A 26-year-old woman comes to the office due to excessive fatigue and decreased exercise capacity for the past several weeks.  She delivered a healthy boy 5 months ago with no complications and has been attributing her symptoms to “baby blues.”  The patient enjoys spending time with her son and is excited to return to work.  She has had no change in appetite but has been gaining weight.  The patient has had no insomnia, excessive urination, feelings of worthlessness, or suicidal ideations.  She takes no medications and does not use alcohol, tobacco, or illicit drugs.  Temperature is 36.5 C (97.7 F), blood pressure is 136/92 mm Hg, and pulse is 64/min.  Weight is 70 kg (154 lb) and BMI is 27 kg/m².  Physical examination shows moist mucous membranes and no scleral icterus, lymphadenopathy, or jugular venous distension.  The lungs are clear on auscultation and heart sounds are normal.  The abdomen is soft and nontender.  There is mild, nonpitting edema of the hands and feet.  Laboratory results are as follows:

Which of the following is the definitive treatment for this patient’s hyponatremia?

A 22-year-old man comes to the office to discuss laboratory test results.  He is a competitive cross-country skier and is required to have periodic blood testing to comply with international rules.  The patient feels well except for occasional heartburn for which he takes antacids.  He trains strenuously on a regular basis and is on a very high protein diet.  The patient’s medical history is unremarkable except for a concussion at age 17; at that time, his serum calcium was noted to be borderline high, but the patient did not follow up with his physician after discharge from the hospital.  His father was also found to have hypercalcemia at a young age but has not required any specific treatment and is otherwise healthy.  The patient takes no prescription medications and does not use tobacco, alcohol, or illicit drugs.  Laboratory results are as follows:

Which of the following clinical findings is most likely present in this patient?

A 62-year-old man comes to the emergency department due to worsening chest pain and dyspnea for the past several hours.  Medical history is significant for hypertension, type 2 diabetes mellitus, and gout.  Physical examination shows no abnormalities.  ECG shows nonspecific T-wave changes without ST-segment elevation.  Serum troponin I level is elevated.  Treatment with aspirin, ticagrelor, metoprolol, and low-molecular-weight heparin is initiated.  Coronary angiography performed several hours later reveals stenoses of the mid to distal right coronary artery and the obtuse marginal branch of the left circumflex artery.  Drug-eluting stenting of both lesions is performed, with good postprocedure flow.  Left ventriculography reveals normal systolic function.  A day later, the patient has an elevated serum creatinine level.  He has had no hypotension and urine output is normal.  Physical examination shows moist mucous membranes, normal jugular venous pressure, clear lungs, and normal heart sounds.  There is no rash or extremity edema.  Laboratory results are as follows:

Fractional excretion of sodium (FeNa) is <1%.

Item 1 of 2

Which of the following is the most likely cause of this patient’s renal dysfunction?

Item 2 of 2
If only supportive care is provided, which of the following is the most likely outcome of this patient’s current renal condition?

An elderly male is brought to the emergency department by the police when he was found wandering on the street in the night.  He is confused, disoriented, and intermittently complaining of generalized abdominal pain and thirst.  Any further history is unobtainable.  His blood pressure is 110/80 mmHg, pulse is 98/min, temperature is 36.7C (98 F) and respirations are 22/min.  There is no abdominal rigidity or rebound tenderness.  Laboratory examination shows that his urine is positive for ketones.  His plasma glucose level is 167 mg/dL.  Other laboratory results are pending.

Item 1 of 2

What is the most likely cause of this patient’s condition?

Item 2 of 2

What is the best next step in the management of this patient?

A 74-year-old woman comes to the emergency department because of an episode of syncope.  She has generalized weakness, fever, nausea, dysuria, and urinary frequency.  She has a 3-day history of decreased oral intake.  She lives alone at home.  She does not use tobacco, alcohol, or drugs.  Her medications include aspirin, lisinopril, and ibuprofen.  Her blood pressure is 102/45 mm Hg and pulse is 48/min.  Examination shows dry mucus membranes.  The abdomen is mildly tender, soft, and non-distended.  Cardiac and lung exam show no abnormalities.  The lab studies show:

An ECG shows a rate of 48/min, a regular rhythm, wide QRS complexes, and absent P waves.  Which of the following is the most appropriate next step in management?

A 48-year-old man is brought to the emergency department from a group home due to fever, cough, and lethargy.  The group home supervisor says that the patient has had a productive cough for the past several days and since yesterday has become progressively lethargic.  The patient has a history of hypertension and bipolar disorder.  He takes amlodipine and valproic acid.  He does not use tobacco, alcohol, or illicit drugs.  Temperature is 38.3 C (101 F), blood pressure is 118/72 mm Hg, pulse is 102/min, and respirations are 20/min.  Pulse oximetry shows 96% on ambient air.  The patient is somnolent but awakens to touch and follows instructions.  He has decreased breath sounds and crackles in the right lower hemithorax.  Cardiac examination is normal with the exception of tachycardia.  There is no extremity edema.  Leukocytes are 17,200/mm³ and chest radiography shows right lower lobe opacity with air bronchograms.  Other laboratory results are as follows:

Which of the following is the most likely cause of this patient’s observed electrolyte abnormalities?

A 34-year-old man comes to the emergency department due to 2 weeks of abdominal discomfort, nausea, and vomiting.  Over the last 2 days, he has not been able “to keep anything down.”  The patient is experiencing homelessness.  He has a history of alcohol use disorder and he has been admitted previously for acute pancreatitis, alcohol-related seizures, and aspiration pneumonia.  Blood pressure is 112/78 mm Hg while supine and 94/57 mm Hg while standing.  His pulse is 121/min, regular.  BMI is 16 kg/m².  He looks disheveled and his mucous membranes are dry.  There is mild epigastric tenderness.  Initial laboratory values are the following:

He is treated with intravenous fluids, dextrose and thiamine solution, and folic acid supplementation.  On the second day of hospitalization, he develops severe weakness, saying “I can barely raise my arms!”  Which of the following most likely accounts for his current symptoms?

A 60-year-old man comes to the emergency department due to severe abdominal pain and an inability to void urine for the past 18 hours.  The patient has a year-long history of urinary hesitancy and a weak urinary stream but has always been able to urinate prior to today.  He has not had fever, chills, dysuria, or recent genitourinary trauma or procedures.  The patient also has a history of chronic arthritis of the lumbar spine and was recently prescribed baclofen, which has provided some pain relief.  He does not use tobacco, alcohol, or illicit drugs.  Temperature is 36.5 C (97.7 F), blood pressure is 145/90 mm Hg, pulse is 95/min, and respirations are 18/min.  The patient appears restless and in moderate distress.  Abdominal examination reveals suprapubic fullness and moderate tenderness to palpation with no guarding or rebound tenderness.  An enlarged, smooth, nontender prostate is palpated by digital rectal examination; no masses or fecal impaction are present.  There is no tenderness to palpation of the lower back.  Abbreviated testing of strength and sensory function is normal.  Laboratory results are as follows:

What is the best next step in management of this patient?

A 77-year-old man is brought to the physician by his daughter with a 1-week history of gross hematuria.  He has no frequency, urgency, hesitancy, or dribbling.  His other medical problems include hypertension, chronic low back pain, and chronic renal insufficiency.  The patient’s medications include amlodipine, hydrochlorothiazide, and acetaminophen with codeine as needed.  He has a 46-pack-year smoking history.  Prostate examination shows no abnormalities.  Laboratory results are as follows:

Urine microscopy shows many normal-appearing red cells, but no dysmorphic red cells or casts.  Urine culture shows no growth.  Prostate-specific antigen is 3.2 ng/mL.  Ultrasound of the kidneys shows bilateral cortical atrophy but no other lesions.  Which of the following is the most appropriate next step in management of this patient?

A 66-year-old woman comes to the emergency department due to increasing diarrhea and generalized weakness.  The patient has a history of microscopic colitis and often has 4-6 stools per day.  She has been taking antidiarrheal medications but over the past 3 weeks has experienced worsening diarrhea.  She has increased her fluid intake but feels dehydrated and weak.  The patient has had no fever, abdominal pain, vomiting, or blood in her stool.  Temperature is 37 C (98.6 F), blood pressure is 116/68 mm Hg, pulse is 92/min, and respirations are 12/min.  Physical examination shows a nontender abdomen and decreased skin turgor.  Laboratory results include serum sodium 118 mEq/L and urine sodium 12 mEq/L.  The patient is admitted, and isotonic saline infusion is begun.  She receives 1 L of isotonic saline over 8 hours, and the following changes are observed:

Which of the following is contributing most to this patient’s changes in serum sodium after admission?

A 36-year-old woman with chronic back pain is seen in the emergency department with flank pain radiating to the groin and blood in her urine.  “This pain is killing me,” she says, “and it is quite different from my usual back pain.”  She has been taking ibuprofen and Percocet (oxycodone/acetaminophen) daily for the past 10 years.  She has no fever or dysuria.  Her temperature is 36.7 C (98 F), blood pressure is 152/91 mm Hg, pulse is 100/min, and respirations are 14/min.  Her mucous membranes are moist and pale.  She appears to be in mild distress due to pain.  Examination shows right costovertebral tenderness.  Laboratory results are as follows:

Noncontrast CT of her abdomen and pelvis reveals mild dilation of the right pelvicalyceal system, but no renal calculus is observed.  Serum protein electrophoresis and urine Bence Jones proteins are negative.  What is the most likely cause of her renal dysfunction?

An 18-year-old man comes to the emergency department with flank pain and red urine for the past day.  Approximately 3 days ago, he experienced flu-like symptoms with rhinorrhea and throat pain that improved with over-the-counter acetaminophen.  The patient has no chronic medical conditions and takes no daily medications.  He does not use tobacco, alcohol, or illicit drugs.  Family history is unremarkable.  Temperature is 37.2 C (99 F), blood pressure is 126/76 mm Hg, pulse is 88/min, and respirations are 18/min.  The patient has mild costovertebral tenderness.  The remainder of the physical examination is normal.  Laboratory results are as follows:

Serum complement levels are normal.  Spiral CT scan of the abdomen is normal.  Which of the following is the most likely diagnosis in this patient?

A 32-year-old man comes to the office for a new patient evaluation after relocating for his job.  The patient has a 16-year history of type 1 diabetes mellitus and takes basal plus premeal insulin.  He performs multiple fingerstick blood glucose measurements daily with values ranging from 100 to 300 mg/dL.  His most recent hemoglobin A1c level was 7.9%.  The patient was also diagnosed with early diabetic retinopathy 3 months ago by his ophthalmologist, who recommended close observation.  He does not use tobacco, alcohol, or recreational drugs.  Family history is significant for myocardial infarction in his father.  Blood pressure is 154/92 mm Hg and pulse is 76/min.  Examination shows decreased light touch sensation over the bilateral feet but is otherwise normal.  Laboratory results are as follows:

Estimated glomerular filtration rate (eGFR) is 55 mL/min/1.73 m².  Records from his prior provider show a serum creatinine of 0.8 mg/dL and 1.2 mg/dL a year and 6 months ago, respectively.  Urine testing shows 550 mg/day albuminuria, and a renal biopsy reveals changes suggestive of diabetic nephropathy.  Which of the following would have the greatest impact on limiting the progression of this patient’s kidney disease?

A 24-year-old man is brought into the emergency department after a seizure an hour ago.  The patient’s friend, who witnessed the seizure, says, “We were at a party when he fell to the floor suddenly and started to convulse.  He was acting strange before the seizure.”  The patient’s seizure spontaneously resolved after approximately 2 minutes.  He has no previous history of seizures or medical problems.  Temperature is 37.4 C (99.3 F), blood pressure is 140/90 mm Hg, and pulse is 98/min.  The patient is somnolent but easily arousable and follows instructions.  Bilateral pupils are equal and reactive.  The lungs are clear on auscultation, and heart sounds are normal.  Muscle strength and deep tendon reflexes are normal.  Bilateral plantar reflexes are downgoing.  Laboratory results are as follows:

Electrocardiography shows sinus tachycardia.  Urine toxicology is positive for phencyclidine.  Noncontrast CT scan of the head is normal.  Which of the following is most appropriate to prevent an adverse outcome in this patient?

A 40-year-old man comes to the office for an annual physical examination.  One year ago, routine urinalysis revealed 1+ protein, but the patient was not able to keep his follow-up appointment.  He currently has no symptoms, and his other medical conditions include obesity and nonalcoholic fatty liver disease.  The patient takes no medications.  He does not use tobacco, alcohol, or recreational drugs.  There is no family history of kidney disease.  Blood pressure is 122/70 mm Hg and pulse is 69/min.  BMI is 40.5 kg/m².  Physical examination shows clear lungs, normal heart sounds, no abdominal organomegaly, no extremity edema, and no rashes.  Laboratory results are as follows:

The 24-hour urine protein is 3.2 g/day.  Renal ultrasonography shows normal-sized kidneys.  Primary dysfunction of which of the following renal structures is the most likely cause of this patient’s proteinuria?

A 62-year-old man returns for evaluation of hypertension.  For the past year, his blood pressure has become increasingly difficult to control despite the addition of several antihypertensive medications.  He also has type 2 diabetes mellitus, intermittent claudication, erectile dysfunction, hyperlipidemia, and coronary artery disease.  Currently he takes metoprolol, amlodipine, hydrochlorothiazide, lisinopril, and hydralazine for hypertension.  The patient smokes cigars daily and drinks alcohol socially.  His blood pressure is 165/95 mm Hg, and pulse is 76/min.  On examination, the point of maximal impulse is palpated lateral to the midclavicular line on the left.  Heart sounds are normal.  A bruit is heard on auscultation to the left of the umbilicus.  There is trace pedal edema.  The distal pulses of the lower extremities are diminished bilaterally.  Laboratory results are as follows:

Which of the following is the most appropriate next step in management of this patient?

A 60-year-old man is evaluated for persistent fatigue and generalized weakness.  Medical history is significant for chronic kidney disease and anemia for which he was prescribed darbepoetin therapy 12 weeks ago.  Laboratory results are as follows:

Colonoscopy performed 5 years ago was normal except for mild sigmoid diverticulosis.  Which of the following is the most likely cause of this patient’s persistent anemia?