If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 2 exam, you might want to know which questions are most often missed by test-prep takers. Check out this example from Kaplan Medical, and read an expert explanation of the answer. Also check out all posts in this series.
This month’s stumper
A 48-year-old man comes to the physician for a routine health maintenance examination. He has had no chest pain, shortness of breath or palpitations. His medical history is unremarkable and he takes no medications. He does not smoke cigarettes, drink alcohol or use illicit drugs. He weighs 203 pounds and he is 5 feet 8 inches tall. Body mass index is 29. His blood pressure is 145/82 mm Hg and his pulse is 92/minute. Examination shows no other abnormalities. Serum electrolyte levels, complete blood count and cholesterol levels are within normal limits.
Which of the following screening tests is most appropriate in this patient?
A. Measurement of C-reactive protein.
B. Measurement of erythrocyte sedimentation rate.
C. Measurement of fasting plasma glucose.
D. Measurement of homocysteine.
E. Measurement of lipoprotein (a).
The correct answer is C.
Kaplan Medical explains why
The American Diabetes Association (ADA) recommends screening for diabetes or prediabetes in all adults who have a BMI greater than 25. According to the ADA, all adults older than 45 should be screened for diabetes. The U.S. Preventive Services Task Force concluded that there is insufficient evidence to perform routine screening in healthy adults; however, screening for diabetes in patients with hypertension is recommended to assess cardiovascular risk. This patient does have hypertension and thus warrants screening for diabetes, even by conservative standards.
Why the other answers are wrong
Choice A: Measurement of C-reactive protein in patients who have heart disease has shown a relationship with elevated protein levels. These are considered to be "putative" risk factors. Measurement of C-reactive protein is not used as a routine screening test.
Choice B: Elevated erythrocyte sedimentation rate is an indication of inflammation. There is no history or physical examination findings to suggest an inflammatory process.
Choice D: Homocysteine has gained recent attention for its relationship with carotid disease. It has not yet been accepted, however, as a routine measure for assessing coronary disease risk.
Choice E: Similarly, lipoprotein (a) may be elevated in patients who have heart disease. This is not considered a traditional risk factor, however, and thus is not routinely screened.
Tips to remember
Screening for diabetes or prediabetes is appropriate for those with the following risk factors: Older than 45, or overweight and older than 45 with one or more of the following risk factors:
- High blood pressure.
- Parent, grandparent or sibling with diabetes.
- History of gestational diabetes or of an infant weighing more than 9 pounds at birth
- Polycystic ovary syndrome.
- High triglycerides or low HDL cholesterol.
- Certain ethnic groups: Native American, Latino, Pacific Islander, Asian-American or African-American
For more prep questions on USMLE Steps 1, 2 and 3, view other posts in this series.
