A 9-year-old girl in a UAE hospital has her third attack of acute pancreatitis. Her parents are first cousins. Her drawn blood looks pink and milky, and her retinal vessels look pale (lipemia retinalis). Fasting results: triglyceride 31 mmol/L (2,746 mg/dL); total cholesterol 7.2 mmol/L (278 mg/dL). After the plasma stands overnight at 4 °C, a thick creamy layer floats on a clear infranatant. Post-heparin lipoprotein lipase activity is absent, even when the assay is supplied with apolipoprotein C-II. Thyroid, kidney and liver tests and fasting glucose are normal. The most likely diagnosis is:

Familial lipoprotein lipase deficiency

Familial dysbetalipoproteinemia

Familial type V hyperlipoproteinemia

Inherited apolipoprotein C-II deficiency

A 6-year-old with untreated nephrotic syndrome has serum albumin 15 g/L (1.5 g/dL), urine protein 4+, total cholesterol 10.2 mmol/L (394 mg/dL) and triglyceride 2.9 mmol/L (257 mg/dL). What best explains the lipid results?

Low oncotic pressure drives hepatic lipoprotein synthesis

LDL receptors are lost in the urine with the albumin

The low albumin activates lipoprotein lipase

Plasma is concentrated as fluid shifts into tissues

Dyslipidemias and cardiovascular risk

10 DOH Abu Dhabi (HAAD) lab licensing practice questions on Dyslipidemias and cardiovascular risk, part of Clinical Chemistry. The first 10 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
A 9-year-old girl in a UAE hospital has her third attack of acute pancreatitis. Her parents are first cousins. Her drawn blood looks pink and milky, and her retinal vessels look pale (lipemia retinalis). Fasting results: triglyceride 31 mmol/L (2,746 mg/dL); total cholesterol 7.2 mmol/L (278 mg/dL). After the plasma stands overnight at 4 °C, a thick creamy layer floats on a clear infranatant. Post-heparin lipoprotein lipase activity is absent, even when the assay is supplied with apolipoprotein C-II. Thyroid, kidney and liver tests and fasting glucose are normal. The most likely diagnosis is:
1. AFamilial lipoprotein lipase deficiency
2. BFamilial dysbetalipoproteinemia
3. CFamilial type V hyperlipoproteinemia
4. DInherited apolipoprotein C-II deficiency
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Answer: A · Familial lipoprotein lipase deficiency
A creamy layer over a clear infranatant after refrigeration means that chylomicrons alone are increased, the Fredrickson type I pattern. Chylomicrons are rich in triglyceride but carry little cholesterol, which fits a triglyceride of 31 mmol/L with only a moderately raised cholesterol, and such levels cause recurrent pancreatitis and lipemia retinalis. Type I disease in childhood with consanguineous parents points to a recessive defect in chylomicron clearance. Lipase activity that stays absent even when its activator, apolipoprotein C-II, is supplied shows that the enzyme itself is missing, whereas in apo C-II deficiency added C-II restores activity. Type V would leave a turbid infranatant from extra VLDL, and dysbetalipoproteinemia gives turbid plasma with a broad beta band and similar rises in cholesterol and triglyceride.
- B: Dysbetalipoproteinemia gives a broad beta band with cholesterol and triglyceride raised about equally.
- C: Type V adds VLDL, which leaves the infranatant turbid rather than clear.
- D: In apo C-II deficiency the enzyme is normal, so supplying C-II restores lipase activity.
Question 2 · Easy
Crops of small yellow papules on the buttocks and elbows (eruptive xanthomas) are a sign of:
1. AVery high triglyceride
2. BHigh lipoprotein(a)
3. CVery high LDL cholesterol
4. DVery low HDL cholesterol
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Answer: A · Very high triglyceride
Eruptive xanthomas appear when triglyceride is very high, usually above about 11 mmol/L (1,000 mg/dL), with chylomicrons in the plasma. They fade within weeks once triglyceride is brought down. Tendon xanthomas point to a high LDL, as in familial hypercholesterolemia, and palmar crease xanthomas to type III dysbetalipoproteinemia. Triglyceride at this level also carries a high risk of acute pancreatitis.
- B: A high lipoprotein(a) raises cardiovascular risk but causes no skin signs.
- C: Very high LDL causes tendon xanthomas and xanthelasma, not eruptive xanthomas.
- D: A low HDL on its own does not cause eruptive skin lesions.
Question 3 · Easy
In the Fredrickson classification, type IIa hyperlipoproteinemia is a raised:
1. ALDL and VLDL
2. BChylomicrons only
3. CVLDL only
4. DLDL only
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Answer: D · LDL only
Type IIa is a raised LDL with normal triglyceride, as in familial or polygenic hypercholesterolemia. Type IIb is raised LDL and VLDL, type IV raised VLDL, type I raised chylomicrons, type III raised remnants, and type V raised chylomicrons and VLDL. The Fredrickson type describes a pattern, not a cause. Secondary causes and the genetic cause still need to be looked for.
- A: Raised LDL and VLDL together is type IIb.
- B: Raised chylomicrons alone is type I.
- C: Raised VLDL alone is type IV.
Question 4 · Hard
A 6-year-old with untreated nephrotic syndrome has serum albumin 15 g/L (1.5 g/dL), urine protein 4+, total cholesterol 10.2 mmol/L (394 mg/dL) and triglyceride 2.9 mmol/L (257 mg/dL). What best explains the lipid results?
1. ALDL receptors are lost in the urine with the albumin
2. BLow oncotic pressure drives hepatic lipoprotein synthesis
3. CThe low albumin activates lipoprotein lipase
4. DPlasma is concentrated as fluid shifts into tissues
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Answer: B · Low oncotic pressure drives hepatic lipoprotein synthesis
In nephrotic syndrome the liver responds to low albumin and low oncotic pressure by making more albumin and more apo B lipoproteins, so VLDL and LDL rise. Clearance of triglyceride-rich lipoproteins also falls because lipoprotein lipase activity is reduced. The degree of hyperlipidemia is broadly inverse to the albumin and settles in remission. Lipid lost in the urine appears as oval fat bodies and Maltese-cross droplets under polarized light.
- A: LDL receptors are cell membrane proteins and are not lost in the urine.
- C: Lipoprotein lipase activity is reduced, not increased, in nephrotic syndrome.
- D: Fluid shifts cannot explain a cholesterol about twice the upper limit.
Question 5 · Hard
A 52-year-old man has yellow-orange creases on his palms. Fasting total cholesterol is 9.0 mmol/L (348 mg/dL) and triglyceride 4.0 mmol/L (354 mg/dL). Electrophoresis shows a broad beta band, and the ratio of VLDL cholesterol to plasma triglyceride (both in mg/dL) is 0.42, against a usual value of about 0.2. Which genotype is most likely?
1. AApo E2/E2
2. BApo E3/E3
3. CApo E4/E4
4. DLDLR heterozygote
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Answer: A · Apo E2/E2
Palmar crease xanthomas, cholesterol and triglyceride raised to similar values in mg/dL, a broad beta band and a VLDL cholesterol-to-triglyceride ratio above 0.3 are the signs of familial dysbetalipoproteinemia (type III). Apo E2 binds the LDL receptor very poorly, so cholesterol-rich remnants of VLDL and chylomicrons (beta-VLDL) build up. Most E2/E2 people never develop it; a second factor such as obesity, diabetes or hypothyroidism is usually needed. The Friedewald equation is not valid in this condition.
- B: Apo E3/E3 is the common genotype with normal remnant clearance.
- C: Apo E4 is linked to higher LDL and Alzheimer disease, not to remnant build-up.
- D: An LDL receptor variant raises LDL with normal triglyceride and no broad beta band.
Question 6 · Hard
A 7-year-old girl has yellow skin xanthomas on her knees and hands. Her LDL cholesterol is 16.8 mmol/L (650 mg/dL), and her parents' values are 5.9 and 6.3 mmol/L (228 and 244 mg/dL). The most likely diagnosis is:
1. AHomozygous familial hypercholesterolemia
2. BFamilial dysbetalipoproteinemia
3. CHeterozygous familial hypercholesterolemia
4. DFamilial combined hyperlipidemia
Answer and explanation in LearnFree account
Question 7 · Medium
During a cardiovascular risk assessment, a well-looking patient has an hs-CRP of 14 mg/L. Using the AHA/CDC risk bands (below 1, 1 to 3 and above 3 mg/L), the best action is to:
1. AReport it as very high risk for urgent review
2. BRepeat it in 2 weeks, once any inflammation settles
3. CRepeat it on a sample taken after fasting
4. DReport it as high cardiovascular risk
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Question 8 · Medium
In cholestasis, total cholesterol can rise steeply because of an abnormal particle rich in free cholesterol and phospholipid. This particle is:
1. ABeta-VLDL
2. BSmall dense LDL
3. CLipoprotein(a)
4. DLipoprotein X
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Question 9 · Hard
A 39-year-old man has a myocardial infarction; his father had one at 45. Results: LDL cholesterol 2.4 mmol/L (93 mg/dL; optimal below 2.6), HDL cholesterol 1.3 mmol/L (50 mg/dL; low below 1.0), triglyceride 1.1 mmol/L (97 mg/dL), hs-CRP 0.8 mg/L (low risk below 1), lipoprotein(a) 290 nmol/L (risk-enhancing at 125 nmol/L or more). Which result best explains his premature disease?
1. ALipoprotein(a)
2. Bhs-CRP
3. CHDL cholesterol
4. DLDL cholesterol
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Question 10 · Medium
A patient has high triglyceride and many small dense LDL particles, so LDL cholesterol may understate risk. Which test better reflects the number of atherogenic particles?
1. AApolipoprotein B
2. BHDL cholesterol
3. CTotal triglyceride
4. DApolipoprotein A-I
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Dyslipidemias and cardiovascular risk

Crops of small yellow papules on the buttocks and elbows (eruptive xanthomas) are a sign of:

In the Fredrickson classification, type IIa hyperlipoproteinemia is a raised:

A 6-year-old with untreated nephrotic syndrome has serum albumin 15 g/L (1.5 g/dL), urine protein 4+, total cholesterol 10.2 mmol/L (394 mg/dL) and triglyceride 2.9 mmol/L (257 mg/dL). What best explains the lipid results?

A 7-year-old girl has yellow skin xanthomas on her knees and hands. Her LDL cholesterol is 16.8 mmol/L (650 mg/dL), and her parents' values are 5.9 and 6.3 mmol/L (228 and 244 mg/dL). The most likely diagnosis is:

During a cardiovascular risk assessment, a well-looking patient has an hs-CRP of 14 mg/L. Using the AHA/CDC risk bands (below 1, 1 to 3 and above 3 mg/L), the best action is to:

In cholestasis, total cholesterol can rise steeply because of an abnormal particle rich in free cholesterol and phospholipid. This particle is:

A patient has high triglyceride and many small dense LDL particles, so LDL cholesterol may understate risk. Which test better reflects the number of atherogenic particles?