Chapter 50: Steroid and Thyroid Hormones
A 45-year-old woman was being regularly reviewed in primary and secondary care because of a 5-year history of type 2 diabetes that had required early insulin treatment, refractory hypertension, and subsequent chronic kidney disease. She had previously described other symptoms, including weight gain, bruising, flushes, and low mood, all of which had been attributed to obesity and menopause. She was not taking any glucocorticoids. After presenting to her local emergency department with a Colles' fracture after a low impact fall, she was referred to the endocrinology department for suspected Cushing syndrome. Analysis for which of the following would be most useful in confirming the initial diagnosis?
A. decreased plasma levels of thyroid-stimulating hormone
B. increased levels of plasma ACTH
D. reduced free plasma testosterone
E. reduced urine cortisol
Answer B: The primary symptoms of Cushing syndrome result from the tissues being exposed to high levels of cortisol for too long. The most common cause of Cushing syndrome is a pituitary adenoma that secretes excess amounts of ACTH. ACTH stimulates the adrenal cortex to synthesize the glucocorticoids, primarily cortisol. Therefore, measurement of elevated plasma ACTH levels can indicate Cushing syndrome. Because ACTH induces cortisol production one would expect to see elevated urinary cortisol in addition to the elevated plasma ACTH.
A 27-year-old woman presented to the ER complaining of nausea and vomiting for 1 week. She also reported 8 months of progressively worsening fatigue. The patient was previously very active as a ballet student, but for the past 8 months she stopped participating in ballet because of lack of energy and poor concentration. One week prior to admission, she developed nausea and had several episodes of vomiting which provoked her visit to the ER. She also reported a poor appetite for months and had lost 10 lb. Physical examination showed dryness and darkening of the skin in several areas. She repeatedly denied purposefully restricting food intake or binging and purging behaviors. There was no abdominal pain, diarrhea, fevers, dysuria, or headache. As the attending physician you suspect this patient is exhibiting signs of Addison disease. Testing for which of the following would be most useful in your diagnosis?
A. decreased plasma estrogen
B. decreased urinary cortisol
D. increased plasma aldosterone
E. increased plasma cortisol
Answer B: Addison disease is characterized by general malaise and debility, irritability of the ...