Question

A young girl with a history of severe abdominal pain was taken to her local hospital at 5 a.m. in severe distress. Blood was drawn, and the plasma appeared milky, with the triacylglycerol level in excess of 2,000 mg/dl (normal = 4-150 mg/dl). The patient was placed on a diet severely limited in fat, but supplemented with medium-chain fatty acids.

1) Which of the following lipoprotein particles are most likely responsible for the appearance of the patient's plasma?

a. Very-low-density lipoproteins
b. Intermediate-density lipoproteins
c. Very-low-density lipoproteins
d. High-density-lipoproteins
e. Chylomicrons

2) Medium-chain fatty acids are given because they:

a. Can be converted into a variety of gluconeogenic precursors.
b. Are activators of lipoprotein lipase.
c. Stimulates VLDL production by the liver.
d. Are more efficiently packed into serum lipoproteins.
e. Enter directly into the portal blood, and can be metabolized by the liver.

Answer 1

Q1. Ans is E.

The milky appearance is due to triglyceride rich chylomicrons. VLDL, IDL, LDL mostly contains cholesterol esters and if they are raised, it will be reflected as hypercholesterolemia. Moreover, VLDL cannot cause milky appearance. There must be some issue, which inhibits the TG loaded chylomicrons in blood.

Q2. Ans is E.

Unlike long chain fatty acids present in normal fatty food which gets absorbed via lacteals and packaged into chylomicons), medium chain fatty acids are directly absorbed and enter the portal vein and this can be easily metabolised by the liver to produce energy.

It has been seen that medium chain fatty acids stimulates hormone sensitive lipase, not lipoprotein lipase.