ABFM CKSA 24-25 Exam Study Guide 150 Questions with Correct Answers Explained

ABFM CKSA 24-25 Exam Study Guide 150 Questions with Correct Answers A 56-year-old male with a history of hepatitis C cirrhosis is admitted to the hospital with GI bleeding. The patient has been stable, taking only furosemide and spironolactone. Upper GI endoscopy confirms variceal bleeding and the gastroenterologist performs appropriate variceal banding. A nurse calls you because laboratory studies ordered in the emergency department reveal a serum ammonia level of 120 µg/dL (N 39-90). The patient has no signs of confusion, insomnia, or decreased mental alertness. A physical examination reveals mild ascites but no other abnormalities. Which one of the following would be most appropriate for addressing the elevated ammonia level? A. Lactulose B. No additional treatment C. Methotrexate D. Neomycin E. Prednisone - Correct Answer ANSWER: B Elevated ammonia levels may occur in multiple clinical scenarios (i.e. portosystemic shunting, UTI from urease-producing organisms, GI bleeding, shock, renal disease, parenteral nutrition, salicylate intoxication, alcohol use). In patients with chronic liver disease, hepatic encephalopathy is diagnosed based on the overall clinical presentation and not by an ammonia level. It is important to remember that a normal ammonia level neither excludes nor confirms the diagnosis of hepatic encephalopathy. This patient had an elevated serum ammonia level that was found incidentally during his hospital admission for gastrointestinal bleeding. Because there is no clinically significant encephalopathy, treatment based on ammonia levels is not indicated. Lactulose, methotrexate, neomycin, or prednisone would not be appropriate. A 33-year-old female presents with palpitations and excessive sweating. A physical examination is normal. Laboratory findings include a TSH (thyrotropin) level of 0.02 µU/mL (N 0.40-4.00) and a free T4 level of 3.9 ng/dL (N 0.7-1.9). Radionuclide scanning reveals no uptake. Which one of the following would explain these findings? A. Thyroid hormone resistance B. Graves disease C. A toxic nodular goiter D. Excess thyroid hormone intake E. A thyrotropin-secreting pituitary tumor - Correct Answer ANSWER: D Excess thyroid hormone intake would cause a low TSH (thyrotropin) level with a high free T4 level and no uptake on radionuclide scan. Other possibilities include an hCG-secreting tumor and the thyrotoxic phase of subacute thyroiditis.