This is what NICE has to say about it.
Lipid measurement and referral
1.3.3 Measure both total and high‑density lipoprotein (HDL) cholesterol to achieve the best estimate of CVD risk.
[2008]
1.3.4 Before starting lipid modification therapy for the primary prevention of CVD, take at least 1 lipid sample to measure a full lipid profile. This should include measurement of total cholesterol, HDL cholesterol, non‑HDL cholesterol and triglyceride concentrations. A fasting sample is not needed.
[new 2014]
For information about implementing this recommendation, see
implementation: getting started.
1.3.5 Use the clinical findings, lipid profile and family history to judge the likelihood of a familial lipid disorder rather than the use of strict lipid cut‑off values alone.
[new 2014]
1.3.6 Exclude possible common secondary causes of dyslipidaemia (such as excess alcohol, uncontrolled diabetes, hypothyroidism, liver disease and nephrotic syndrome) before referring for specialist review.
[new 2014]
1.3.7 Consider the possibility of familial hypercholesterolaemia and investigate as described in
familial hypercholesterolaemia (NICE guideline CG71) if they have:
- a total cholesterol concentration more than 7.5 mmol/litre and
- a family history of premature coronary heart disease. [new 2014]
1.3.8 Arrange for specialist assessment of people with a total cholesterol concentration of more than 9.0 mmol/litre or a non‑HDL cholesterol concentration of more than 7.5 mmol/litre even in the absence of a first‑degree family history of premature coronary heart disease.
[new 2014]
1.3.9 Refer for urgent specialist review if a person has a triglyceride concentration of more than 20 mmol/litre that is not a result of excess alcohol or poor glycaemic control. [new 2014]
1.3.10 In people with a triglyceride concentration between 10 and 20 mmol/litre:
- repeat the triglyceride measurement with a fasting test (after an interval of 5 days, but within 2 weeks) and
- review for potential secondary causes of hyperlipidaemia and
- seek specialist advice if the triglyceride concentration remains above 10 mmol/litre. [new 2014]
1.3.11 In people with a triglyceride concentration between 4.5 and 9.9 mmol/litre:
- be aware that the CVD risk may be underestimated by risk assessment tools and
- optimise the management of other CVD risk factors present and
- seek specialist advice if non‑HDL cholesterol concentration is more than 7.5 mmol/litre. [new 2014]
https://www.nice.org.uk/guidance/cg...d-assessing-cardiovascular-disease-cvd-risk-2
.