CLS Diagnosis & Classification of Dyslipidemia 2 — Questions and Answers
Question 1: A patient has triglycerides of 950 mg/dL. According to the Endocrine Society classification, this level is best described as:
- Borderline high
- High
- Very high
- Severe hypertriglyceridemia (Correct answer)
Correct answer: Severe hypertriglyceridemia
Triglycerides ≥500 mg/dL are classified as very high (severe hypertriglyceridemia), which carries risk of pancreatitis.
Question 2: Which lipoprotein pattern is characterized by elevated VLDL and chylomicrons, causing a creamy supernatant and turbid infranatant on refrigerated plasma?
- Fredrickson Type IIb
- Fredrickson Type III
- Fredrickson Type IV
- Fredrickson Type V (Correct answer)
Correct answer: Fredrickson Type V
Fredrickson Type V involves elevations of both VLDL and chylomicrons, producing the classic creamy top layer and turbid bottom on standing plasma.
Question 3: A patient on a standard fasting lipid panel shows total cholesterol 240 mg/dL, triglycerides 130 mg/dL, HDL 45 mg/dL. The Friedewald-estimated LDL-C would be approximately:
- 169 mg/dL (Correct answer)
- 165 mg/dL
- 171 mg/dL
- 149 mg/dL
Correct answer: 169 mg/dL
Friedewald formula: LDL = TC − HDL − (TG/5) = 240 − 45 − 26 = 169 mg/dL.
Question 4: Which of the following conditions most commonly causes secondary hypercholesterolemia?
- Chronic kidney disease
- Hypothyroidism (Correct answer)
- Type 1 diabetes
- Obesity
Correct answer: Hypothyroidism
Hypothyroidism decreases LDL receptor activity and lipoprotein lipase activity, leading to elevated LDL-C and sometimes TG.
Question 5: In the classification of dyslipidemias, 'dysbetalipoproteinemia' is synonymous with which Fredrickson phenotype?
- Type IIa
- Type IIb
- Type III (Correct answer)
- Type IV
Correct answer: Type III
Type III hyperlipoproteinemia (dysbetalipoproteinemia) is characterized by accumulation of IDL/remnant particles and is associated with apoE2/E2 homozygosity.
Question 6: A non-HDL cholesterol level of 190 mg/dL in a patient with TG of 300 mg/dL would classify as:
- Near optimal
- Borderline high
- High (Correct answer)
- Very high
Correct answer: High
Non-HDL-C of 160–189 mg/dL is borderline high; ≥190 mg/dL is classified as high per ATP III/ACC-AHA thresholds.
Question 7: Which genetic mutation is the most frequent cause of familial hypercholesterolemia in the general population?
- APOB mutations
- LDLR mutations (Correct answer)
- PCSK9 gain-of-function mutations
- LIPA mutations
Correct answer: LDLR mutations
Mutations in the LDL receptor gene (LDLR) account for approximately 85–90% of molecularly confirmed familial hypercholesterolemia cases.
CLS Diagnosis & Classification of Dyslipidemia 2
A patient has triglycerides of 950 mg/dL.
According to the Endocrine Society classification, this level is best described as: