A 62-year-old hospitalized man is evaluated due to acute renal failure.  The patient was hospitalized 3 days ago due to precordial chest pain.  During admission, he was found to have an elevated troponin I level but no ST-segment elevation on ECG; subsequent percutaneous catheterization with injection of contrast dye revealed 3-vessel coronary artery disease.  The patient has continued to receive medical treatment while awaiting coronary artery bypass graft surgery.  Today, he has elevated blood urea nitrogen and serum creatinine levels.  The patient has had no fever, and blood pressure and heart rate have been within normal limits.  Physical examination shows no new findings.  Which of the following changes are most likely to be present in this patient’s kidneys?

A 15-year-old girl comes to the office for follow-up.  The patient was diagnosed with Wilson disease a year ago, at which time she began penicillamine therapy.  Her dysarthria and academic performance have since improved.  Vital signs are normal.  Laboratory results are as follows:

Which of the following is the most likely explanation for this patient’s laboratory findings?

A 48-year-old woman comes to the emergency department due to worsening headache, blurred vision, and nausea for the past several days.  She also has had decreased urine output.  Medical history is significant for systemic sclerosis.  Blood pressure is 190/110 mm Hg and pulse is 96/min.  Physical examination shows diffuse skin thickening involving the hands, face, and anterior chest.  There are no focal neurologic deficits, but a flame-shaped retinal hemorrhage is present.  Laboratory studies reveal elevated serum blood urea nitrogen and creatinine levels, which were within normal limits during a recent office visit.  Urine microscopy shows no sediment.  A primary injury to which of the following structures is the most likely cause of this patient’s acute kidney injury?

A 55-year-old man comes to the hospital due to progressive fatigue and weakness.  Medical history includes type 2 diabetes mellitus and obesity.  Laboratory results are as follows:

Which of the following is the most likely diagnosis?

A 67-year-old woman is hospitalized due to worsening abdominal pain.  The patient has long-standing end-stage renal disease from diabetic nephropathy for which she undergoes hemodialysis 3 times a week.  Temperature is 37 C (98.6 F), blood pressure is 159/79 mm Hg, pulse is 97/min, and respirations are 16/min.  Abdominal examination shows high-pitched bowel sounds and mild distension without rebound tenderness.  Laboratory results show elevated blood urea nitrogen and creatinine.  Noncontrast CT scan of the abdomen shows a small bowel obstruction.  The patient also has the findings demonstrated by the arrows in the abdominal CT scan below:

Which of the following most likely contributed to the observed findings?

A 56-year-old man with chronic kidney disease is seen for a routine follow-up visit.  The patient also has type 2 diabetes, hypertension, and hyperlipidemia.  His serum creatinine level has been increasing over the past 2 years.  Blood pressure is 144/90 mm Hg and pulse is 88/min.  Weight is 80 kg (176 lb).  Physical examination is normal except for trace pitting ankle edema.  Serum creatinine level is 1.8 mg/dL; 1 year ago, serum creatinine was 1.4 mg/dL.  Serum calcium and phosphorus levels are in the normal range.  Which of the following is most likely responsible for maintaining the serum phosphorus within normal range despite declining renal function?

A 24-year-old man is being evaluated for gross hematuria.  Cystoscopy under general anesthesia is performed.  After the scope is passed into the urinary bladder, a triangular portion of the bladder floor formed by the internal urethral orifice and 2 slit-like openings is observed.  Gross blood is seen oozing from one of the slit-like openings.  Which of the following is the most likely cause of this patient’s hematuria?

A 32-year-old woman comes to the office due to a 2-day history of worsening headache and double vision.  The patient reports no chronic medical conditions but has had nasal discharge for the past several days.  Physical examination shows weakness of the muscle shown on the below CT scan:

Purulent discharge from the sphenoethmoidal recess of the nasal cavity is also noted.  Involvement of which of the following nerves best explains this patient’s ocular findings?

A 20-year-old man is brought to the emergency department after a motor vehicle collision.  Blood pressure is 130/84 mm Hg, pulse is 108/min, and respirations are 18/min.  The airway is intact, and breath and heart sounds are normal.  There is bruising across the central lower abdomen and the suprapubic area is tender to palpation.  Chest x-ray and pelvic x-ray reveal no fractures.  Bedside ultrasound shows intraperitoneal free fluid.  Urine dipstick test is positive for blood.  CT scan of the abdomen and pelvis is most likely to reveal which of the following injuries in this patient?

A 64-year-old woman is evaluated for episodic urinary incontinence.  Urodynamic studies reveal an overactive bladder.  Symptoms persist after behavioral interventions, and the patient is unable to tolerate medical treatment.  Low-amplitude electrical stimulation therapy that helps modulate neural control of the urinary bladder muscle, urethral sphincter, and pelvic muscles is planned.  A stimulating electrode is most likely to be placed close to which of the following structures during this procedure?

A 70-year-old man is brought to the emergency department an hour after sudden-onset, right-sided weakness and double vision.  Medical history is significant for type 2 diabetes mellitus, hypertension, and hyperlipidemia.  Blood pressure is 160/102 mm Hg and pulse is 82/min.  The patient is alert, oriented, and able to follow commands.  Speech is normal.  On examination, the left eye has ptosis and is fixed in the outer position, and the pupil is dilated.  The right eye, the right pupil, and right eye movements are normal.  Muscle strength is normal in the left upper and lower extremities and is 3/5 in the right.  Deep tendon reflexes are 3+ on the right and 2+ on the left.  Babinski sign is present on the right and absent on the left.  There is no ataxia.  Sensation is intact.  Which of the following is the most likely location of this patient’s lesion?

A 46-year-old woman is admitted for elective hysterectomy due to abnormal uterine bleeding.  The patient has a history of diabetes mellitus and urinary incontinence, and she smoked cigarettes occasionally for years before quitting 5 years ago.  She is prepared for surgery, and an indwelling urinary catheter is placed.  The surgery is completed without complications and the patient is transferred to the hospital ward for recovery.  The indwelling catheter is kept in place for the next 72 hours. The patient subsequently develops a fever of 39 C (102.2 F), along with suprapubic and costovertebral angle tenderness.  Urine culture shows >10⁵ colony-forming units/mL of extended-spectrum, beta-lactamase–producing Escherichia coli.  Which of the following is the most important risk factor for this patient’s infection?