Hyperlipidaemia

Keywords: Xanthelasma, Hypercholesterolaemia

Causes

Appropriate Tests

 

Lipid investigations should be done in patients with a personal or family history of atherosclerosis and patients with disease associated with hyperlipidaemia eg, diabetes mellitus, hypothyroidism, chronic renal disease, xanthomas.

The tests should not be performed on specimens collected between 24 hours and 8 weeks after myocardial infarction, as levels will be lower than usual.

The specimen is collected without venostasis, following a fast of at least 12 hours.

The initial screen is fasting plasma Cholesterol and Triglycerides, ideally with Cholesterol (HDL and LDL).

Apolipoprotein B can provide a measure of the number of attherogenic lipoprotein particles.

Plasma lipoprotein (a) is an independent risk factor for atherosclerosis and may be indicated in patients with a personal or strong family history of atherosclerosis, with normal Cholesterol (HDL and LDL).

Hypercholesterolaemia

Characterised by increased LDL cholesterol (type IIa pattern on lipoprotein electrophoresis).

Inherited
  • Familial hypercholesterolaemia
  • Familial combined hyperlipidaemia

 

Secondary causes
  • Hypothyroidism
  • Nephrotic syndrome
  • Cholestasis
  • Hypergammaglobulinaemia
  • Anorexia nervosa
  • Porphyria

 


Hypercholesterolaemia is due to lipoprotein X, rather than to elevated LDL cholesterol; further investigation is not indicated.

Hypertriglyceridaemia

Characterised by increased chylomicrons or VLDL.

Patients may also have Hypercholesterolaemia of chylomicron or VLDL origin, but LDL cholesterol is normal.

Inherited
  • Familial hyperchylomicronaemia
  • Familial hypertriglyceridaemia
  • Familial combined hyperlipidaemia


Post-heparin lipoprotein lipase, apolipoprotein C-II - consult pathologist.

Secondary causes
  • Alcohol
  • Obesity
  • Diabetes mellitus
  • Renal failure - chronic
  • Drug induced, especially
    • Oral contraceptives
    • Glucocorticoids
  • Nephrotic syndrome
  • Hypothyroidism
  • Cushing's syndrome
  • Pancreatitis
  • Acromegaly
  • Hypopituitarism
  • Hypergammaglobulinaemia
  • Glycogen storage diseases

See Alcoholism.












 

Hypercholesterolaemia and hypertriglyceridaemia

Characterised by increased LDL and VLDL, IDL, or VLDL and chylomicrons.

Inherited
  • Familial combined hyperlipidaemia
  • Familial dysbetalipoproteinaemia


ApoE genotyping (Molecular genetics; Apolipoprotein).

Secondary causes
  • Diabetes mellitus
  • Pancreatitis
  • Nephrotic syndrome
  • Hypothyroidism
  • Glucocorticoid therapy