Pathology Handbook

Cholesterol (LDL)

Synonyms

Low Density Lipoprotein Cholesterol

Clinical Indications

Cholesterol circulates in blood bound to lipoproteins; the two main ones being low density lipoprotein (LDL) and high density lipoprotein (HDL). High levels of LDL are associated with a high risk of coronary disease.

Part of Profile

Fasting Lipids

Request Form

Request on ICE or use combined Biochemistry/Haematology form

Availability

On request

Patient Preparation

Patients must fast for 10 hours prior to blood collection (for follow up tests diabetic patients may not need to fast, but levels may be decreased as a result of recent food intake).

Turnaround Time

Same day

Specimen

Serum

Volume

2 ml

Container

Vacutainer gold top

Causes for Rejection

Unlabelled or incorrectly labelled sample

Reference Range

The concept of a reference range is flawed and acceptable levels depend on presence of other coronary risk factors. For patients with established coronary disease or diabetes, LDL cholesterol levels should be less than 3.0 mmol/L.. 

Calculation

LDL cholesterol is a calculated from other lipid parameters.  It should be remembered that the variability in measurement of these individual parameters is compounded in the LDL calculation and that small changes in LDL (<0.5 mmol/L) are clinically insignificant. 
LDL cannot be calculated when triglyceride levels are > 4.5 mmol/L

LDL Cholesterol = Total Cholesterol - HDL Chol - (Triglycerides / 2.19)