A 7 year old boy is referred to a specialty clinic because of digestive problems. He often experiences severe abdominal cramps after eating a high fat meal. He is worked up and diagnosed with a genetic defect resulting in a deficiency of lipoprotein lipase. Which of the following substances would most likely be elevated in this patient's plasma following a fatty meal?
After eating a high fat meal, triglycerides are processed by the intestinal mucosal cells. They are assembled in chylomicrons and eventually sent into the circulation for delivery to adipocytes and other cells. Chylomicrons are too large to enter cells, but are degraded while in the circulation by lipoprotein lipase. A defect in this enzyme would result in the accumulation of chylomicrons in the plasma. Albumin-bound free fatty acids (choice A) is incorrect because fatty acids leave the intestine esterified as triglycerides in chylomicrons. HDL is not a carrier of dietary fat from the intestine. LDL would be not be elevated in this patient after a high fat meal. However, VLDL would be elevated if the patient ate a high carbohydrate meal. In this situation, the carbohydrate would be conveed into fat in the liver and sent out into circulation as VLDL. VLDL would be unable to be degraded to LDL and, therefore, would accumulate. Ref: Botham K.M., Mayes P.A. (2011). Chapter 25. Lipid Transpo & Storage. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.
Albumin-bound free fatty acids
Chylomicrons
HDL
LDL