CLINICAL PROBLEMS: Lipid Metabolism

1. A 7-year-old girl has a 1-month history of foul-smelling diarrhea. Upon further inquiry, the frequency seems to be 4–6 stools per day. She has also had trouble seeing at night in the past 2 weeks. Her WBC count is normal. Physical examination is entirely normal. Examination of a stool sample reveals that it is bulky and greasy. Analysis does not reveal any pathogenic microorganisms or parasites but confirms the presence of fats.

What condition would likely be revealed upon further evaluation of this patient?

a. Lactose intolerance
b. Biliary insufficiency
c. Ileal disease
d. Diabetes
e. Giardiasis

2. A 35-year-old man is brought to the emergency department in a confused and semicomatose state following a motor vehicle accident. His wife explains that he has type 1 diabetes mellitus. They were at a party earlier in the evening and both of them had two or three drinks. She is unsure whether he took his insulin before they left for the party. Physical examination reveals peripheral cyanosis and dehydration. While you are checking his abdomen, the patient doubles over and vomits. A fruity odor is detectable on his breath. A spot glucose reveals severe hyperglycemia.

Which substance would likely be revealed in abnormally high levels upon in the patient's urine test?
a. Protein
b. Hemoglobin
c. Acetoacetate
d. Lactate
e. Pyruvate

3. A 44-year-old Asian male is found to have a serum cholesterol of 350 mg/dL (normal <200 depending on criteria) after an overnight fast.

Which lipoprotein would contribute to plasma cholesterol in this man?
a. Very low density lipoproteins (VLDLs) and low-density lipoproteins (LDLs)
b. High-density lipoproteins (HDLs) and low-density lipoproteins (LDLs)
c. Chylomicrons and very low density lipoproteins (VLDLs)
d. Chylomicron remnants and very low density lipoproteins (VLDLs)
e. Low-density lipoproteins (LDLs) and adipocyte lipid droplets

4. A 12-year-old male presents with chest pain and xanthomas over his elbows and knees. His father died of a heart attack at age 34. His mother has high blood cholesterol. His physician suspects heterozygous familial hypercholesterolemia in the parents with homozygous disease in the son. This disease results from mutations in the receptor for low-density lipoprotein (LDL) or the ligand portion of its apoprotein coat.

Which apoprotein might be mutated?
a. AI
b. B100
c. B48
d. CII
e. E

5. Coronary artery disease is a multifactorial disorder involving occlusion of the coronary artery with atherosclerotic plaques. Several Mendelian disorders affecting lipid metabolism increase susceptibility for heart attacks, whereas environmental factors include smoking and high-fat diets. A 44-year-old woman has a mild heart attack and is placed on diet and statin therapy.

What will be the most likely result of this therapy?
a. High blood cholesterol
b. High blood glucose
c. Low blood glucose
d. Low blood LDLs
e. Low oxidation of fatty acids

6. Type III hyperlipidemia is caused by a deficiency of apoprotein E.

Which would be exhibited by analysis of the serum of patients with this disorder?
a. An absence of chylomicrons after eating
b. Higher than normal levels of VLDL after eating
c. Normal triglyceride levels
d. Elevated triglyceride levels
e. Lower than normal triglyceride levels

7. A molecule of palmitic acid, attached to carbon 1 of the glycerol moiety of a triacylglycerol, is ingested and digested. The fatty acid is stored in a fat cell and ultimately is oxidized to carbon dioxide and water in a muscle cell.

What would be the molecular complex in the blood in which the palmitate residue is carried from the lumen of the gut to the surface of the gut epithelial cell.
a. VLDL
b. Chylomicron
c. Fatty acid–albumin complex
d. Bile salt micelle
e. LDL

8. A patient with hyperlipoproteinemia would be most likely to benefit from a low-carbohydrate diet.

What lipoprotein likely elevated in blood of this patient?
a. Chylomicrons
b. VLDL
c. HDL
d. LDL
e. IDL

9. Major risk factors for the development of atherosclerotic cardiovascular disease (ASCVD) are sedentary lifestyle, obesity, cigarette smoking, diabetes mellitus, hypertension, and hyperlipidemia.

Which one, if present, is the only risk factor in a given patient without a history of having had a myocardial infarction that requires that the therapeutic goal for the serum LDL cholesterol level be 100 mg/dL?
a. Obesity
b. Cigarette smoking
c. Diabetes mellitus
d. Hypertension
e. Sedentary lifestyle