USMLE Step 3 Test

The United States Medical Licensing Examination Step 3, or USMLE Step 3, is a comprehensive and challenging assessment for men and women who wish to enter the exciting field of medical science. The test consists of 480 multiple-choice questions, each of which has five possible answers.

The questions are broken up into blocks of 35 to 50, with 45 to 60 minutes allotted for each block. The exam also includes nine computer-based case simulations, each of which must be completed in fewer than 25 minutes. There are two ways of looking at the content of the USMLE Step 3: by clinical encounter frame and by physician task.

There are three clinical encounter frames on the examination: initial care (20 to 30 percent of the exam); continued care (50 to 60 percent); and emergency care (15 to 25 percent). At the same time, there are six physician tasks covered: obtaining a history and performing a physical examination (8 to 12 percent of the exam); using laboratory and diagnostic studies (8 to 12 percent); formulating the most likely diagnosis (8 to 12 percent); evaluating the severity of the patient’s problems (8 to 12 percent); applying scientific concepts and mechanisms of disease (8 to 12 percent); and managing the patient (45 to 55 percent).

The raw score (the number of questions answered correctly) is placed on both a three-digit and two-digit scale because different jurisdictions require different scaled scores for the USMLE Step 3 test. Most three-digit scaled scores are between 140 and 260, and the typical minimum passing score on the two-digit scale is 75.

USMLE Step 3 Test Practice Questions

1. He is advised to stop the aspirin and naproxen and to report any obvious rectal bleeding. He is then referred to a gastroenterologist for further workup.

What should be the next diagnostic procedure?

a. Upper gastrointestinal endoscopy (EGD)
b. Colonoscopy
c. Both EGD and colonoscopy
d. Angiography
e. Air contrast barium enema

2. The patient undergoes both upper and lower endoscopy but no bleeding lesion or clot is noted. No gastric or duodenal ulcer is seen and the esophageal mucosa appears intact. He has scattered diverticula and a few small colonic polyps that are removed and reported as benign by pathology. A repeat EGD remains negative but occult blood in the stool tests remain positive.

What should be the next diagnostic step?

a. Isotopic red blood cell scan
b. Surgical intraoperative enteroscopy
c. Angiography
d. Capsule endoscopy
e. Push enteroscopy

3. A 45-year-old man comes to see you because his wife insists that he gets a physical. He feels well but has gained some weight over the past 10 to 15 years and gets little exercise. He is an attorney and is usually too busy to worry about his diet. He had a melanoma removed from his arm about 8 years ago. His mother has high blood pressure and diabetes and his father died of an apparent heart attack in his late 50s. His blood pressure is 140/88, regular pulse, afebrile, and BMR of 30.2 kg/m. A surgical scar from the melanoma excision is present on his left forearm but no suspect lesions are noted on skin exam. His physical examination is fairly unremarkable except for abdominal obesity with a waist/hip ratio of 1.3. An electrocardiogram is normal. Blood tests and urinalysis are unremarkable except for a fasting glucose of 180 mg/dL and a hemoglobin A1c of 7.8%

What is the most appropriate treatment for this patient now?

a. Referral to a dietician for a low-carbohydrate diet and an exercise program
b. Answer A and start metformin
c. Answer A and start a sulfonylurea
d. Answer A and start a thiazolidinedione
e. Answer A and start insulin

4. The patient is seen 3 months after his initial visit. He has lost only 2 lb. He says he is too busy with a big case to follow a diet or get much exercise. His blood pressure is now 150/90, the total cholesterol 280 mg/dL with an LDL-C of 140 mg/dL and an HDL-C of 35 mg/dL. The triglycerides are 400 mg/dL. His hemoglobin A1c is 7.6%

What treatment is most appropriate now?

a. Begin metformin
b. Begin metformin and a statin
c. Begin a sulfonylurea and a statin
d. Begin a diuretic or beta-blocker
e. Begin insulin

5. Six months later, the patient is taking a statin, metformin, and losartan. His blood pressure is now 130/80, his LDL-C is 100 mg/dL, and the hemoglobin A1c is 6.8. He has lost about 5 lb. The following year, on the same therapy, his numbers are as follows: blood pressure 135/85, LDL-C 90 mg/dL, HDL-C 40 mg/dL, and hemoglobin A1c 8.5%. He now complains of fatigue and occasional thirst and polyuria.

What action should you take now?

a. Add a sulfonylurea
b. Add a nonsulfonylurea secretagogue
c. Add a thiazolidinedione
d. Add an alpha-glucosidase inhibitor
e. Any of the above and consider adding long-acting niacin

Answers

1. C. Both the upper and lower gastrointestinal tract should be examined in patients with occult blood loss since there may be more than 1 lesion. This is often done one after another for patient convenience and to avoid giving anesthesia twice. Barium enema is now rarely used since colonoscopy can identify a bleeding lesion or clot and take a biopsy and/or coagulate it. Angiography is useful for brisk bleeding lesions (at least 1 mL/min) when endoscopy has failed to detect the source or is obscured by blood.

2. D. Capsule endoscopy (patient swallows a small camera within an ingestible capsule and images are transmitted to a receiver on the patient’s abdomen for review) has a good diagnostic yield (60% to 90%) in occult bleeding cases in which traditional endoscopy has failed to detect a lesion. Angiography is mostly useful for rapid bleeding. Isotope tagged red blood cell scintigraphy may identify the site of gastrointestinal bleeding at lower blood flows (0.1 mL/min) but cannot determine the cause. Push enteroscopy of the small bowel has a yield of 38% to 75% and may be tried if the bleeding is not rapid. If all of the above fail to disclose the source and bleeding continues, surgical intervention with intraoperative enteroscopy may be tried. In all cases, iron therapy and follow-up hemoglobin values should be carried out with transfusion if necessary.

3. A. Asymptomatic but overweight diabetic patients with a hemoglobin A1c less than 8% should probably be given a short trial of diet and exercise before beginning hypoglycemic therapy. The current guidelines from the American Diabetes Association require reduction to less than 7%. Some other authorities demand a reduction to less than 6.5%, although a recent clinical trial indicates that too aggressive treatment may be counterproductive. The patient should be seen at 3- to 4-month intervals with follow-up blood testing. Monitoring of blood pressure, lipid levels, and abdominal girth is also recommended. If glycemic control is not achieved, metformin or one of the others may be started.

4. B. It is clear that this patient is unlikely to be controlled on diet and exercise, so hypoglycemic therapy is indicated. His weight, abdominal girth, elevated blood pressure, high triglycerides, and low HDL-C suggest he has “metabolic syndrome,” although this designation is somewhat controversial. He needs reduction of his LDL-C and hemoglobin A1c, as well as his blood pressure. The best approach would be to begin metformin and a statin immediately, and save introduction of an antihypertensive at a follow-up visit as starting three drugs at once may obscure adverse effects or cause noncompliance. Most doctors would choose metformin for this patient since it does not cause weight gain and has been shown to reduce macrovascular complications of diabetes mellitus. Using a sulfonylurea is a second choice since it tends to increase weight and it is an insulin secretagogue, and the likelihood of hypoglycemic episodes is greater than with metformin. Insulin may ultimately be required in type 2 diabetic patients but a trial of oral therapy is preferred for a patient such as this. When antihypertensive therapy is started, an ACE inhibitor or an ARB would be preferable to a beta-blocker or diuretic since the latter drugs have a tendency to raise the blood sugar, though modestly. A reduction to less than 140 mm Hg systolic is advisable.

5. E. This patient now has mild symptoms and his glycohemoglobin has risen to greater than 8%. Some doctors would begin insulin at this point but most authorities suggest a trial of a second daytime oral drug. The exact type depends on the patient’s compliance, cost of the medication, and adverse effects. Sooner or later most patients fail on oral therapy but many doctors would try a third agent from a different class before submitting the patient to the nuisance and hazards of insulin. Use of a daytime sulfonylurea and bedtime insulin is a popular regimen instead of adding a third oral drug. Adding long-acting niacin may be considered to try to raise the HDL-C and lower triglycerides but liver function tests must be followed.

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By Lindsay Downs

Last Updated: 06/20/2014

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