A 38-year-old man is brought to the emergency department due to progressive nausea, confusion, and unsteady gait.  Family members state that symptoms started 4 days ago after he went to the dentist due to a toothache, for which he was prescribed ibuprofen.  He also takes lithium for bipolar disorder.  On examination, he is drowsy and ataxic, having slurred speech and coarse tremors.  His serum lithium level is 3.86 mEq/L (therapeutic range: 0.8-1.2 mEq/L), and serum creatinine and blood urea nitrogen are elevated.  While in the emergency department, he develops a generalized tonic-clonic seizure.  During emergent hemodialysis treatment, his blood is passed along a semipermeable membrane and allowed to equilibrate with a dialysate solution.  Which of the following is most likely to increase the rate of drug removal?

A 24-year-old woman comes to the office for a routine prenatal ultrasound examination.  She is 19 weeks pregnant based on her last menstrual period.  This is the patient’s third pregnancy, and there have been no complications.  Family medical history is unremarkable, and both of the patient’s children are healthy.  The examination reveals a male fetus with bilaterally enlarged kidneys with diffuse small cysts.  The amniotic fluid volume is very low.  No other anomalies are seen.  Which of the following will most likely be present in the newborn at delivery?

A 65-year-old man comes to the office for evaluation of blood in the urine.  The patient has no abdominal pain, urinary frequency, or urgency.  He has hypertension, type 2 diabetes mellitus, and stage II chronic kidney disease.  He quit smoking 10 years ago and had smoked a pack of cigarettes daily for 30 years.  On examination, vital signs are within normal limits.  The patient’s BMI is 33 kg/m².  After appropriate work-up, the patient undergoes a renal biopsy; histopathologic findings are shown below.

Which of the following processes most likely accounts for the abnormal appearance of these cells?

Four children and 2 adults are currently being followed in a nephrology clinic for poststreptococcal glomerulonephritis.  Three patients initially had gross hematuria and edema requiring diuretic administration.  The remaining 3 patients had microscopic hematuria and hypertension.  C3 levels were decreased in all patients, and antistreptolysin O titer was elevated in 4 of them.  None of the patients have preexisting renal disease.  Which of the following patient characteristics is most likely to indicate a poor long-term prognosis?

A 21-year-old woman with type 1 diabetes mellitus comes to the office for a follow-up appointment.  She has been using daily long-acting and short-acting insulin injections from the time she was diagnosed 6 years ago.  The patient was seen by her ophthalmologist 2 weeks ago and had no signs of diabetic retinopathy.  She eats a balanced diet and jogs every morning for 40 minutes.  On examination, the skin of her extremities is intact and peripheral pulses are palpable.  Sensory examination shows normal pinprick, vibration, and temperature sensation in her lower extremities.  Laboratory evaluation shows normal renal function and lipid profile.  The patient’s hemoglobin A1c level is 7%.  Screening for early-stage diabetic nephropathy in this patient would best be accomplished by measuring the urinary concentration of which of the following substances?

A 20-year-old woman comes to the office due to gross hematuria.  She otherwise feels well and has had no recent illnesses.  She had a prior episode of hematuria 2 years ago that resolved spontaneously.  The patient was diagnosed with type 1 diabetes mellitus approximately a year ago and is taking daily insulin injections.  She works in a day care center and does not use tobacco, alcohol, or illicit drugs.  Temperature is 37 C (98.6 F), blood pressure is 120/80 mm Hg, and pulse is 80/min.  Physical examination shows no abnormalities.  Laboratory results are as follows:

Which of the following is the most likely diagnosis?

A 68-year-old woman comes to the office due to increasing low back pain.  The pain is constant and worsens at night.  She has also had a 6.8-kg (15-lb) weight loss over the past 3 months.  Medical history is significant for osteoporosis and hypothyroidism.  Family history is significant for breast cancer in her mother.  She has smoked 1 pack of cigarettes daily for 30 years and drinks 1 or 2 glasses of wine every day.  The patient immigrated to the United States from China 30 years ago; she mainly eats food she cooks herself.  Vital signs are within normal limits.  Physical examination shows point tenderness over the L3 and L4 vertebrae.  MRI reveals lytic bone lesions in the corresponding vertebrae and also a right lower pole kidney mass.  Histologic examination of the mass is shown below:

Which of the following risk factors most likely contributed to this patient’s current condition?

A 47-year-old man is treated for bacterial sinusitis with ampicillin.  A week later he comes to the emergency department with fever and a skin rash.  He also reports low urine output.  Temperature is 37.5 C (99.5 F), blood pressure is 123/71 mm Hg, and pulse is 88/min.  Physical examination shows a diffuse maculopapular rash.  Serum creatinine level is 2.4 mg/dL, and urine sediment microscopy reveals 3-4 red blood cells/hpf, 5-10 white blood cells/hpf, and 3-5 eosinophils/hpf.  The pathologic process affecting this patient’s kidneys most likely involves which of the following structures?

A 32-year-old man is hospitalized with multiple fractures and internal bleeding following a motor vehicle collision.  He is successfully resuscitated and taken to the operating room for fixation of a left femoral fracture.  The patient’s condition remains stable postoperatively, and he is transferred to the surgical floor.  Blood pressure is 118/68 mm Hg and pulse is 88/min.  He develops oliguria on the second day of hospitalization.  Renal biopsy findings are shown in the image below.

If the kidney biopsy were repeated 1 month from now, which of the following would most likely be seen?

A 5-year-old boy is brought to the office by his mother, who notes that her son’s eyes and feet have looked puffy over the last several weeks.  She is unaware of exactly when this began but says the patient had a mild upper respiratory tract infection several weeks ago.  The boy has no pain but mentions that his shoes seem to fit tightly and bother him, especially when he runs outside during recess at school.  The mother also remarks that the boy’s urine has been excessively foamy recently.  On further questioning, the mother states that she has seasonal allergies and asks whether her child also has allergies.  Physical examination is remarkable for periorbital edema and lower extremity edema.  Urinalysis shows 4+ proteinuria but is otherwise unremarkable.  Which of the following secondary changes is most likely in this patient?

A 5-year-old boy is brought to the office with generalized edema that developed following a mild upper respiratory infection.  Medical history is unremarkable.  Blood pressure and heart rate are normal.  Serum creatinine levels are normal.  Urinalysis shows massive proteinuria with no hematuria.  Further analysis reveals that urine protein consists principally of albumin with only trace amounts of IgG and alpha-2-macroglobulin.  Which of the following pathologic changes is the most likely cause of this patient’s urinary protein loss?

A 62-year-old man comes to the office due to poorly localized, intermittent abdominal pain that is triggered by eating and slowly subsides over the ensuing several hours.  The patient has also lost 4.5 kg (10 lb) over the past 2 months.  He has a history of hypertension and hyperlipidemia and has smoked a pack of cigarettes daily for 40 years.  Blood pressure is 175/105 mm Hg and pulse is 70/min and regular.  The abdomen is soft and nontender.  CT scan of the abdomen reveals the renal findings shown in the image below.

This patient most likely suffers from which of the following conditions?

A nephrology researcher conducts a clinical study to determine the risk factors for the development of renal calculi.  He recruits a number of patients with a history of idiopathic calcium oxalate kidney stones, along with age- and sex-matched healthy subjects.  Detailed medical, surgical, and nutritional histories are obtained, and several serum and urine laboratory tests are performed.  Which of the following is most likely to be seen in affected patients compared with healthy individuals?

A 63-year-old man comes to the emergency department due to fever and loss of appetite.  He also has chest pain with deep breaths.  The patient has never had regular medical care and his medical history is unknown.  He has smoked half a pack of cigarettes daily for 30 years.  Laboratory evaluation shows a hematocrit of 56%.  Chest imaging shows multiple round lesions in both lungs.  Biopsy of one of the lesions reveals the microscopic findings shown below.

This patient’s metastatic disease most likely originated from which of the following organs?

A 23-year-old man comes to the office due to 3 weeks of malaise and fatigue.  He says, “I’ve been sick with the flu for the last 3 weeks.  I don’t know why I’m not getting better.”  The patient also has profound fatigue causing difficulty with day-to-day activities.  His temperature is 38.4 C (101.2 F).  Cardiac auscultation reveals an apical holosystolic murmur radiating to the axilla, which was not heard during previous office visits.  Laboratory evaluation shows serum creatinine of 2.3 mg/dL.  Mild proteinuria and microscopic hematuria with red cell casts are present on urinalysis.  Which of the following is the most likely pathogenesis of this patient’s renal findings?

A 57-year-old man comes to the hospital due to nausea, vomiting, and severe crampy pain in the right flank.  He has had no fever or chills.  Several days ago, the patient had similar, but less severe, pain that resolved spontaneously.  Medical history is significant for type 2 diabetes mellitus, obesity, hyperlipidemia, hypertension, and gout.  Temperature is 37 C (98.6 F), blood pressure is 160/100 mm Hg, and pulse is 98/min.  Physical examination shows right flank tenderness.  Blood urea nitrogen and serum creatinine are normal.  Abdominal ultrasound reveals right-sided hydronephrosis and proximal ureteral dilation.  Urinalysis in this patient would most likely reveal which of the following?

A 32-year-old woman comes to the emergency department with sudden-onset left flank pain and nausea.  The pain radiates to the left groin and she is unable to find a comfortable position on the examination table.  The pain is intermittent and waxes and wanes in severity.  Temperature is 36.7 C (98 F), blood pressure is 140/90 mm Hg, and pulse is 92/min.  She has mild tenderness to percussion over the left flank.  Bowel sounds are hypoactive.  Which of the following recommendations would most likely prevent a recurrence of this patient’s condition?

A 64-year-old man comes to the office due to several episodes of intermittent hematuria over the past 2 months.  He has had no abdominal pain, burning on urination, or fever but has lost 4.5 kg (10 lb) since the onset of symptoms.  The patient has smoked a pack of cigarettes daily for 30 years.  Vital signs are within normal limits.  The abdomen is soft, nontender, and nondistended.  An enlarged and firm prostate is palpated on digital rectal examination.  Serum calcium is 12.3 mg/dL.  Urinalysis shows 30-40 red blood cells/hpf, negative protein, and no casts.  A CT scan of the abdomen is shown below.

Which of the following is the most likely diagnosis?

A 42-year-old man comes to the office due to hematuria, fatigue, and nasal congestion for the last few weeks.  He has no chronic medical conditions.  Blood pressure is 160/96 mm Hg.  Physical examination shows edema around the ankles, hands, and face.  Laboratory results reveal blood urea nitrogen of 40 mg/dL and serum creatinine of 3.8 mg/dL.  Urinalysis shows moderate proteinuria and a large amount of red blood cells (RBCs) with RBC casts.  A kidney biopsy is performed.  Light microscopy reveals cellular proliferation, focal necrosis, and crescent formation of most of the glomeruli.  On immunofluorescent microscopy, there are no immunoglobulin or complement deposits.  Which of the following additional findings is most likely to be present in this patient?

A 38-year-old man is brought to the emergency department due to vomiting blood.  After appropriate resuscitation measures, he undergoes upper gastrointestinal endoscopy, which reveals a bleeding duodenal ulcer.  During hospital day 2, the patient develops decreased urine output.  Serum creatinine rises to 3.0 mg/dL from a baseline of 1.2 mg/dL.  Renal biopsy shows patchy epithelial necrosis of the tubules, tubulorrhexis, and intratubular casts.  Supportive care is provided.  Several days later, his urine output significantly increases and serum creatinine levels decline.  Over the next few days, this patient is at highest risk for which of the following complications?

An 8-year-old boy is brought to the office due to acute facial puffiness.  His mother reports that for the preceding 24 hours he has been easily fatigued and has had dark urine.  The patient was treated for a skin infection 3 weeks ago but has no chronic medical conditions.  Temperature is 36.1 C (97 F) and blood pressure is 140/94 mm Hg.  Physical examination shows periorbital edema and mild pitting edema along the ankles.  The remainder of the examination shows no abnormalities.  A representative renal biopsy sample is shown in the image below:

The fluorescent areas on the slide most likely indicate the presence of which of the following substances?

A 43-year-old man comes to the office due to shortness of breath and fatigue.  Over the last 2 weeks, his fatigue has been so profound that he has “little energy, even to get out of bed.”  The patient has no chills but has experienced recent weight gain and ankle swelling.  He has no prior medical conditions and takes no medications.  Blood pressure is 168/94 mm Hg, and pulse is 95/min and regular.  The patient has bilateral lower extremity pitting edema limited to the ankles.  Urinalysis reveals 2+ protein, white blood cell count of 5-7/hpf, and red blood cell count of 75-100/hpf.  He undergoes a kidney biopsy; immunofluorescent microscopy findings are shown in the image below.

Which of the following would be the most likely finding on light microscopy in this patient?

A 32-year-old man comes to the emergency department due to sudden onset of severe right flank pain that radiates toward the groin.  He also has gross hematuria but no fever or dysuria.  The patient has no significant medical conditions and has never experienced similar symptoms.  He takes no medications.  Temperature is 36.7 C (98.1 F), blood pressure is 120/80 mm Hg, and pulse is 88/min.  The right flank is tender to palpation.  There is no costovertebral angle tenderness.  Imaging shows a stone in the middle of the right ureter.  Which of the following is most likely to be seen on laboratory evaluation of this patient?

A 51-year-old man comes to the emergency department with sudden-onset, sharp, left flank pain; nausea; and vomiting.  He has had no dysuria or hematuria.  The patient has no past medical conditions and takes no daily medications.  He does not use tobacco, alcohol, or illicit drugs.  Temperature is normal.  On examination, the patient appears to be in severe pain and cannot find a comfortable position on the bed.  There is no abdominal rigidity or rebound, and no masses are palpable.  Cardiopulmonary examination is normal.  There is no peripheral edema.  Imaging shows a 1-cm calculus in the left proximal ureter at the level of the L3 vertebra; the renal pelvis and proximal ureter are dilated, as shown in the exhibit.  Which of the following is most likely increased in this patient’s left kidney?

Scientists studying the kidney’s response to hypoperfusion apply a clip to a pig’s right renal artery that reduces blood flow to the kidney by about 70%.  After 6 months, they perform a right nephrectomy and examine the glomeruli and tubules microscopically.  Which of the following cell types would be most likely to undergo hyperplasia as a result of the clip placement?

A 9-year-old girl is brought to the office due to 2 days of face and eye puffiness.  The patient was treated for a rash on her leg with an antibiotic about 3 weeks ago.  Temperature is 37.2 C (99 F) and blood pressure is 150/90 mm Hg.  On physical examination, there is generalized edema but no rash.  Urinalysis reveals proteinuria and hematuria.  An electron microscopy image representative of this patient’s disease process is shown below:

The area marked by the arrow most likely represents which of the following?

A 44-year-old man comes to the office for a routine check-up.  Past medical history is significant for hypercholesterolemia, which he has controlled through diet.  His father died of a myocardial infarction at age 56, and his mother, who is still living, has a history of stroke.  On physical examination, the patient’s blood pressure is 160/100 mm Hg and heart rate is 70/min.  He is started on enalapril.  During the first 7 days of therapy, the patient’s glomerular filtration rate (GFR) adjusts as shown in the graph below.

Which of the following structures was most likely affected by a downstream effect of enalapril and is therefore responsible for this patient’s renal response?

A 76-year-old man comes to the hospital due to acute, bright red blood from the rectum.  The patient had 3 large bloody bowel movements this morning, and he has felt light-headed and dizzy since.  He has a history of sigmoid diverticulosis and, 2 years ago, had a similar episode of bleeding that resolved spontaneously.  Temperature is 36.9 C (98.4 F), blood pressure is 90/50 mm Hg, and pulse is 110/min.  Examination shows mild lethargy and delayed capillary refill.  Abdominal examination shows no abnormalities.  Which of the following physiologic changes in kidney function would be most likely in this patient?

A 78-year-old woman is brought to the office by her son for follow-up.  The patient was hospitalized 5 days ago due to fever, vomiting, dysuria, and flank pain.  Acute pyelonephritis was diagnosed, and she was treated with ceftriaxone and given intravenous fluids.  Urine culture grew Escherichia coli, and the patient was discharged home with a prescription for levofloxacin, which she is still taking.  Since hospital discharge, the patient has had nausea and loss of appetite, but her fever and urinary symptoms have resolved.  Temperature is 36.4 C (97.5 F), blood pressure is 116/68 mm Hg, and pulse is 92/min.  No suprapubic or flank tenderness is noted on physical examination.  Laboratory results are as follows:

Renal function was normal at the time of hospital discharge.  A review of hospital records shows no significant hypotensive episodes or radiographic contrast exposure during the hospital stay.  Which of the following is the most likely cause of this patient’s renal dysfunction?

A 34-year-old male who is being treated for acute leukemia develops oliguria.  His serum creatinine level is 2.7 mg/dL.  Renal biopsy reveals multiple uric acid crystals obstructing renal tubular lumen.  The principal site of uric acid precipitation would be which of the following?

A 36-year-old woman comes to the office due to frequent urination since an exacerbation of multiple sclerosis 2 months ago.  Most of her symptoms, including dizziness, leg weakness, and numbness, have improved with corticosteroid treatment.  However, she has continued difficulty holding urine, and on several occasions has passed a small amount of urine while trying to reach the bathroom.  She has no urine leakage during coughing or sneezing.  The patient has no other medical problems.  Her abdomen is soft and nontender.  Neurological examination shows hyperreflexia and increased tone in the lower extremities.  Her postvoid residual volume is low.

Which of the following is the most likely explanation for her urinary symptoms?

A 44-year-old man is brought to the emergency department with fatigue, shortness of breath, and lethargy.  The patient had a brief upper respiratory illness about a month ago but began experiencing progressive dyspnea on exertion 2 weeks ago.  He has no significant medical history and takes no medications.  Blood pressure is 100/70 mm Hg and pulse is 95/min and regular.  The apical impulse is palpated in the sixth intercostal space along the left anterior axillary line.  An S3 is heard on cardiac auscultation.  Bibasilar crackles are present.  Distal extremities are cold, and there is 1+ peripheral edema.  Laboratory results are as follows:

Which of the following is most likely to be present in this patient compared to the normal state?