Vignette Questions Flashcards
Case
An obese 45-year-old woman is requesting medical weight loss therapy. She reports excessive weight gain of (37 kg) over the past 3 years. A detailed history also reveals easy bruising, oligomenorrhea, and increased hair growth on various parts of her body.
A thorough examination shows hypertension (BP 180/110), truncal obesity with a buffalo hump, and moon face, along with hirsutism and pigmentation, with purple abdominal and lower leg striae. Lab reports confirm the most likely diagnosis.
Question
Based on the most likely diagnosis, high serum levels of what substance are causing hyperpigmentation?
A. Adrenocorticotropic hormone
B. Androgens
C. Cortisol
D. Luteinizing hormone
E. Follicle-stimulating hormone
Adrenocorticotropic Hormone
Hyperpigmentation in Cushing syndrome is due to high serum levels of adrenocorticotropic hormone. Cortisol levels are also increased but not the cause of skin hyperpigmentation.
Case
A 13-year-old girl presents 2 weeks after an upper respiratory infection with diarrhea, sweating, and increased heart rate. Physical examination reveals a tremor and a swollen, tender, painful thyroid gland. Pulse rate is 110/min and blood pressure is 130/60 mm Hg.
LABS
Serum T4: increased
Serum T3: increased
T3 resin uptake: increased
TSH: decreased
Radioactive iodine uptake: very low
Question
What is the appropriate treatment?
A. Naproxen
B. L-Thyroxin sodium
C. Thyroidectomy
D. Methimazole
E. Propylthiouracil
Naproxen
Acute thyroiditis is treated with NSAIDs or beta-blockers. Typical treatment of hyperthyroid are unessessary (thyroidectomy, propylthiouracil, and methimazole)
Case
A 21-year-old woman presents with urinary frequency. Her BMI is 41. A urinalysis is positive for glucose. Her random blood sugar is 257 mg/dL, hemoglobin A1c is 8.5%, and C-peptide is 1.5 ng/mL. She is diagnosed with type 2 diabetes; diet and exercise are recommended. What is the drug of choice for managing her diabetes?
Metformin
A 22-year-old woman presents with an 8-month history of amenorrhea. The patient is also experiencing backaches, headaches, and acne. Physical examination reveals a female patient with a moon-shaped facies, multiple purple striae, and significant central obesity (body mass index of 36).
What is the most likely diagnosis?
Cushings Syndrome
A 35-year-old woman presents with a history of weight gain, fatigue, and hypertension. She has a rounded face, a buffalo hump, and purple striae on her abdomen. Laboratory tests reveal an elevated 24-hour urinary free cortisol level. What is the next best step in confirming the diagnosis of Cushing’s syndrome?
A. Measurement of serum ACTH levels
B. High-dose dexamethasone suppression test
C. Low-dose dexamethasone suppression test
D. Repeat 24-hour urinary free cortisol measurement
Low-dose dexamethasone suppression test
While the 24-hour urinary free cortisol test is specific and used to diagnose Cushing’s syndrome, the low-dose dexamethasone suppression test is often used as a next step to confirm the diagnosis and help differentiate between Cushing’s syndrome and other causes of hypercortisolism.
A patient is diagnosed with Cushing’s disease. What is the most likely cause of this condition?
A. Ectopic ACTH production
B. Adrenal adenoma
C. Pituitary adenoma
D. Exogenous glucocorticoid use
Pituitary adenoma
Which of the following findings would you expect in a patient with Cushing’s disease as opposed to ectopic ACTH syndrome?
A. Elevated plasma ACTH levels
B. Suppression of cortisol with high-dose dexamethasone
C. Hyperpigmentation
D. Presence of an adrenal mass on imaging
Suppression of cortisol with high-dose dexamethasone
The low-dose dexamethasone suppression test is used for screening Cushing’s syndrome and typically does not suppress cortisol in patients with Cushing’s disease. The high-dose dexamethasone suppression test is used to differentiate between Cushing’s disease and ectopic ACTH syndrome, as it can suppress cortisol in Cushing’s disease but not in ectopic ACTH syndrome. This is because the pituitary adenoma retains some sensitivity to glucocorticoid feedback inihibition.
A 45-year-old man presents with signs and symptoms suggestive of Cushing’s syndrome. His serum ACTH levels are low, and a CT scan reveals a unilateral adrenal mass. What is the most likely diagnosis?
A. Cushing’s disease
B. Ectopic ACTH syndrome
C. Adrenal carcinoma
D. Pituitary adenoma
Adrenal Carcinoma
An adrenal carcinoma is a primary adrenal tumor that produces cortisol independently of ACTH, leading to suppressed ACTH levels due to negative feedback.
After confirming the diagnosis of Cushing’s disease, what is the first-line treatment for this condition?
A. Bilateral adrenalectomy
B. Transsphenoidal resection of the pituitary tumor
C. Medical therapy with ketoconazole
D. Radiation therapy to the pituitary gland
Transsphenoidal resection of the pituitary tumor
A 50-year-old woman presents with weight gain, hypertension, and glucose intolerance. Her 24-hour urinary cortisol level is elevated, and serum ACTH is undetectable. Imaging reveals bilateral adrenal hyperplasia. Which test is most appropriate to identify the cause of her condition?
A. Inferior petrosal sinus sampling
B. Low-dose dexamethasone suppression test
C. High-dose dexamethasone suppression test
D. MRI of the pituitary gland
High-dose dexamethasone suppression test
The high-dose dexamethasone suppression test can help differentiate between different causes of Cushing’s syndrome. Since the patient’s serum ACTH is undetectable and she has bilateral adrenal hyperplasia, the most likely diagnoses are an ACTH-independent cause of Cushing’s syndrome such as primary adrenal hyperplasia or adrenal adenomas. However, it can also help rule out ectopic ACTH syndrome if there is any suspicion.
Which of the following is a potential long-term complication of untreated Cushing’s disease?
A. Adrenal insufficiency
B. Osteoporosis
C. Hypoglycemia
D. Hyperkalemia
Osteoporosis
Chronic exposure to high levels of cortisol in untreated Cushing’s disease leads to increased bone resorption and decreased bone formation, resulting in osteoporosis.
A 28-year-old woman presents with clinical features of Cushing’s syndrome. Her serum cortisol levels are elevated, and a low-dose dexamethasone suppression test fails to suppress cortisol levels. Serum ACTH levels are also elevated. What is the next best step to differentiate between pituitary and ectopic sources of ACTH?
A. High-dose dexamethasone suppression test
B. Inferior petrosal sinus sampling
C. CT scan of the chest and abdomen
D. Serum cortisol measurement after metyrapone administration
Inferior petrosal sinus sampling
Inferior petrosal sinus sampling is the most specific and definitive test to differentiate between pituitary (Cushing’s disease) and ectopic sources of ACTH production in patients with Cushing’s syndrome. This test directly measures the gradient of ACTH between the pituitary drainage and peripheral blood, providing clear evidence of the source of excess ACTH.
In the differential diagnosis of Cushing’s syndrome, which of the following is a distinguishing feature of exogenous glucocorticoid use?
A. Elevated serum ACTH levels
B. Bilateral adrenal hyperplasia
C. Suppressed serum ACTH levels
D. Presence of a pituitary adenoma on MRI
Suppressed serum ACTH levels
Exogenous glucocorticoid use leads to suppression of the hypothalamic-pituitary-adrenal axis, resulting in low or undetectable ACTH levels. This is because the exogenous glucocorticoids provide negative feedback to the pituitary and hypothalamus, reducing the endogenous production of ACTH.
The distinguishing feature of exogenous glucocorticoid use in the differential diagnosis of Cushing’s syndrome is the suppression of serum ACTH levels. This is due to the negative feedback exerted by the exogenous glucocorticoids on the hypothalamic-pituitary-adrenal axis, leading to decreased production of ACTH. This feature helps differentiate exogenous glucocorticoid use from other causes of Cushing’s syndrome, which typically involve elevated or normal ACTH levels.
A patient with known Cushing’s disease undergoes transsphenoidal surgery for resection of a pituitary adenoma. Postoperatively, what is the most important immediate complication to monitor for?
A. Hyperglycemia
B. Hypertension
C. Adrenal insufficiency
D. Osteoporosis
What would the treatment be for this complication?
Adrenal Insufficiency
Replacement of corticosteroid
The most important immediate complication to monitor for in a patient who has undergone transsphenoidal surgery for resection of a pituitary adenoma causing Cushing’s disease is adrenal insufficiency. This condition can arise acutely because the body’s own cortisol production may be suppressed following the removal of the source of excess ACTH. Adrenal insufficiency requires prompt diagnosis and treatment with corticosteroid replacement to prevent severe complications.
