A 36-year-old woman comes to the office due to weight gain of 9 kg (20 lb) , facial hair growth, easy bruising, and muscle weakness over the last 4 months. She has no other medical problems and takes no medications.
Blood pressure is 148/90 mm Hg and pulse is 80/min. BMI is 31 kg/m². The patient has an unusually round face with deposition of fat in the supraclavicular and posterior neck areas. There is coarse terminal hair on her face and lower abdomen. Skin examination reveals wide striae on the abdomen. There is also mild proximal muscle weakness.
Laboratory results are as follows:
Pregnancy test is negative.
Which of the following is the most appropriate next step in management of this patient?

Question

A 36-year-old woman comes to the office due to weight gain of 9 kg (20 lb) , facial hair growth, easy bruising, and muscle weakness over the last 4 months. She has no other medical problems and takes no medications.
Blood pressure is 148/90 mm Hg and pulse is 80/min. BMI is 31 kg/m². The patient has an unusually round face with deposition of fat in the supraclavicular and posterior neck areas. There is coarse terminal hair on her face and lower abdomen. Skin examination reveals wide striae on the abdomen. There is also mild proximal muscle weakness.
Laboratory results are as follows:

Pregnancy test is negative.
Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

This patient has typical features of Cushing syndrome, including several classic physical examination findings as well as weight gain, hirsutism, and hyperglycemia. The evaluation of patients with suspected Cushing syndrome is a 2-step process: physical examination Step 1. Confirm the diagnosis: Patients must have abnormal results on at least 2 different screening tests (eg, low-dose dexamethasone suppression test, 24-hour urine free cortisol assay, late-night salivary cortisol assay), as seen in this patient.Step 2. Establish the etiology: Once the initial diagnosis is confirmed, it is necessary to differentiate ACTH-independent (low ACTH) and ACTH-dependent (normal or high ACTH) Cushing syndrome by measuring a plasma ACTH level. This is the best next step in the evaluation of this patient. Step 1. Confirm the diagnosis: Patients must have abnormal results on at least 2 different screening tests (eg, low-dose dexamethasone suppression test, 24-hour urine free cortisol assay, late-night salivary cortisol assay), as seen in this patient. Step 1. Confirm the diagnosis: Patients must have abnormal results on at least 2 different screening tests (eg, low-dose dexamethasone suppression test, 24-hour urine free cortisol assay, late-night salivary cortisol assay), as seen in this patient. Step 2. Establish the etiology: Once the initial diagnosis is confirmed, it is necessary to differentiate ACTH-independent (low ACTH) and ACTH-dependent (normal or high ACTH) Cushing syndrome by measuring a plasma ACTH level. This is the best next step in the evaluation of this patient. Step 2. Establish the etiology: Once the initial diagnosis is confirmed, it is necessary to differentiate ACTH-independent (low ACTH) and ACTH-dependent (normal or high ACTH) Cushing syndrome by measuring a plasma ACTH level. This is the best next step in the evaluation of this patient. (Choice B) Patients with ACTH-independent Cushing syndrome (ACTH <5 pg/mL) usually have a cortisol-secreting adrenal mass or adrenal hyperplasia. CT scan of the adrenal glands should be ordered next to look for these conditions. (Choices C, D, and E) The vast majority of patients with ACTH-dependent Cushing syndrome will have an ACTH-secreting pituitary adenoma (ie, Cushing disease) rather than an ectopic ACTH-secreting tumor. Evaluation of these patients varies among centers and may include high-dose dexamethasone suppression tests, corticotropin-releasing hormone stimulation testing, MRI of the pituitary gland, desmopressin stimulation testing, or inferior petrosal sinus sampling. A pituitary adenoma >6 mm on MRI associated with suppression of cortisol following high-dose dexamethasone strongly suggests a corticotroph pituitary adenoma. In contrast, most patients with ectopic ACTH-secreting tumors will have no suppression of cortisol secretion following high-dose dexamethasone administration as theses tumors are completely resistant to feedback inhibition by glucocorticoids. Educational objective: The first step in evaluation of Cushing syndrome is to confirm the diagnosis with a low-dose dexamethasone suppression test, 24-hour urine free cortisol assay, or late-night salivary cortisol assay. Patients must have abnormal results on 2 different tests. ACTH-dependent and ACTH-independent Cushing syndrome should then be differentiated with a plasma ACTH level. __________ References: The diagnosis of Cushing's syndrome: an Endocrine Society Clinical Practice Guideline. (http://www.ncbi.nlm.nih.gov/pubmed/18334580)

A 36-Year-Old Woman Comes to the Office Due to Weight