A 13-year-old boy is evaluated for abnormal growth.  His mother says that he has grown rapidly over the past 10 months and is much taller than his older brother and other children his age.  During this time, she has had a hard time finding clothes that fit him and has had to buy new shoes for him each month due to increasing foot size.  The patient says that he feels well except for excessive sweating.  He has no history of major medical illness and takes no medications.  Both parents are of average height and have normally proportioned limbs.  The patient is above the 99th percentile for height and at the 90th percentile for weight.  On physical examination, he has long extremities with large hands and feet; the lower jaw is protruding.  Heart sounds are normal.  Sexual development is Tanner stage 4.  Which of the following is the most likely underlying cause of this patient’s condition?

A 45-year-old woman calls 911 due to severe chest pain and dyspnea.  The emergency medical team finds the patient unresponsive with no pulse, and she does not revive despite extensive cardiopulmonary resuscitation efforts.  She had a prolonged history of systemic lupus erythematosus treated with multiple medications and was recently evaluated for progressive muscle weakness.  Records from the patient’s most recent office visit show an elevated blood pressure and examination findings of facial plethora, truncal obesity, and skin ecchymoses.  She was also found to have mild hyperglycemia.  Medical history included a left hip replacement for osteonecrosis of the femoral head 1 year ago.  At autopsy, she is found to have an occluding thrombus in the left main coronary artery, which likely led to sudden cardiac death.  Examination of this patient’s adrenal glands is most likely to reveal which of the following findings?

A 55-year-old woman comes to the office due to increasing fatigability and a 4.54-kg (10-lb) weight gain over the last few months.  The patient used to swim daily but now does so only once or twice a week due to fatigue.  She takes a daily multivitamin and an over-the-counter medication for constipation.  Blood pressure is 140/96 mm Hg and pulse is 55/min.  Physical examination shows hair loss involving the lateral third of the eyebrows.  There is delayed relaxation of the deep tendon reflexes of the knee and ankle.  Which of the following laboratory tests is the most appropriate next step in evaluation of this patient’s symptoms?

A 43-year-old woman comes to the office to discuss amenorrhea.  She began having irregular menses 2 years ago, and her last menstrual period was 9 months ago.  Family history is unremarkable.  Laboratory studies show an increased serum prolactin level, a normal TSH level, and an undetectable β-hCG concentration.  Serum calcium is normal.  MRI reveals a 6-mm pituitary adenoma.  The patient refuses medical and surgical therapy as she is happy about not having menstrual periods.  If left untreated, this patient is at greatest risk of developing which of the following?

A 43-year-old man comes to the emergency department due to painful muscle cramps.  He also has had a tingling sensation around his mouth since earlier in the day and an intermittent sensation of choking in the throat.  The patient reports a history of “high blood pressure and a thyroid disorder.”  On physical examination, he appears comfortable but anxious.  Heart and lung sounds are normal.  Light tapping anterior to the ear elicits twitching of the perioral muscles.  Further discussion with this patient is most likely to reveal which of the following?

A 32-year-old man comes to the office due to vision problems.  Over the last 6 weeks, he has had several “near-misses” while driving, having been nearly hit by cars coming from both the right and left sides.  He also reports frequent headaches.  The patient has no prior medical conditions and takes no medications.  He does not use tobacco, alcohol, or illicit drugs.  Physical examination reveals deficits in the bilateral temporal visual fields.  Extraocular movements are bilaterally intact, and the remainder of the neurological examination shows no abnormalities.  Which of the following additional findings is most likely to be present in this patient?

A 20-year-old woman is brought to the emergency department due to intractable vomiting and abdominal pain.  She has a several-week history of anorexia and weight loss.  The patient has well-controlled primary hypothyroidism treated with levothyroxine but has not taken her medication for 2 days because of vomiting.  Temperature is 37.6 C (99.7 F), blood pressure is 80/40 mm Hg, pulse is 120/min, and respirations are 18/min.  On physical examination, she is mildly lethargic but oriented.  Generalized hyperpigmentation is present and is most conspicuous over the face, neck, and dorsal surface of the hands.  Urinalysis and chest x-ray are within normal limits.  Finger-stick blood glucose is 60 mg/dL.  A 1-L bolus of normal saline is rapidly infused, and high-flow intravenous fluids are continued.  This patient also requires immediate treatment with which of the following medications?

A 1-week-old boy is brought to the emergency department due to recurrent vomiting and poor feeding.  The infant was born at term via spontaneous vaginal delivery with no complications.  Temperature is 36.7 C (98 F), blood pressure is 58/30 mm Hg, pulse is 180/min, and respirations are 40/min.  On examination, the patient is tired appearing with a sunken anterior fontanelle and dry mucous membranes.  The remainder of the examination is unremarkable.  Laboratory results are as follows:

Which of the following additional laboratory findings are most likely to be seen in this patient?

A 34-year-old man comes to the office due to a 6-month history of progressively worsening headaches.  He has also noticed blurring of his peripheral vision while driving.  The patient has no history of head injuries and has had no associated dizziness, weight change, diplopia, or polyuria.  Medical history is unremarkable, and he takes no medications.  He does not use tobacco, alcohol, or illicit drugs.  Physical examination shows a bitemporal visual field deficit.  Laboratory studies show a serum prolactin level >20 times the upper limit of normal.  Cranial imaging reveals a large pituitary mass.  Which of the following changes in serum GnRH, LH, and testosterone are most likely to be found in this patient?

A 40-year-old woman is hospitalized due to a femoral neck fracture that occurred when she slipped while stepping out of the bathtub.  The patient was diagnosed with a prolactinoma 3 years ago during evaluation of amenorrhea, but she refused medical or surgical treatments.  The tumor is being monitored closely and has not increased in size or caused any visual symptoms.  The patient has no other medical problems, takes no medications, and does not use tobacco, alcohol, or illicit drugs.  She has 3 healthy children and no significant family history.  The underlying mechanism for this patient’s susceptibility to fracture is most likely to cause which of the following additional manifestations?

A 21-year-old man comes to the office due to recent weight loss and fatigue.  The patient is a college athlete and states, “My coach wants me to put on more weight, but I can’t seem to do it.  It doesn’t matter how much I eat, I keep losing weight.  I’ve been really thirsty and drinking lots of water lately too, and it’s causing me to use the bathroom frequently during practice.  I’m worried that I’m going to get dropped from the team if I don’t get myself together.”  He is sexually active and has 1 lifetime partner.  The patient’s father was diagnosed with colon cancer at age 64.  Which of the following studies would be the best next step to establish the diagnosis in this patient?

A 34-year-old woman comes to the office with progressive weight gain over the past year.  She also has weakness, easy bruising, and irregular menstrual periods.  The patient takes no medications and has no drug allergies.  Blood pressure is 150/90 mm Hg and pulse is 78/min.  Laboratory studies reveal an elevated serum cortisol level that is not suppressed following administration of low-dose dexamethasone.  Her 24-hour urine free-cortisol concentration and plasma ACTH are elevated.  Which of the following histopathologic findings are most likely to be present in this patient’s adrenal glands?

A 34-year-old woman experiences nausea, abdominal pain, and dizziness after undergoing open reduction and internal fixation of a femur fracture.  One year ago, she was diagnosed with systemic lupus erythematosus with significant renal involvement, and she has since been on chronic glucocorticoid therapy with prednisone.  The patient was maintained on her usual daily dose of prednisone throughout the perioperative period.  Blood pressure is 90/60 mm Hg and pulse is 120/min.  Compared to the normal physiologic response to surgery, this patient most likely has which of the following patterns of hypothalamic-pituitary-adrenal axis activity?

A 29-year-old man comes to the office due to progressive headaches, fatigue, and visual disturbances for the past 6 weeks.  He was diagnosed with sarcoidosis a year ago after having a dry cough and hypercalcemia.  The patient’s condition was treated with oral glucocorticoid therapy, which was discontinued after 6 months due to improvement in symptoms.  Physical examination reveals bitemporal defects on visual field testing but is otherwise normal.  Laboratory studies again show mild hypercalcemia, but the remainder of the values, including complete blood count, serum glucose, creatinine, and electrolytes, are within normal reference ranges.  MRI of the brain reveals a soft tissue mass involving the hypothalamus and pituitary stalk.  Which of the following pituitary hormones is most likely elevated in this patient?

A 34-year-old man comes to the clinic due to headaches and mild confusion over the past week.  The patient has a seizure disorder and recently began taking carbamazepine.  Vital signs are within normal limits.  Physical examination shows no abnormalities.  Laboratory studies reveal decreased serum sodium concentration.  The patient is diagnosed with a condition caused by increased release of a hormone that is co-secreted with neurophysins.  This hormone is most likely secreted into the systemic circulation at which of the following sites?

A 25-year-old woman comes to the office due to excessive facial hair growth that has worsened over the past several years.  The patient is very concerned and says it makes her feel self-conscious in public.  She has tried several cosmetic measures, including laser removal and waxing, but the results have been unsatisfactory.  Her past medical history is insignificant, and she takes no medications.  The patient’s last menstrual period was 6 weeks ago, but she regularly has long cycles and otherwise feels well.  She is sexually active with her boyfriend and uses condoms for contraception.  Examination shows moderate obesity with mild hirsutism on the face and chest.  The patient is initiated on a combination oral contraceptive.  Which of the following describes the primary mechanism by which this agent reduces hirsutism?

A 50-year-old female presents with abdominal pain, diarrhea, and weight loss.  She was diagnosed with diabetes mellitus two months ago.  Her serum somatostatin level is highly elevated.  Further evaluation reveals biliary stones.  Suppression of which of the following hormones is most likely responsible for biliary stones?

A 60-year-old man is brought to the emergency department due to altered mental status.  His wife says that he had a nagging cough that seemed to worsen over the past several months and that he began experiencing occasional dizziness earlier this week.  Over the last couple of days, the patient has become increasingly confused, and today he “does not make any sense at all.”  He has no significant past medical history but has smoked a pack of cigarettes daily for the last 40 years.  On physical examination, the patient is incoherent but has an otherwise normal neurologic examination.

Laboratory results are as follows:

Chest x-ray reveals a mass in the right lung.  Which of the following additional findings is most likely to be present in this patient?

A 46-year-old woman is hospitalized for recurrent renal colic.  She has passed 2 urinary stones during the last 2 years.  The most recent stone contained 80% calcium phosphate and 20% calcium oxalate.  The patient also has diffuse aches and pains and has a history of peptic ulcer disease, for which she takes famotidine daily.  Laboratory results are as follows:

Which of the following changes in bone structure is most likely associated with this patient’s condition?

A 48-year-old woman comes to the office for follow-up of primary hypothyroidism due to chronic autoimmune (Hashimoto) thyroiditis.  She feels well and has no palpitations, heat/cold intolerance, diarrhea/constipation, or changes in weight.  The patient takes levothyroxine daily on an empty stomach.  She has no other medical conditions and takes no other medications.  The patient has no drug allergies and does not use tobacco, alcohol, or illicit drugs.  Blood pressure is 120/70 mm Hg and pulse is 72/min.  BMI is 27 kg/m².  On physical examination, the thyroid is normal to palpation.  There is no peripheral edema.  Laboratory results show a serum TSH level of <0.01 µU/mL.  Maintaining the current dose of levothyroxine would put this patient at the greatest risk for which of the following complications?

A 34-year-old man comes to the clinic due to frequent clumsiness.  For the last 6 months, he has had repeated minor injuries from walking into doorways and stationary objects.  The patient was also reprimanded at work for causing his supervisor to spill coffee when he bumped into her in the hallway.  Medical history is notable for recurrent renal stones; following a subsequent diagnostic evaluation, the patient underwent definitive treatment with neck surgery 3 years ago.  Family history is unavailable as the patient was adopted.  Physical examination reveals bitemporal visual field defects.  Cranial nerves, motor strength, and deep-tendon reflexes are otherwise normal.  In addition to brain imaging, this patient should also be screened for which of the following tumors?

A 40-year-old woman is evaluated for intermittent headaches, insomnia, diaphoresis, and unintentional weight loss over the past several months.  The patient has no other medical problems and takes no medications.  She does not use tobacco, alcohol, or illicit drugs and has no significant family history.  The patient is found to have a neoplastic mass producing excessive amounts of hormones that are causing her symptoms.  Surgical resection of the abnormal tissue is performed with no operative complications.  Microscopic examination of the tumor cells shows electron-dense, membrane-bound secretory granules.  Immunohistochemistry is positive for synaptophysin, chromogranin, and neuron-specific enolase.  The abnormal tissue most likely originated from which of the following?

A 56-year-old woman comes to the office due to progressive weight gain and fatigue over the last 4 months.  She also has had increasing difficulty in lifting heavy objects and climbing stairs.  The patient has moderate, persistent bronchial asthma for which she uses inhaled corticosteroids and beta-2 agonists.  Family history is significant for colon cancer in her father.  Blood pressure is 160/90 mm Hg and pulse is 80/min.  On physical examination, there is symmetric proximal muscle weakness of the upper and lower extremities.  Fasting plasma glucose level is 135 mg/dL and 24-hour urinary cortisol is increased.  Further evaluation reveals that high-dose, but not low-dose, dexamethasone suppresses serum cortisol levels.  Serum ACTH levels are high-normal.  Which of the following is the most likely cause of this patient’s symptoms?

A 27-year-old man comes to the office due to recurrent episodes of muscle weakness.  He has no other significant past medical history.  The patient’s weight has been stable for the past few years, and his current BMI is 23 kg/m².  His blood pressure is 190/110 mm Hg supine and 195/110 mm Hg standing.  His heart rate is 70/min supine and 72/min standing.  The rest of the physical examination is unremarkable.  Laboratory evaluation shows very low plasma renin activity.  Overactivity of which of the following structures is most likely responsible for this patient’s symptoms?