USMLE-STEP-3 Exam Questions & Answers

Correct Answer: D Section: (none)

Explanation:

Osteoporosis is generally defined as a T score of -2.5 SD or greater on assessment of BMD. Osteopenia is generally defined as a T score between 1 and 2.5 SD below the peak BMD for a healthy young person of the same gender. Osteoporosis screening with an assessment of BMD should be offered to the following groups: · All women 65 years old or older · All adult women with a history of a fracture (or fractures) not caused by severe trauma (such as a motor vehicle accident) · Younger postmenopausal women who have clinical risk factors for fractures · Modifiable risk factors: current cigarette smoking, low body weight (<127 lbs), estrogen deficiency, premature menopause, excessive thyroid hormone replacement, chronic corticosteroid therapy, low calcium intake (life-long), alcoholism, uncorrected visual impairment, inadequate physical activity, recurrent falls · Nonmodifiable risk factors: personal or family history of fragility, family history of osteoporosis, White or Asian race, age, gender, poor health/frailty, dementia, hypogonadism in males, fracture without substantial trauma Serial assessments for BMD may be useful but one must remember the precision error among the tests. Using DEXA, a BMD must have a 35% difference to be clinically significant. Patients who are on pharmacologic treatment with bisphosphonates may only show this much change in 1 year. Therefore, static BMD or slight reduction should not be regarded as treatment failure. At present, there are no hard evidencebased guidelines for the most efficient use for BMD monitoring. However, the following guidelines are generally accepted: · For patients with "normal" baseline BMD (T score more than -1.0), consider a followup measurement every 35 years. Patients whose bone density is well above the minimal acceptable level may not need further bone density testing. · For patients in an osteoporosis prevention program, perform a follow-up measurement every 12 years until bone mass stability is documented. After BMD has stabilized, perform follow-up measurements every 23 years. · For patients on a therapeutic program, perform a follow-up measurement yearly for 2 years. If bone mass has stabilized after 2 years, perform a follow-up measurement every 2 years. Otherwise, continue with annual follow-up measurements until stability of bone mass is achieved.

Correct Answer: C Section: (none)

Explanation:

The patient has a strong family history of thyroid cancer and has a thyroid nodule, hypertension, tachycardia, and hypercalcemia. These are hallmarks of Multiple Endocrine Neoplasia Type 2 (MEN2) syndrome, which is associated with medullary thyroid cancer, pheochromocytoma, and hyperparathyroidism. The very high calcitonin level is an excellent tumor marker for medullary thyroid cancer and a fine needle aspiration is not indicated. She will need to have an evaluation and treatment for pheochromocytoma prior to treatment of her thyroid cancer.

Correct Answer: C Section: (none)

Explanation:

The patient has chronic diarrhea superimposed on a long history of loose stools, steatorrhea, and significant weight loss. While these features could be seen in several diseases, the presence of the pruritic vesiculopapular lesions on his extensor surfaces makes the diagnosis highly likely to be celiac sprue, with its frequently accompanying skin manifestation dermatitis herpetiformis. Crohn's disease is not usually associated with steatorrhea, and ulcerative colitis is often associated with bloody stools. Chronic pancreatitis and Whipple disease could cause a similar clinical picture but would not have the associated skin findings. A small bowel biopsy would confirm histopathologic features consistent with celiac sprue, such as villous atrophy and crypt hyperplasia. A small bowel biopsy could also diagnose or rule out Whipple disease by looking for the pathognomonic PAS (periodic acid-Schiff) positive organism Tropheryma whippelii. Colonic biopsies would be unhelpful in celiac sprue. A fecal fat quantification would likely confirm and assess the degree of steatorrhea, but would offer little other diagnostic information. A small bowel x-ray is too nonspecific to confirm the diagnosis and an abdominal CT scan would likely be normal unless the patient had developed a complication of advanced sprue, such as intestinal lymphoma. Patients with celiac sprue are at increased risk for malignancies of the small bowel with adenocarcinoma and lymphoma being the two most commonly encountered. Patients with celiac sprue are not at greatly increased risk of the other malignancies listed. Limited data suggest that strict adherence to a glutenfree diet may decrease the incidence of malignancy in these patients.