Hyperlipidaemia

Last updated: Monday, 13, December, 2010

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 HDL cholesterol and LDL cholesterol. Lipoprotein electrophoresis is indicated only if the triglyceride level is >4mmol/L. Apolipoprotein A1 and B can be measured instead of HDL and LDL cholesterol, but there is no advantage in doing so unless familial hyperapolipoproteinaemia B (normal LDL cholesterol, increased apolipoprotein B) is suspected. 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 LDL and HDL cholesterol.
Hypercholesterolaemia	Characterised by increased LDL (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; further investigation is not indicated.
Hypertriglyceridaemia	Characterised by increased chylomicrons or VLDL (type I or IV pattern on lipoprotein electrophoresis). 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 CII - 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 (type IIb, III, or V patterns respectively on lipoprotein electrophoresis).
Inherited Familial combined hyperlipidaemia Familial dysbetalipoproteinaemia	Apo E phenotyping or genotyping.
Secondary causes Diabetes mellitus Pancreatitis Nephrotic syndrome Hypothyroidism Glucocorticoid therapy

Glossary Terms

HDL :

High density lipoprotein

IDL :

Intermediate density lipoprotein

IV :

Intravenous

LDL :

Low density lipoprotein

VLDL :

Very low density lipoprotein