Endocrinology and Metabolism Flashcards
6 cards from real Internal Medicine Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Endocrinology and Metabolism flashcards as text
A 68-year-old male with a 10-year history of type 2 diabetes mellitus, hypertension, and a previous myocardial infarction is seen for follow-up. His current HbA1c is 8.2% on metformin 1000 mg twice daily. His eGFR is 70 mL/min/1.73m². According to current ADA guidelines, which of the following is the most appropriate medication to add to his regimen?
Answer: Empagliflozin
For patients with type 2 diabetes and established atherosclerotic cardiovascular disease (ASCVD), guidelines strongly recommend adding an agent with proven cardiovascular benefit. SGLT2 inhibitors (like empagliflozin) and GLP-1 receptor agonists have demonstrated significant reductions in major adverse cardiovascular events. Sulfonylureas (glipizide) and DPP-4 inhibitors (sitagliptin) are generally considered to have a neutral effect on cardiovascular outcomes, while thiazolidinediones (pioglitazone) can carry a risk of worsening heart failure.
A 52-year-old male is evaluated for resistant hypertension and is found to have a serum potassium of 3.2 mEq/L. Primary aldosteronism is suspected. What is the most appropriate initial screening test for this condition?
Answer: Morning plasma aldosterone concentration and plasma renin activity
The Endocrine Society recommends screening for primary aldosteronism in patients with resistant hypertension and hypokalemia by measuring the morning plasma aldosterone concentration (PAC) and plasma renin activity (PRA) to calculate the aldosterone-to-renin ratio (ARR). An elevated ARR is a positive screen, prompting further confirmatory testing. An abdominal CT scan is used for subtype localization (e.g., adenoma vs. hyperplasia) after the biochemical diagnosis is established. The other tests are used to screen for Cushing's syndrome.
An asymptomatic 72-year-old woman is found to have a serum calcium of 11.4 mg/dL (normal 8.6-10.3 mg/dL) on routine labs. Which of the following findings would most strongly suggest primary hyperparathyroidism as the cause of her hypercalcemia?
Answer: An elevated or inappropriately normal intact parathyroid hormone (PTH) level
Primary hyperparathyroidism is characterized by the autonomous production of PTH from one or more parathyroid glands. This leads to hypercalcemia, and the feedback loop is broken. Therefore, the hallmark finding is an elevated calcium level with a simultaneously elevated or inappropriately normal PTH level. A suppressed PTH would suggest a non-PTH-mediated cause of hypercalcemia, such as malignancy, which is often driven by PTHrP. Low urine calcium suggests familial hypocalciuric hypercalcemia (FHH).
A 65-year-old man with a history of small cell lung cancer is admitted with confusion. His serum sodium is 118 mEq/L. He is clinically euvolemic. Further labs show serum osmolality of 250 mOsm/kg, urine osmolality of 400 mOsm/kg, and urine sodium of 50 mEq/L. Which of the following is the most appropriate immediate treatment?
Answer: Intravenous infusion of 3% hypertonic saline
This patient has severe, symptomatic hyponatremia due to the Syndrome of Inappropriate Antidiuretic Hormone (SIADH), a known paraneoplastic syndrome of small cell lung cancer. The presence of neurologic symptoms (confusion) necessitates urgent but controlled correction of the serum sodium to prevent further cerebral edema. The standard of care for this is an intravenous infusion of 3% hypertonic saline. Fluid restriction is the primary treatment for mild or asymptomatic SIADH, while 0.9% saline would worsen the hyponatremia. Demeclocycline is a second-line option for chronic management.
A 78-year-old female is diagnosed with osteoporosis after a DEXA scan reveals a T-score of -2.9 at the femoral neck. Her medical history is significant for severe gastroesophageal reflux disease (GERD) and erosive esophagitis. Which of the following is the LEAST appropriate initial treatment for her osteoporosis?
Answer: Oral alendronate
Oral bisphosphonates, such as alendronate, are known to cause significant upper gastrointestinal irritation, including esophagitis, esophageal erosions, and ulcers. Their use is relatively contraindicated in patients with pre-existing severe esophageal disease like erosive esophagitis. Safer and more appropriate alternatives in this patient would include non-oral options like intravenous zoledronic acid (an IV bisphosphonate), subcutaneous denosumab (a RANKL inhibitor), or subcutaneous teriparatide (an anabolic agent).
A 34-year-old female is diagnosed with Graves' disease and is started on methimazole. Which of the following best describes the primary mechanism of action of this medication?
Answer: Inhibiting the thyroid peroxidase enzyme, thus blocking hormone synthesis
Thionamides, which include methimazole and propylthiouracil (PTU), work by inhibiting the thyroid peroxidase (TPO) enzyme. TPO is essential for catalyzing the organification of iodide and the coupling of iodotyrosines to form T4 and T3. By blocking this enzyme, thionamides effectively decrease the synthesis of new thyroid hormones. While PTU also weakly inhibits the peripheral conversion of T4 to T3, this is not the primary mechanism of action for methimazole.