Non fasting lipids. Time for a change!

Last year the guidance from NICE and the Joint British Societies on cardiovascular risk (CVD) assessment changed to non-fasting samples for a lipid profile. The lipid profile should include measurement of total cholesterol, high density lipoprotein (HDL) cholesterol and triglyceride concentrations, with calculated non‑HDL-C and LDL-C. A fasting sample is not needed.

The reason for the change is non-HDL cholesterol is particularly relevant in type 2 diabetes because  the increase in atherogenic lipoproteins is not reflected by LDL-C. The JBS 3 calculator of CVD risk requires total cholesterol and HDL-C.

Screening for diabetes includes non fasting HbA1c which is more convenient for patients than fasting glucose and GTT. Simultaneous diabetes and CVD screening is advantageous, and there is an evidence base for CVD screening to be performed using non fasting lipids. This allows for sampling at any time of the day, with less patient waiting time (compared to the morning peak) and more patients being opportunistically screened.

Whether fasting or non fasting, there is no significant change in the total cholesterol and HDL-C in both non-diabetics & diabetics. Therefore for CVD risk assessment non fasting lipids can be used.

Non-HDL cholesterol is seen to be a better cardiovascular disease (CVD) risk indicator than low-density lipoprotein (LDL) cholesterol. It is more accurate, more practical and cost effective. A fasting blood sample is not needed.

Non fasting lipids have been linked directly to CVD and total mortality because triglyceride levels reflect remnant cholesterol. Both LDL cholesterol and remnant cholesterol are atherogenic as both these particles are taken up by the arterial endothelium.

Triglycerides are the mai lipid affected by food. A study of intra-individual daytime triglyceride variability showed minimal differences between triglycerides in samples collected fasting, before and three hours after lunch. Triglycerides did increase in the evening.

Non fasting lipids have been used in a number of major trials showing the efficacy of statin therapy and a meta-analysis showed no significant differences in events in the studies that used non fasting lipids.

Non fasting lipids used for screening will detect familial hypercholesterolaemia. The recommendations are that non fasting lipids be used for screening as this is common sense, cost effective, allows for opportunistic screening, is preferred for children and avoids patients needing to wait for testing during the peak morning time.

 

Jeffrey Barron, Consultant Chemical Pathologist locum, jeffrey.barron@sash.nhs.uk

Sunil Zachariah, Consultant Diabetologist & Endocrinologist, ESH

Ben Field, Consultant Diabetologist & Endocrinologist, ESH

James Clark, Consultant Diabetologist & Endocrinologist, ESH