USMLE USMLE-STEP-3 Exam Questions & Answers

Correct Answer: A Section: (none)

Explanation:

This is a clinical presentation of West Nile virus infection. The tongue fasciculations go along with an inflammation at the base of the brain. The patient is at the right age for West Nile virus infection and he is immunocompromised due to diabetes. The diagnosis can be made by performing a West Nile virus IgM titer on the CSF. Diabetics can have cryptococcal meningitis. Lumbar puncture in this setting is usually normal with increased opening pressure, and rhabdomyolysis is not a feature of this disease. Diabetics are more at risk for candidiasis. However, the patient has no history of instrumentation, IV catheters, or other situations that would lead to disseminated candidiasis. Diabetics are at increased risk for C. immitis infection, but we have no history of the patient living in an area endemic for this organism. Diabetics are at increased risk for rhinocerebral mucormycosis. An MRI of the head might have shown involvement of the sinus. However, this patient's presentation is not consistent with rhinocerebral mucormycosis.

Correct Answer: B Section: (none)

Explanation:

Cholelithiasis is much more common in women than men. In addition to gender, the development of gallstones can also be affected by age, weight, family history, and pregnancy. Gallstones often remain asymptomatic, but they can cause symptoms when they cause obstruction of the cystic duct. The result of this obstruction is biliary colic, which is experienced as epigastric pain radiating to the back and can be associated with nausea and vomiting. The presence of tenderness to palpation in the right upper quadrant, fever, and leukocytosis would suggest acute cholecystitis, a complication of gallstones. In a patient suspected of having complications of gallstones, the best test for evaluation is ultrasonography. Ultrasonography is highly sensitive in detecting gallstones and also provides details about the thickness of the gallbladder wall, the presence of pericholecystic fluid, and also the presence or absence of tenderness over the gallbladder during the examination (sonographic Murphy's sign). A two-way roentgenogram of the abdomen is much less sensitive, detecting only 20% of gallstones. A CT scan of the abdomen with IV and PO contrast can be sensitive in detecting the inflammatory changes associated with acute cholecystitis, but it is much more expensive and time consuming when compared to ultrasound. A HIDA scan, although sensitive and specific in the right setting, is generally reserved for more complicated cases where the diagnosis is unclear. Failure to visualize the gallbladder with HIDA scan in 1 hour indicates either partial or complete cystic duct obstruction and confirms the diagnosis of acute cholecystitis. However, this should not be the first-line test in evaluating a patient for acute cholecystitis. Finally, an MRCP can be very useful in evaluating the biliary tree and the presence of choledocholithiasis in a patient with cholecystitis and an elevated bilirubin, but does not have a role in the diagnosis of acute cholecystitis

Correct Answer: A Section: (none)

Explanation:

Parathormone (PTH), with vitamin D, is a major regulator of the serum levels of calcium. PTH is made in the chief cells of the four parathyroid glands and exerts effects mainly on the bone and kidneys to maintain adequate serum levels of calcium.