Lipid metabolism Practice Questions

Question 1

A 15-year-old boy is brought to the emergency department by his parents because of lethargy, repeated vomiting, and abdominal pain for 6 hours. Over the past 2 weeks, he has reported increased urinary frequency to his parents that they attributed to his increased oral fluid intake. Examination shows dry mucous membranes and rapid, deep breathing. Laboratory studies show the presence of acetoacetate in the urine. Which of the following cells is unable to use this molecule for energy production?

Accepted Answer

Hepatocyte

Answer

Myocyte

Answer

Adipocyte

Answer

Neuron

Answer

Thrombocyte

Question 2

A 63-year-old man with high blood pressure, dyslipidemia, and diabetes presents to the clinic for routine follow-up. He has no current complaints and has been compliant with his chronic medications. His blood pressure is 132/87 mm Hg and his pulse is 75/min and regular. On physical examination, you notice that he has xanthelasmas on both of his eyelids. He currently uses a statin to lower his LDL but has not reached the LDL goal you have set for him. You would like to add an additional medication for LDL control. Of the following, which statement regarding fibrates is true?

Accepted Answer

Fibrates can potentiate the risk of myositis when given with statins

Answer

Fibrates inhibit the rate-limiting step in cholesterol synthesis

Answer

Fibrates can cause significant skin flushing and pruritus

Answer

Fibrates can increase the risk of cataracts

Answer

The primary effect of fibrates is to lower LDL

Question 3

A 24-year-old man presents for an annual check-up. He is a bodybuilder and tells you he is on a protein-rich diet that only allows for minimal carbohydrate intake. His friend suggests he try exogenous glucagon to help him lose some excess weight before an upcoming competition. Which of the following effects of glucagon is he attempting to exploit?

Accepted Answer

Increased lipolysis in adipose tissues

Answer

Increased glucose utilization by tissues

Answer

Decreased blood cholesterol level

Answer

Increased hepatic gluconeogenesis

Answer

Increased hepatic glycogenolysis

Question 4

A 57-year-old man presents to his family physician for a checkup. He has had type 2 diabetes mellitus for 13 years, for which he has been taking metformin and vildagliptin. He has smoked 10–15 cigarettes daily for 29 years. Family history is irrelevant. Vital signs include: temperature 36.6°C (97.8°F), blood pressure 152/87 mm Hg and pulse 88/min. Examination reveals moderate abdominal obesity with a body mass index of 32 kg/m². The remainder of the examination is unremarkable. His fasting lipid profile is shown:
Total cholesterol (TC) 280 mg/dL
Low-density lipoprotein (LDL)-cholesterol 210 mg/dL
High-density lipoprotein (HDL)-cholesterol 40 mg/dL
Triglycerides (TGs) 230 mg/dL
Which of the following is the mechanism of action of the best initial therapy for this patient?

Accepted Answer

Inhibition of cholesterol synthesis

Answer

Activation of PPAR-alpha

Answer

Inhibition of cholesterol absorption

Answer

Bile acid sequestration

Answer

Inhibition of adipose tissue lipolysis

Question 5

A 50-year-old man comes to the physician for his annual health maintenance examination. The patient feels well. He has a history of hypertension, for which he currently takes lisinopril. He has smoked a pack of cigarettes daily for 20 years. He drinks 5–6 beers on weekends. He is 181 cm tall (5 ft 11 in), weighs 80 kg (176.4 lbs); BMI is 24.6 kg/m2. His pulse is 75/min, blood pressure is 140/85 mm Hg, and respirations are 18/min. Physical examination is unremarkable. Laboratory studies show:
Total cholesterol 263 mg/dL
High-density lipoprotein cholesterol 36 mg/dL
Triglycerides 180 mg/dL
In addition to dietary and lifestyle modification, administration of which of the following agents is the most appropriate next step in management?

Accepted Answer

HMG-CoA reductase inhibitor

Answer

Peroxisome proliferator-activated receptor alpha activator

Answer

Proprotein convertase subtilisin kexin 9 inhibitor

Answer

Bile acid resins

Answer

Cholesterol absorption inhibitor

Question 6

A 58-year-old woman presents to the physician for a routine health maintenance examination. She has a history of dyslipidemia and chronic hypertension. Her medications include atorvastatin, hydrochlorothiazide, and lisinopril. She exercises every day and follows a healthy diet. She does not smoke. There is no family history of chronic disease. Her blood pressure is 130/80 mm Hg, which is confirmed on repeat measurement. Her BMI is 22 kg/m2. The physical examination shows no abnormal findings. The laboratory test results show:
Serum  
Total cholesterol 193 mg/dL
Low-density lipoprotein (LDL-C) 124 mg/dL
High-density lipoprotein (HDL-C) 40 mg/dL
Triglycerides 148 mg/dL
The patient's 10-year risk of cardiovascular disease (CVD) is 4.6%. Which of the following is the most appropriate next step in pharmacotherapy?

Accepted Answer

Ezetimibe

Answer

Fish oils

Answer

No additional pharmacotherapy at this time

Answer

Niacin

Answer

Fenofibrate

Question 7

A 12-year-old girl comes to the clinic with a grossly enlarged abdomen. She has a history of frequent episodes of weakness, sweating, and pallor that are eliminated by eating. Her development has been slow. She started to walk unassisted at 2 years and was not performing well at school. Physical examination reveals a blood pressure of 100/60 mm Hg, heart rate of 80/min, and temperature of 36.9°C (98.4℉). On physical examination, the liver is enlarged, firm, and palpable up to the pelvis. The spleen and kidney are not palpable. Laboratory investigation reveals low blood glucose and pH with high lactate, triglycerides, ketones, and free fatty acids. The liver biopsy revealed high glycogen content. Hepatic glycogen structure was normal. The enzyme assay performed on the biopsy tissue revealed very low glucose-6-phosphatase levels. What is the most likely diagnosis?

Accepted Answer

Von-Gierke's disease

Answer

Pompe's disease

Answer

Cori's disease

Answer

Hereditary hemochromatosis

Answer

McArdle disease

Question 8

A 5-month-old boy presents with increasing weakness for the past 3 months. The patient’s mother says that the weakness is accompanied by dizziness, sweating, and vertigo early in the morning. Physical examination shows hepatomegaly. Laboratory findings show an increased amount of lactate, uric acid, and elevated triglyceride levels. Which of the following enzymes is most likely deficient in this patient?

Accepted Answer

Glucose-6-phosphatase

Answer

Hepatic glycogen phosphorylase

Answer

Debranching enzyme

Answer

Muscle glycogen phosphorylase

Answer

Lysosomal α-1,4-glucosidase

Question 9

A 12-year-old boy is brought to the physician because of difficulty in walking for 5 months. His mother reports that he has trouble keeping his balance and walking without support. Over the past year, he has started to have difficulty seeing in the dark and his hearing has been impaired. Examination shows marked scaling of the skin on the face and feet and a shortened 4th toe. Muscle strength is 3/5 in the lower extremities and 4/5 in the upper extremities. Sensation to pinprick is symmetrically decreased over the legs. Fundoscopy shows peripheral pigment deposits and retinal atrophy. His serum phytanic acid concentration is markedly elevated. The patient's condition is most likely caused by a defect in which of the following cellular structures?

Accepted Answer

Peroxisomes

Answer

Proteasomes

Answer

Smooth endoplasmic reticulum

Answer

Mitochondria

Answer

Myofilaments

Question 10

A 34-year-old male visits the clinic with complaints of intermittent diarrhea over the past 6 months. He has lost 6.8 kg (15 lb) over that time period. His frequent bowel movements are affecting his social life and he would like definitive treatment. Past medical history is significant for chronic type 2 diabetes that is well controlled with insulin. No other family member has a similar condition. He does not smoke tobacco and drinks alcohol only on weekends. Today, his vitals are within normal limits. On physical exam, he appears gaunt and anxious. His heart has a regular rate and rhythm and his lungs are clear to auscultation bilaterally. Additionally, the patient has a red-purple rash on his lower abdomen, groin, and the dorsum of both hands. The rash consists of pruritic annular lesions. He is referred to a dermatologist for core biopsy which is consistent with necrolytic migratory erythema. Further workup reveals a large hormone secreting mass in the tail of his pancreas. Which of the following is the action of the hormone that is in excess in this patient?

Accepted Answer

Stimulation of lipolysis

Answer

Activation of glycogen synthase

Answer

Inhibition of gluconeogenesis

Answer

Inhibition of insulin secretion

Answer

Inhibition of acetone production

Lipid metabolism

Study Resources

Lessons

Questions

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Lessons

Fatty acid oxidation (beta-oxidation)

Fatty acid synthesis

Ketone body metabolism

Cholesterol synthesis and regulation

Lipoprotein metabolism

Phospholipid metabolism

Eicosanoid synthesis and function

Steroid hormone synthesis

Adipose tissue metabolism

Brown vs. white adipose tissue

Disorders of lipid metabolism

Integration with carbohydrate metabolism

Practice Questions

Flashcards

About Lipid metabolism for USMLE

Lessons in Lipid metabolism

Master Lipid metabolism