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Dyslipidemias: Pathology review




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Dyslipidemias: Pathology review


1 / 6 complete

USMLE® Step 1 style questions USMLE

6 questions

A 26-year-old man is evaluated in the emergency department for epigastric pain that began an hour ago. He reports that the pain radiates to the back and is 9 out of 10 in severity. The patient consumes a diet rich in fresh fruits and vegetables. He drinks 2-3 glasses of wine per week on social occasions. Family history is notable for recurrent episodes of pancreatitis in his father and paternal uncle. His temperature is 37.7°C (99.9°F), blood pressure is 125/83 mmHg, and pulse is 96/min. Physical examination is notable for tenderness on light palpation of the epigastric region. Abdominal exam also reveals hepatosplenomegaly and the following finding:  

Reproduced from: Wikimedia Commons  

Xanthomas are found on the patient’s bilateral elbows. Which of the following set of laboratory findings would be most likely expected in this patient?  


Content Reviewers:

Yifan Xiao, MD

Jamie is a 24-year-old male presenting to the emergency department complaining of sudden onset chest pain and shortness of breath when playing soccer.

On further evaluation, his ECG showed ST-segment elevation and laboratory evaluation showed elevated troponin I levels.

After instituting treatment, Jamie and his family inquire about the odd early onset of his disease.

The physical examination of the skin showed numerous xanthomas.

A lipid panel is ordered and shows marked elevation of LDL.

Jamie had a myocardial infarction which was caused by an underlying lipid disorder.

Lipid disorders include both hyper and hypolipidemia.

Hyperlipidemia can manifest as a high level of cholesterol, a high level of triglycerides, or a combination of both.

Hypolipidemia is the opposite where there’s a low level of these lipids.

So let’s do a quick overview of the physiology of lipid metabolism.

After eating a fatty meal, cholesterol and fatty acids enter the intestinal cells.

The fatty acids are assembled into triglycerides, and then they, along with a small amount of cholesterol, are packaged together with lipoproteins to form chylomicrons.

Chylomicrons move into the lymphatic vessels and eventually end up getting emptied into the left and right subclavian veins where they enter into the blood.

Now an enzyme in capillaries called lipoprotein lipase breaks down the chylomicrons to free the triglycerides, and then it also breaks the triglycerides down into fatty acids.

These can be taken up by nearby tissues to generate energy, like in the muscle cells, or for storage, like in adipocytes.

The remains of the chylomicrons will contain lipoproteins and a small amount of triglyceride and cholesterol, so these chylomicron remnants head to the liver to deposit the leftover lipid molecules.

The Liver is also synthesizing fatty acids and cholesterol and it will combine these with the ones from the chylomicron remnants and package them together.

But instead of chylomicrons, they are packaged into very low density lipoproteins, or VLDLs.

Compared to chylomicrons, these are made of different lipoproteins and contain a bit more cholesterol.

VLDLs are released from the liver and enter into the blood where lipoprotein lipase in the capillaries break them down again to release triglycerides for nearby tissue to use.

As more and more triglycerides leave the VLDL, it becomes an IDL or intermediate density lipoprotein, and when there’s more cholesterol left than triglyceride, it becomes an LDL.

LDLs then travel around in the blood, where they are endocytosed by cells with LDL receptors.

This can happen when they go back to the liver, or in peripheral tissues that need