USMLE Step 1 Medical Subject Review
Physiology
Your brother-in-law calls you because he had health fair labs at work and the lab tech advised
him to see a health care provider for "out-of-range" values. He was told this problem could
put him at risk for heart disease, blockages in his blood vessels, and pancreatitis. He cannot
remember the value(s) that was/were out of normal range. He says he feels fine, but he
wants your advice. He is not worried; he reports that he has no medical conditions, and there
is no family history of cardiovascular disease. Your brother-in-law is 42 years old. He has a
BMI of around 30, and he is a non-smoker; he eats poorly, drinks moderate amounts of
alcohol, and does not exercise regularly. What is the most likely diagnosis?
Hypertriglyceridemia
This element is necessary for normal muscle and nerve function. Symptoms of deficiency
include muscle weakness, abnormal ECG, and alkaline urine
Potassium
3-year-old girl presents with a 5-day history of purulent, foul-smelling nasal discharge. She is
otherwise well-appearing, and her mother reports that she has not had any cough or fever.
She is playful and eating and drinking normally. She stays with a babysitter during the day.
Physical exam is remarkable for unilateral foul-smelling nasal discharge. What is the most
likely diagnosis?
Foreign body
30-year-old Hispanic woman asks for recommendations for contraception. She is a non-
smoker with a history of thrombophlebitis, obesity, and hypertension; there is also a maternal
family history of breast cancer. What method would have the best safety and effectiveness
profile for this patient?
Copper IUD (intrauterine device)
27-year-old man is admitted to the hospital following a motor vehicle accident. He sustained
lacerations to his arms bilaterally and has fractures of the right tibia and fibula. A cast is
placed and the patient is scheduled for surgery the following day. A few hours after the cast is
placed, he develops severe pain; the pain is unresponsive to several doses of intravenous
,morphine. His pain increases when he extends his right leg. Peripheral pulses are weak but
present. Based on the history and physical, what should be done next?
Remove cast and check compartment pressure.
An otherwise healthy 70-year-old man presents with age-related changes that are affecting
his ordinary activities of daily living. Those changes are most likely related to the function of
what organ system?
Urinary system
32-year-old pregnant woman is told by her physician to avoid taking aspirin. Use of aspirin is
contraindicated, especially during the last part of pregnancy. What hemotogic parameter is
affected by aspirin?
Bleeding time
35-year-old Hispanic man presents for an appointment but is too embarrassed to tell the
nurse his chief complaint. You enter the room and coerce him to give you the reason he has
come in to seek medical treatment. He admits to severe, intense itching around his anus that
has been worsening the last several weeks. He further states that he has noticed increasingly
severe and tearing pain in the anal area with each bowel movement. He would rank this pain
as a 10/10 on a pain scale and it lasts hours afterward. This intense pain makes him not want
to have any bowel movements. He admits to only 1 episode of a small amount of bright red
blood on the toilet paper as well as on the stool itself. The patient denies fever, diarrhea, or
ever being diagnosed with inflammatory bowel disease. What is this patient's most likely
diagnosis?
Anal fissure
43-year-old Caucasian man with a 20-year history of bipolar disorder presents for the first
time with long-term polyuria and polydipsia. He previously took lithium for mood
stabilization for 15 years before initiating divalproex sodium therapy. He stopped using
lithium because of the polyuria, but he felt that the polyuria never fully subsided. His weight
is stable, and he has no other urinary complaints. His blood pressure is 115/80 mm Hg, and
his physical exam is normal. His urinalysis shows no blood, cells, protein, glucose, nitrate,
casts, or crystals. What is the most likely cause of his polyuria?
Nephrogenic diabetes insipidus
19-year-old girl is brought to the emergency department by her sister who was unable to
wake her up in the morning. According to her sister, the patient came home the night before
with an alcoholic breath and was very upset after a fight with her boyfriend. She had always
,been healthy and does not use any medication, apart from occasional acetaminophen for
headaches. Her family has a strong history of diabetes and autoimmune disorders. Her father
has Hashimoto's thyroiditis and vitiligo, and her sister had a recent diagnosis of type 1
diabetes. Her grandmother, with whom she and her sister live, has been on insulin for several
years. An initial metabolic panel before administration of IV glucose showed blood glucose
levels of 1.77 mmol/L (32 mg/dL; normal, 70-115 mg/dL). C-peptide in the same sample was
undetectable (normal 0.9-4.0 ng/mL). What is the most likely cause for this patient's
hypoglycemia?
Exogenous insulin
44-year-old premenopausal Caucasian woman with a BMI of 36 presents with persistent
upper right quadrant abdominal pain that radiates to the back. It has gotten so bad that she
has difficulty eating any food and needs to force herself to eat. She has nausea with some
episodes of vomiting. She denies bulimia but admits to anorexia. On exam, the patient has a
positive Murphy's sign and tenderness to palpation in the epigastric and upper right quadrant
area. Patient has a slightly elevated temperature. The physician assistant is awaiting labs and
imaging. What is the most likely diagnosis?
Acute cholecystitis
62-year-old woman presents with excruciating pain, burning, and swelling in her left forearm
and wrist. She reports that symptoms initially began with a fracture 4 months ago. The
fracture has healed, and she is frustrated by ther persistent symptoms. She cannot wear a
jacket or long sleeves; the fabric touching her skin causes pain. Physical examination is
remarkable for mild edema and erythema of her left forearm and tenderness with light touch.
Distribution of findings includes the region from the elbow to wrist, anterior and posterior
surfaces. Her left wrist strength and range of motion are decreased compared to the right.
Distal pulses, capillary refill, and reflexes are normal. The remainder of the exam, including
mental status, is normal. What medication would be most appropriate for the most likely
diagnosis?
Gabapentin
32-year-old man with no significant past medical history presented with dyspnea,
palpitations, feelings of anxiety, and dizziness, all of which occurred earlier in the morning
following a brisk walk. He denied any prior episodes, recreational drug use, alcohol or
cigarette use, skipping meals, or caffeine intake. He further denied fever, chills, chest pain,
history of murmurs, cough, edema, rashes, syncope, headache, psychiatric, or focal
neurological problems. The physical examination demonstrated a fast and regular pulse with
a constant-intensity first heart sound, but was otherwise normal. An EKG was performed,
, which revealed a short PR interval and a slurred upstroke at the beginning of the QRS
complex. What is the most likely mechanism responsible for this patient's presentation?
Early excitation due to accessory pathways between the atria and ventricles
63-year-old woman is 4 days status post partial colectomy for colon cancer. Until now, her
postoperative course has been uncomplicated, but today she is experiencing new onset of
shortness of breath and chest pain. Her pulse is 120, respirations are 20, temperature is
38.6°C, and BP is 98/72. On examination, heart rate is regular but rapid. Her lung sounds are
diminished bilaterally; some wheezing is heard. Her abdomen is soft and mildly tender, with a
well-healing midline incision. EKG reveals sinus tachycardia. What is the gold standard test for
her suspected condition?
Pulmonary angiography
51-year-old woman presents with muscular weakness. Upon questioning, she acknowledges
that she usually awakens a couple of times at night to urinate. On physical examination, her
blood pressure is 163/97 mm Hg. Further workup is done, and she is found to have primary
aldosteronism, secondary to an adrenal adenoma. What electrolyte abnormality is probably
present?
Hypokalemia
34-year-old Caucasian man comes to you in the winter complaining of lack of energy, weight
loss, loss of appetite, nausea and vomiting, and increased skin pigmentation as if he had a
tan. On physical examination, his heart rate is 120, his blood pressure is 85/65. Blood tests
reveal that he is hyponatremic, hyperkalemic, has depressed cortisol, and elevated ACTH. The
most likely diagnosis is Addison disease most commonly caused by autoimmunity. This
condition would be MOST effectively treated by which of the following?
glucocorticoids and mineralocorticoids
40-year-old man is riding his bicycle and collides with a truck on the highway; he is severely
injured, leading to significant blood loss. He is immediately rushed to the nearest hospital,
where the attending resident immediately puts him on an intravenous supply of 0.9% NaCl
before arranging for the blood that matches his group. In this patient, what would the
intravenous administration of sodium chloride cause?
An increase in ECF volume with no change in osmolarity
47-year-old man presents with a 6-month history of intermittent abdominal pain. He notes
that his episodes of pain developed after eating large amounts at holiday parties or work
events. During episodes, his pain is located in the right upper quadrant without radiation, is
Physiology
Your brother-in-law calls you because he had health fair labs at work and the lab tech advised
him to see a health care provider for "out-of-range" values. He was told this problem could
put him at risk for heart disease, blockages in his blood vessels, and pancreatitis. He cannot
remember the value(s) that was/were out of normal range. He says he feels fine, but he
wants your advice. He is not worried; he reports that he has no medical conditions, and there
is no family history of cardiovascular disease. Your brother-in-law is 42 years old. He has a
BMI of around 30, and he is a non-smoker; he eats poorly, drinks moderate amounts of
alcohol, and does not exercise regularly. What is the most likely diagnosis?
Hypertriglyceridemia
This element is necessary for normal muscle and nerve function. Symptoms of deficiency
include muscle weakness, abnormal ECG, and alkaline urine
Potassium
3-year-old girl presents with a 5-day history of purulent, foul-smelling nasal discharge. She is
otherwise well-appearing, and her mother reports that she has not had any cough or fever.
She is playful and eating and drinking normally. She stays with a babysitter during the day.
Physical exam is remarkable for unilateral foul-smelling nasal discharge. What is the most
likely diagnosis?
Foreign body
30-year-old Hispanic woman asks for recommendations for contraception. She is a non-
smoker with a history of thrombophlebitis, obesity, and hypertension; there is also a maternal
family history of breast cancer. What method would have the best safety and effectiveness
profile for this patient?
Copper IUD (intrauterine device)
27-year-old man is admitted to the hospital following a motor vehicle accident. He sustained
lacerations to his arms bilaterally and has fractures of the right tibia and fibula. A cast is
placed and the patient is scheduled for surgery the following day. A few hours after the cast is
placed, he develops severe pain; the pain is unresponsive to several doses of intravenous
,morphine. His pain increases when he extends his right leg. Peripheral pulses are weak but
present. Based on the history and physical, what should be done next?
Remove cast and check compartment pressure.
An otherwise healthy 70-year-old man presents with age-related changes that are affecting
his ordinary activities of daily living. Those changes are most likely related to the function of
what organ system?
Urinary system
32-year-old pregnant woman is told by her physician to avoid taking aspirin. Use of aspirin is
contraindicated, especially during the last part of pregnancy. What hemotogic parameter is
affected by aspirin?
Bleeding time
35-year-old Hispanic man presents for an appointment but is too embarrassed to tell the
nurse his chief complaint. You enter the room and coerce him to give you the reason he has
come in to seek medical treatment. He admits to severe, intense itching around his anus that
has been worsening the last several weeks. He further states that he has noticed increasingly
severe and tearing pain in the anal area with each bowel movement. He would rank this pain
as a 10/10 on a pain scale and it lasts hours afterward. This intense pain makes him not want
to have any bowel movements. He admits to only 1 episode of a small amount of bright red
blood on the toilet paper as well as on the stool itself. The patient denies fever, diarrhea, or
ever being diagnosed with inflammatory bowel disease. What is this patient's most likely
diagnosis?
Anal fissure
43-year-old Caucasian man with a 20-year history of bipolar disorder presents for the first
time with long-term polyuria and polydipsia. He previously took lithium for mood
stabilization for 15 years before initiating divalproex sodium therapy. He stopped using
lithium because of the polyuria, but he felt that the polyuria never fully subsided. His weight
is stable, and he has no other urinary complaints. His blood pressure is 115/80 mm Hg, and
his physical exam is normal. His urinalysis shows no blood, cells, protein, glucose, nitrate,
casts, or crystals. What is the most likely cause of his polyuria?
Nephrogenic diabetes insipidus
19-year-old girl is brought to the emergency department by her sister who was unable to
wake her up in the morning. According to her sister, the patient came home the night before
with an alcoholic breath and was very upset after a fight with her boyfriend. She had always
,been healthy and does not use any medication, apart from occasional acetaminophen for
headaches. Her family has a strong history of diabetes and autoimmune disorders. Her father
has Hashimoto's thyroiditis and vitiligo, and her sister had a recent diagnosis of type 1
diabetes. Her grandmother, with whom she and her sister live, has been on insulin for several
years. An initial metabolic panel before administration of IV glucose showed blood glucose
levels of 1.77 mmol/L (32 mg/dL; normal, 70-115 mg/dL). C-peptide in the same sample was
undetectable (normal 0.9-4.0 ng/mL). What is the most likely cause for this patient's
hypoglycemia?
Exogenous insulin
44-year-old premenopausal Caucasian woman with a BMI of 36 presents with persistent
upper right quadrant abdominal pain that radiates to the back. It has gotten so bad that she
has difficulty eating any food and needs to force herself to eat. She has nausea with some
episodes of vomiting. She denies bulimia but admits to anorexia. On exam, the patient has a
positive Murphy's sign and tenderness to palpation in the epigastric and upper right quadrant
area. Patient has a slightly elevated temperature. The physician assistant is awaiting labs and
imaging. What is the most likely diagnosis?
Acute cholecystitis
62-year-old woman presents with excruciating pain, burning, and swelling in her left forearm
and wrist. She reports that symptoms initially began with a fracture 4 months ago. The
fracture has healed, and she is frustrated by ther persistent symptoms. She cannot wear a
jacket or long sleeves; the fabric touching her skin causes pain. Physical examination is
remarkable for mild edema and erythema of her left forearm and tenderness with light touch.
Distribution of findings includes the region from the elbow to wrist, anterior and posterior
surfaces. Her left wrist strength and range of motion are decreased compared to the right.
Distal pulses, capillary refill, and reflexes are normal. The remainder of the exam, including
mental status, is normal. What medication would be most appropriate for the most likely
diagnosis?
Gabapentin
32-year-old man with no significant past medical history presented with dyspnea,
palpitations, feelings of anxiety, and dizziness, all of which occurred earlier in the morning
following a brisk walk. He denied any prior episodes, recreational drug use, alcohol or
cigarette use, skipping meals, or caffeine intake. He further denied fever, chills, chest pain,
history of murmurs, cough, edema, rashes, syncope, headache, psychiatric, or focal
neurological problems. The physical examination demonstrated a fast and regular pulse with
a constant-intensity first heart sound, but was otherwise normal. An EKG was performed,
, which revealed a short PR interval and a slurred upstroke at the beginning of the QRS
complex. What is the most likely mechanism responsible for this patient's presentation?
Early excitation due to accessory pathways between the atria and ventricles
63-year-old woman is 4 days status post partial colectomy for colon cancer. Until now, her
postoperative course has been uncomplicated, but today she is experiencing new onset of
shortness of breath and chest pain. Her pulse is 120, respirations are 20, temperature is
38.6°C, and BP is 98/72. On examination, heart rate is regular but rapid. Her lung sounds are
diminished bilaterally; some wheezing is heard. Her abdomen is soft and mildly tender, with a
well-healing midline incision. EKG reveals sinus tachycardia. What is the gold standard test for
her suspected condition?
Pulmonary angiography
51-year-old woman presents with muscular weakness. Upon questioning, she acknowledges
that she usually awakens a couple of times at night to urinate. On physical examination, her
blood pressure is 163/97 mm Hg. Further workup is done, and she is found to have primary
aldosteronism, secondary to an adrenal adenoma. What electrolyte abnormality is probably
present?
Hypokalemia
34-year-old Caucasian man comes to you in the winter complaining of lack of energy, weight
loss, loss of appetite, nausea and vomiting, and increased skin pigmentation as if he had a
tan. On physical examination, his heart rate is 120, his blood pressure is 85/65. Blood tests
reveal that he is hyponatremic, hyperkalemic, has depressed cortisol, and elevated ACTH. The
most likely diagnosis is Addison disease most commonly caused by autoimmunity. This
condition would be MOST effectively treated by which of the following?
glucocorticoids and mineralocorticoids
40-year-old man is riding his bicycle and collides with a truck on the highway; he is severely
injured, leading to significant blood loss. He is immediately rushed to the nearest hospital,
where the attending resident immediately puts him on an intravenous supply of 0.9% NaCl
before arranging for the blood that matches his group. In this patient, what would the
intravenous administration of sodium chloride cause?
An increase in ECF volume with no change in osmolarity
47-year-old man presents with a 6-month history of intermittent abdominal pain. He notes
that his episodes of pain developed after eating large amounts at holiday parties or work
events. During episodes, his pain is located in the right upper quadrant without radiation, is
