Lipids

Purpose:
Measurement of lipids and lipoproteins is primarily used to estimate the risk of atherosclerotic cardiovascular disease and guide therapeutic decision-making (ESC/EAS 2019), and as part of the identification and management of patients with familial hypercholesterolaemia (NICE CG71).

2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk

Recommendation for lipid analyses for cardiovascular disease risk estimation	Class
TC is to be used for the estimation of total CV risk by means of the SCORE system.	I
HDL-C analysis is recommended to further refine risk estimation using the online SCORE system.	I
LDL-C analysis is recommended as the primary lipid analysis method for screening, diagnosis, and management.	I
TG analysis is recommended as part of the routine lipid analysis process.	I
Non-HDL-C evaluation is recommended for risk assessment, particularly in people with high TG levels, DM, obesity, or very low LDL-C levels.	I
ApoB analysis is recommended for risk assessment, particularly in people with high TG levels, DM, obesity, metabolic syndrome, or very low LDL-C levels. It can be used as an alternative to LDL-C, if available, as the primary measurement for screening, diagnosis, and management, and may be preferred over non-HDL-C in people with high TG levels, DM, obesity, or very low LDL-C levels.	I
Lp(a) measurement should be considered at least once in each adult person’s lifetime to identify those with very high inherited Lp(a) levels >180 mg/dL (>430 nmol/L) who may have a lifetime risk of ASCVD equivalent to the risk associated with heterozygous familial hypercholesterolaemia.	IIa
Lp(a) should be considered in selected patients with a family history of premature CVD, and for reclassification in people who are borderline between moderate and high-risk.	IIa

Apo = apolipoprotein; ASCVD = atherosclerotic cardiovascular disease; CV = cardiovascular; CVD = cardiovascular disease; DM = diabetes mellitus; HDL-C = high-density lipoprotein cholesterol; LDL-C = low-density lipoprotein cholesterol; Lp(a) = lipoprotein(a); SCORE = Systematic Coronary Risk Estimation; TC = total cholesterol; TG = triglyceride.

The UK Lipoprotein(a) Taskforce has published its first Call to Action report, encouraging greater recognition and acceptance of Lp(a) as an atherosclerotic cardiovascular disease (ASCVD) risk factor.

To address current variation in Lp(a) screening and measurement, HEART UK have recommended that Screening results are expressed in nmol/L of Lp(a) particles. Weqas have endorsed this recommendation and will now only accept results expressed in nmol/L to encourage participants to use the recommended units.

A standard serum lipid profile measures the concentration of TC and HDL-C, as well as TG. Plasma LDL-C can be either measured directly using enzymatic techniques or preparative ultracentrifugation, or calculated using the Friedewald formula. For the general population, calculated LDL-C and direct LDL-C show very strong correlations, however, calculated LDL-C has been found to underestimate LDL-C at concentrations of TG >2 mmol/L. Equally, at very low levels of LDL-C, calculated LDL-C may be misleading, especially in the presence of high TG. Global “cut off” for both risk and treatment targets are recommended, requiring accurate and precise methods for patient care. To facilitate this, the Centre for Disease Control and prevention, (CDC) provides a certification programme for manufacturers and clinical laboratories through its Cholesterol Reference Method Laboratory Network (CRML) programme.

Scope:
The Lipid Programme includes all routinely monitored analytes for the screening, diagnosis and management of dyslipidaemias by the clinical laboratory, covering all the measured and calculated parameters. Forty frozen endogenous (single or pooled) human serum samples and eight fresh single donor samples are distributed annually.
Reference target values using a CRML laboratory is provided for TC, and HDL-C. A wide clinically relevant range is distributed, along with samples with high TG concentration to challenge the TC and LDL-C methods.

The programme assesses both laboratory and method performance, including bias, within and between batch imprecision. Trueness is also assessed for a number of analytes using high metrological order Reference measurement systems.

A less rigorous separate programme is provided for POCT sites undertaking healthcare screening.

Key Features:

Liquid human serum samples requiring no prior preparation.
Commutable single and pooled donor samples.
Lipid profile includes all routinely monitored analytes and calculated parameters.
CDC reference values provided for Cholesterol, and HDL.
Traceable IDGCMS values provided for Cholesterol, Triglyceride and HDL.
Sigma metric scoring based on clinically relevant Milan Model 2 performance specification.

Frequency:
Monthly

Samples:
4 x 1.0mL

Material:
Off the clot human serum

Lipids Programme
Analyte	Approx. Range Covered
Cholesterol	2.5 - 9.5	mmol/L
Triglyceride	0.3 - 7.0	mmol/L
HDL cholesterol	0.6 - 2.5	mmol/L
LDL cholesterol	1.0 - 6.0	mmol/L
Apolipoprotein A1	0.8 - 2.4	g/L
Apolipoprotein B	0.3 - 2.0	g/L
Lipoprotein (a)	5 - 300	nmol/L
Non-HDL Cholesterol	1.5 - 6.5	mmol/L