Internal Medicine Endocrinology and Metabolism Questions and Answers — Questions and Answers
Question 1: A 58-year-old male with type 2 diabetes, hypertension, and a history of heart failure with reduced ejection fraction (HFrEF) presents for a medication review. His A1c is 7.8% on metformin and glipizide. His eGFR is 50 mL/min/1.73m². Which of the following medications should be added to his regimen to improve glycemic control and provide a mortality benefit?
- Sitagliptin
- Empagliflozin (Correct answer)
- Pioglitazone
- Insulin glargine
Correct answer: Empagliflozin
Sodium-glucose cotransporter-2 (SGLT2) inhibitors, such as empagliflozin, have demonstrated significant cardiovascular benefits in patients with type 2 diabetes and established cardiovascular disease. Clinical trials like EMPA-REG OUTCOME have shown that empagliflozin reduces the risk of cardiovascular death, all-cause mortality, and hospitalization for heart failure. Pioglitazone is contraindicated in patients with heart failure as it can cause fluid retention and exacerbate the condition. Sitagliptin (a DPP-4 inhibitor) is considered cardiovascularly neutral. Insulin glargine effectively lowers glucose but does not provide the same cardiovascular mortality benefit seen with SGLT2 inhibitors in this patient population.
Question 2: A 45-year-old female is evaluated for a 1.5 cm thyroid nodule found incidentally. Her TSH is normal. A fine-needle aspiration (FNA) returns as 'Bethesda category III: Atypia of Undetermined Significance (AUS)'. What is the most appropriate next step in management?
- Immediate total thyroidectomy
- Repeat FNA in 6-12 months
- Perform molecular testing on the FNA sample (Correct answer)
- Start suppressive levothyroxine therapy
Correct answer: Perform molecular testing on the FNA sample
For thyroid nodules with indeterminate cytology, such as Bethesda category III (Atypia of Undetermined Significance or AUS), molecular testing is recommended to further stratify the risk of malignancy. Tests like Afirma Gene Expression Classifier or ThyroSeq can help differentiate benign from potentially malignant nodules, guiding the decision between observation and diagnostic surgery. Repeating the FNA is an alternative but offers less definitive risk stratification. Immediate thyroidectomy is overly aggressive for a Bethesda III nodule, and suppressive levothyroxine therapy is not indicated for euthyroid patients with benign or indeterminate nodules.
Question 3: A 34-year-old woman presents with central obesity, facial plethora, proximal muscle weakness, and new-onset hypertension. An overnight 1-mg dexamethasone suppression test fails to suppress serum cortisol. Her plasma ACTH level is <5 pg/mL (suppressed). What is the most likely source of her condition?
- Ectopic ACTH-producing tumor
- Cushing's disease (pituitary adenoma)
- Iatrogenic steroid use
- Adrenal adenoma (Correct answer)
Correct answer: Adrenal adenoma
The clinical presentation and non-suppressed cortisol after dexamethasone confirm Cushing's syndrome. The key diagnostic finding is the suppressed plasma ACTH level. This indicates an ACTH-independent cause, meaning the adrenal gland is autonomously producing cortisol and suppressing the pituitary via negative feedback. The most common cause of ACTH-independent Cushing's syndrome is a cortisol-producing adrenal adenoma. In contrast, Cushing's disease (pituitary source) and ectopic ACTH-producing tumors would present with normal or elevated ACTH levels. Iatrogenic use would also cause a suppressed ACTH but is a diagnosis of exclusion based on history.
Question 4: Which of the following is the most significant contraindication to the use of teriparatide for the treatment of severe osteoporosis?
- Prior radiation therapy to the skeleton (Correct answer)
- History of nephrolithiasis
- Severe vitamin D deficiency
- Creatinine clearance < 30 mL/min
Correct answer: Prior radiation therapy to the skeleton
Teriparatide carries a warning regarding an increased risk of osteosarcoma, based on findings in rat studies. Therefore, it is contraindicated in patients with an increased baseline risk for osteosarcoma. This includes individuals with Paget's disease of the bone, unexplained elevations of alkaline phosphatase, and, significantly, a history of prior radiation therapy to the skeleton. While caution is advised in patients with renal impairment or a history of kidney stones, and vitamin D should be repleted before starting therapy, these are not absolute contraindications like prior skeletal radiation.
Question 5: A 72-year-old male admitted for pneumonia is found to have a serum sodium of 118 mEq/L. Further labs show serum osmolality of 255 mOsm/kg, urine osmolality of 450 mOsm/kg, and urine sodium of 50 mEq/L. He is clinically euvolemic. What is the most appropriate initial treatment for his hyponatremia?
- Aggressive normal saline (0.9%) infusion
- Fluid restriction to <1 L/day (Correct answer)
- Administration of desmopressin (DDAVP)
- Infusion of 3% hypertonic saline
Correct answer: Fluid restriction to <1 L/day
The patient's presentation of euvolemic hypotonic hyponatremia with inappropriately concentrated urine is classic for the Syndrome of Inappropriate Antidiuretic Hormone (SIADH), which is often precipitated by pulmonary infections. For mild to moderate asymptomatic or mildly symptomatic hyponatremia from SIADH, the cornerstone of initial management is free water restriction. Administering normal saline can worsen hyponatremia in SIADH. Desmopressin is used to treat central diabetes insipidus. Hypertonic saline is reserved for severe, symptomatic hyponatremia (e.g., seizures, coma).
Question 6: A 48-year-old male with treatment-resistant hypertension is found to have a serum potassium of 3.1 mEq/L despite not being on diuretics. Which of the following is the best initial screening test to investigate the most likely diagnosis?
- 24-hour urine metanephrines
- Late-night salivary cortisol
- Plasma aldosterone-renin ratio (ARR) (Correct answer)
- Renal artery duplex ultrasound
Correct answer: Plasma aldosterone-renin ratio (ARR)
The combination of treatment-resistant hypertension and spontaneous hypokalemia is highly suggestive of primary aldosteronism. The Endocrine Society guidelines recommend the plasma aldosterone-renin ratio (ARR) as the initial screening test for this condition. An elevated aldosterone level coupled with a suppressed renin level points towards autonomous aldosterone secretion. While other conditions can cause secondary hypertension, the presence of hypokalemia makes primary aldosteronism the leading diagnosis to investigate first.
Internal Medicine Endocrinology and Metabolism Questions and Answers
A 58-year-old male with type 2 diabetes, hypertension, and a history of heart failure with reduced ejection fraction (HFrEF) presents for a medication review.
His A1c is 7.8% on metformin and glipizide.
His eGFR is 50 mL/min/1.73m².
Which of the following medications should be added to his regimen to improve glycemic control and provide a mortality benefit?