation factor EF1-? would completely halt protein synthesis.

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This practice question is an actual question from the USMLERx Step 1 test bank.

Purchasing a USMLERx Subscription provides many more features, more questions, and passages from First Aid relevant to the question.