A 66-year-old man with hypertension and stage IV chronic kidney disease comes to the office for follow-up.  The patient has had worsened fatigue and low energy over the past several months but no chest pain or shortness of breath.  He was previously nonadherent with antihypertensive therapy but has been following treatment recommendations since renal dysfunction was diagnosed 2 years ago.  Blood pressure is 126/78 mm Hg and pulse is 68/min.  Cardiac auscultation reveals an S4 sound.  The rest of the physical examination is unremarkable.  Laboratory results show normocytic, normochromic anemia with a low reticulocyte count.  Serum iron studies are within normal limits.  Treatment with a recombinant glycoprotein hormone is begun, and repeat laboratory testing several weeks later shows an improvement in hemoglobin level.  The effects of the hormone prescribed for this patient are most likely mediated by which of the following pathways?

A 34-year-old man is brought to the emergency department after a motor vehicle collision.  He has blunt abdominal trauma and bilateral femur fractures.  The patient has no significant medical history and takes no medications.  He does not smoke but drinks 8-12 alcoholic beverages a day.  Blood pressure is 80/40 mm Hg and pulse is 110/min.  Immediate resuscitation efforts are initiated, during which he receives transfusion of several units of packed red blood cells.  During transport to the intensive care unit, the patient reports a tingling sensation in his fingers and toes.  Serum ionized calcium level is 4 mg/dL (normal: 4.8-5.5).  Which of the following is the most likely cause of this patient’s current symptoms?

A 3-week-old girl is brought to the emergency department due to lethargy.  The patient was breastfeeding well until this morning when she became increasingly difficult to rouse.  She was born at term to a 35-year-old woman who had a spontaneous vaginal delivery at home.  The patient did not receive any vaccinations or medications after birth due to parental preference.  Head circumference is at the 99th percentile.  Weight and length are at the 25th percentile.  Temperature is 37 C (98.6 F).  Physical examination shows a large, bulging anterior fontanelle.  The eyes are driven downward, and the patient does not appear able to look upward.  No scalp swelling is present.  Intracranial hemorrhage is confirmed on CT scan of the head.  Which of the following is the most likely underlying cause of this patient’s condition?

A 26-year-old woman comes to the office for a follow-up appointment.  She has a history of immune thrombocytopenia that failed to improve with glucocorticoid therapy.  The patient underwent splenectomy 6 months ago, which resulted in improved platelet counts.  She received the recommended vaccinations after her surgery and currently feels well.  Physical examination shows no abnormalities.  A peripheral blood smear reveals many red blood cells of a specific morphology as indicated by the arrow below.

An increase in which of the following features best explains the presence of these abnormal cells?

A 62-year-old man comes to the office due to worsening fatigue.  The patient has long-standing type 2 diabetes mellitus complicated by nephropathy.  Laboratory results are as follows:

After appropriate treatment is initiated for his anemia, which of the following changes is most likely to occur in this patient’s erythroid cells?

A 28-year-old woman comes to the emergency department with acute-onset abdominal pain, nausea, and confusion.  She has no significant past medical history and does not use tobacco or alcohol as they have made her feel sick in the past.  Serum lipase and liver function tests are within normal limits.  CT scan of the abdomen shows no abnormalities.  A sample of her urine is reddish in color and darkens on standing for 24 hours.  Intravenous dextrose is administered and her symptoms improve significantly.  Dextrose infusion most likely improved this patient’s condition by affecting which of the following pathways?

A 1-year-old African American boy is brought to the emergency department by his parents with a 3-hour history of severe swelling and tenderness of the hands and feet.  They do not know what caused the swelling and say that the boy cries when his hands or feet are touched.  The patient has no history of recent illness and is up to date on all immunizations.  The boy attends day care, but his parents are unsure about any sick contacts.  His family history is significant for an older brother who died of pneumococcal sepsis at age 6.  Physical examination shows bilateral, severe swelling of the hands and feet.  Which of the following is most likely abnormal in this patient?

A 23-year-old Italian American man comes to the clinic for a follow-up visit.  He was found to have mild anemia during a routine checkup 3 weeks ago and was started on iron supplementation.  He has been taking the supplements as prescribed.  The patient has otherwise been well.  He feels that his energy levels are normal, and he has run several half-marathons in the last 2 years.  The patient’s initial hemoglobin level was 12.3 g/dL.  Laboratory results obtained during today’s visit are as follows:

The patient’s blood smear is shown in the image below.

Which of the following processes is the initial step in the pathogenesis of this patient’s disorder?

A 66-year-old man comes to the office due to several weeks of back and lower extremity pain.  The pain feels dull and achy and is worsened by movement, causing him to have difficulty bearing weight and ambulating.  He has had no bladder or bowel dysfunction, extremity weakness, or numbness.  The patient takes metformin for type 2 diabetes mellitus.  He drinks 2 alcoholic beverages daily.  Physical examination shows no gross abnormality or deformity of the back or extremities.  There is no swelling or redness of the legs, and neurological examination is normal.  A radiograph of the right lower extremity is shown in the exhibit.  Laboratory results are as follows:

Which of the following is the most likely explanation for this patient’s bone changes?

A 24-year-old woman is being evaluated for chronic fatigue.  She has a history of heavy menstrual periods since menarche and also recalls frequent nosebleeds as a child.  Her past medical history is otherwise insignificant and she takes no medications.  Laboratory studies show a hemoglobin level of 9.2 g/dL, a mean corpuscular volume of 72 fL, and decreased levels of ferritin.

Item 1 of 2

Which of the following is the most likely diagnosis?

Item 2 of 2

Further evaluation shows decreased von Willebrand factor activity in the patient’s serum.  This protein normally binds to which of the following?

A 64-year-old man is evaluated for a 1-month history of worsening fatigue and low back pain exacerbated by movement.  He has no prior medical history and takes no medications.  Vital signs are normal.  Physical examination shows mucosal pallor and bony tenderness.  Radiographs reveal lytic bone lesions.  Laboratory studies show that hemoglobin is 8.8 g/dL, serum creatinine is 3.0 g/dL, and serum calcium is 10.8 g/dL.  Urine dipstick is negative for protein, but quantitative measurement reveals elevated 24-hour urinary protein excretion.  Urine electrophoresis is most likely to detect which of the following?

A 3-year-old boy is brought to the physician with jaundice and pallor.  He was adopted and his family history is unknown.  Laboratory studies show anemia, reticulocytosis, and increased indirect bilirubin.  A peripheral blood smear shows red blood cells without central pallor.  This patient is most likely to have which of the following additional findings?

A 65-year-old man comes to the office due to several months of severe fatigue that limits his ability to do daily activities.  He has also had upper abdominal fullness, early satiety, and unintentional weight loss but no fever, night sweats, cough, or rash.  The patient has not seen a physician for many years.  He does not use tobacco, alcohol, or illicit drugs and is a retired chemical engineer.  Physical examination shows mucosal pallor with no scleral icterus.  The lungs are clear on auscultation, and heart sounds are normal.  There is mild hepatomegaly, and the spleen tip is palpable close to the midline of the abdomen.  Laboratory evaluation reveals pancytopenia.  Peripheral blood smear shows immature granulocytes, nucleated erythrocytes, and teardrop cells.  Bone marrow aspiration is attempted but yields no marrow.  Which of the following histopathological features is most likely to be present in this patient’s spleen?

A 5-year-old boy is brought to the emergency department due to 2 days of dark, low-volume urine and decreased energy.  The parents say that the boy had abdominal pain, fever, and bloody diarrhea for 4 days, which resolved about 3 days ago without treatment.  The day before the onset of symptoms, the patient swam in a lake and ate hamburgers at a family picnic.  His vital signs are within normal limits.  Physical examination shows pallor but is otherwise normal.  He has no peripheral edema or rashes.  Laboratory evaluation shows anemia, thrombocytopenia, and elevated blood urea nitrogen and serum creatinine.  Which of the following findings is most likely to be seen in this patient?

A 30-year-old woman comes to the emergency department with sudden-onset abdominal pain and ascites.  Laboratory studies show anemia, reticulocytosis, leukopenia, and thrombocytopenia.  Flow cytometry of the patient’s peripheral blood cells using the appropriate monoclonal antibodies shows CD55 and CD59 deficiency.  CT scan of the abdomen shows hepatic vein thrombosis.  Which of the following is the most likely cause of this patient’s anemia?

A 32-year-old woman comes to the office due to several days of fatigue and malaise.  She has no significant medical history and has had no recent sick contacts.  The patient does not appear to be in acute distress.  Evaluation reveals severe thrombocytopenia.  Thrombotic thrombocytopenic purpura is suspected.  Which of the following findings is required to make the diagnosis?

A 45-year-old man comes to the office for evaluation of fatigue that has been gradually increasing over the past 4 months.  The patient has had difficulty keeping up with the labor involved with his job as a construction worker.  Over the past 2 weeks, he has been unable to climb past the second floor of the building his company is renovating.  The patient also has increasing shortness of breath with minor activities, such as lifting his toolbox out of the car.  Review of systems reveals constipation and decreased concentration.  Physical examination shows an overweight male with conjunctival pallor who has difficulty getting onto the examination table due to shortness of breath.  Laboratory test results are as follows:

Which of the following findings would most likely be seen on this patient’s peripheral blood smear?

A 67-year-old man is evaluated for persistent lower back pain and fatigue.  The patient has no other medical conditions and takes no medications.  Laboratory testing shows anemia and renal dysfunction.  Serum total protein levels are elevated, and electrophoresis of the serum proteins reveals a narrow spike in the gamma globulin region.  A subsequent bone marrow biopsy shows abnormal marrow cells.  A medication that blocks cellular proteasome action is administered.  This treatment is most likely to cause which of the following effects on the abnormal cells?

A 34-year-old man diagnosed with advanced non-Hodgkin lymphoma undergoes doxorubicin-containing chemotherapy with good clinical response.  Several weeks after the last chemotherapy cycle, the patient comes to the office with progressive exertional dyspnea.  He has difficulty sleeping flat at night and needs to use multiple pillows to fall asleep.  The patient is a lifetime nonsmoker and has no family history of heart disease.  Blood pressure is 124/72 mm Hg, pulse is 86/min, and respirations are 16/min.  Oxygen saturation on room air is 96%.  Which of the following is most likely responsible for this patient’s current symptoms?

A 45-year-old man is brought to a rural emergency department due to severe chest pain, sweating, and nausea.  The symptoms began suddenly an hour ago.  He has no significant medical history.  His father died at age 50 after experiencing sudden-onset chest pain.  The patient smokes a pack of cigarettes daily.  He does not take any medications and has no known drug allergies.  Examination shows normal heart sounds and breath sounds.  ECG shows sinus tachycardia with ST segment elevation in leads II, III, and aVF.  Medical management for the patient’s acute condition is initiated.  After initial treatment, the chest pain decreases in intensity and a reperfusion complex ventricular arrhythmia emerges.  The arrhythmia is asymptomatic and resolves spontaneously.  Which of the following drugs is most likely responsible for rapid reperfusion in this patient?

A 68-year-old man comes to the emergency department due to lightheadedness, generalized weakness, and palpitations.  The patient has a prolonged history of hypertension and takes amlodipine.  He does not use tobacco or alcohol.  His blood pressure is 110/60 mm Hg and pulse is 144/min and irregular.  ECG shows an irregularly irregular rhythm and absent P waves.  The patient is started on beta blocker therapy for rate control, with improvement in his heart rate.  Long-term anticoagulation is initiated to prevent atrial thrombus formation, and he is eventually discharged home on warfarin.  Which of the following is the best test to monitor the anticoagulation effect of warfarin in this patient?

A 24-year-old woman comes to the emergency department due to bloody emesis.  She had 2 episodes of vomiting bright red blood and feels lightheaded and dizzy.  The patient was recently diagnosed with factitious disorder after being hospitalized multiple times for a myriad of symptoms and undergoing several invasive procedures.  Physical examination shows scattered ecchymoses.  The abdomen is soft and nontender.  Rectal examination shows maroon-colored, guaiac-positive stool.  After much questioning, she admits to having ingested rat poison several days ago.  Immediate treatment of this patient should include which of the following?

A 64-year-old man comes to the office due to exertional chest pain over the last 6 months.  He is a lifelong 1 pack per day cigarette smoker and has a history of type 2 diabetes mellitus and peripheral artery disease.  The patient undergoes treadmill exercise stress testing and develops substernal chest pain on moderate exertion accompanied by ECG changes that resolve immediately upon rest.  He refuses invasive cardiac testing.  The patient is started on low-dose aspirin therapy for secondary prevention of cardiovascular disease but experiences shortness of breath and wheezing with the medication.  Which of the following is the best alternate therapy for this patient?

A 68-year-old man comes to the office due to thigh and leg pain that worsens with exertion.  He is unable to walk through the local mall with his wife without discomfort.  Past medical history is significant for hypertension and diabetes mellitus.  The patient smokes 2 packs of cigarettes a day and consumes alcohol occasionally.  Physical examination of the extremities shows weak dorsalis pedis pulses in both feet.  Further evaluation confirms moderate peripheral arterial disease involving both lower extremities.  Which of the following drugs would best provide symptomatic improvement due to direct dilation of arteries and inhibition of platelet aggregation?

A 76-year-old man is brought to the emergency department with severe midsternal chest pain and diaphoresis.  Past medical history is significant for hypertension, type 2 diabetes mellitus, and asymptomatic right carotid artery stenosis.  His blood pressure is 120/70 mm Hg and pulse is 75/min.  Lungs are clear on auscultation.  ECG shows ST segment elevations greater than 1 mm in leads II, III, and aVF.  The patient receives aspirin immediately upon arrival followed by alteplase and a low-dose beta blocker.  A single dose of intravenous morphine is given for pain control.  Several hours later, the patient is found to be comatose with asymmetric pupils and an irregular breathing pattern.  What is the most likely cause of this patient’s current condition?

A 50-year-old woman comes to the emergency department due to a large, painful skin lesion.  She does not remember sustaining any trauma.  She was recently diagnosed with atrial fibrillation and started on treatment with warfarin.  The patient noticed the lesion about a day and a half after starting the medication.  Temperature is 36.7 C (98 F), blood pressure is 130/82 mm Hg, and pulse is 88/min and irregularly irregular.  Physical examination findings are shown in the image below.

The remainder of the skin examination is normal.  Which of the following is the most likely cause of this patient’s skin lesion?

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