Labs: Lipid Disorders

Question 1

After finding high lipid concentrations in the serum, what tests would you employ to confirm or exclude the secondary causes of hyperlipidemia?

Answer 1

-Obesity: measure waist circumference, BMI
-DM: random BGL -> fasting BGL -> OGTT
-Hypothyroidism: TSH, T3, T4
-Cushing: serum cortisol, ACTH tests
-Alcoholism: measure GGT
(Can also rule out primary / genetic hyperlipidemias: LDL, LPL, ApoC deficiencies)

Question 2

The laboratory parameters of a male person having normal blood pressure, BMI 23 kg/m2 are:
serum TG: 1.5 mmol/l
serum LDL cholesterol: 4.4 mmol/l
serum CRP: 5 mg/l
What is the risk of CHD for this person? What are the risk factors of atherosclerosis?

Answer 2

TG and BMI normal
LDL is high (>3.4 mmol/l)
CRP “normal” but > 3.0 mg/l cut-off for high risk of CHD

So high risk for CHD

Risk factors:
-Modifiable: smoking, exercise, hypertension, diet, weight, stress, DM type II
Non-modifiable: age, sex, genetics, other diseases

Question 3

A 45 year old man has the following parameters:
waist circumference: 110 cm
BP: 140/90 mmHg
HDLC: 0.9 mmol/l
fasting blood glucose: 6.3 mmol/l
What is your opinion about the risk of CHD for this person?

Answer 3

Waist: large (>102cm for male)
BP: mild hypertension
HDL low (<1 mM)
Glucose high (>6.0)

Meets 4 criteria of metabolic syndrome (not mentioned is high TAG), so high risk.

Question 4

A 35 year old man wanted to be screened for possible ischemic heart disease because his father died early from a heart attack. The patient was not obese and was a nonsmoker. On examination his blood pressure was normal and the only abnormality was tendon xanthoma arising from the Achilles tendons. An ECG taken at rest was normal but ischemic changes developed on exercise. Fasting lipids: serum cholesterol 8.7 mmol/l, triglyceride 1.1 mmol/l.
What is the most likely diagnosis and how can you confirm it?

Answer 4

High Se Chol (>5.2 mM), normal TAG -> type IIa hyperlipidemia, suggests Familial Hypercholesterolemia

Confirm via genetic testing of LDL-R or Apo-B mutation

Question 5

A middle-aged man saw his family doctor, because he got rashes. On examination he was found to have extensive yellowish papules, with an erythematous base, on his buttocks and elbows and orange-yellow discoloration of the palmar creases.
Fasting lipids: serum cholesterol 7.6 mmol/l, triglyceride 8.1 mmol/l.
What is your diagnosis?

Answer 5

Familial Type III hyperlipoproteinemia (ApoE2 defect)

High Se Chol (>5.2 mM), very high TG (>1.7 mM), xanthoma striatum palmare (discolored palmar crease)

Can test for mutated gene to confirm, also see if IDL is elevated.