Klinisk Biokemi i Norden · 2 2017
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fasting or fasting lipid profiles; if LDL cholesterol is
also calculated, then remnant cholesterol is equiva-
lent to triglycerides/2.2 in mmol/L and to triglyceri-
des/5 in mg/dL. Calculated remnant cholesterol is a
strong causal risk factor for cardiovascular disease
21-23
.
NonHDL cholesterol is calculated as total cholesterol
minus HDL cholesterol and is equivalent to LDL and
remnant cholesterol combined (Figure 1). The use of
nonHDL cholesterol for cardiovascular disease risk
prediction has been emphasized in several guidelines
and consensus papers
14-17
.
The most important additional measurement for
inclusion for cardiovascular disease risk prediction is:
• Lipoprotein(a) [Lp(a)]
This genetic, causal cardiovascular risk factor
13,24
should be measured at least once in all patients scree-
ned for cardiovascular risk
13
; it is noteworthy that
Lp(a) concentrations vary little over time (<10%) in any
individual. Lp(a) determination should not however be
included in repeated lipid profile measurements in the
same patient, unless therapeutic intervention is aimed
at reducing Lp(a) concentrations or in selected circum-
stances. Importantly, the cholesterol content of Lp(a),
corresponding to 30% of Lp(a) total mass
25
, is included
in total, nonHDL and LDL cholesterol values and its
apolipoprotein B content in the apolipoprotein B value.
Finally, measurements of apolipoprotein B and
apolipoprotein A1 can be used as alternatives to
nonHDL and HDL cholesterol measurements, respec-
tively (Figure 1)
15-17,26
, but these determinations come
at extra cost.
Why has fasting been the standard?
One reason among others for preferring fasting lipid
profiles is the increase in triglyceride concentration
Table 1. Key recommendations
Fasting is not required routinely for assessing the plasma lipid profile
When nonfasting plasma triglyceride concentration >5mmol/L(440mg/dL) consideration should be given to
repeating the lipid profile in the fasting state
Laboratory reports should flag abnormal values based on desirable concentration cut-points
Table 2. When to use nonfasting and fasting blood sampling to assess the plasma lipid profile
Patients for lipid profile testing
Nonfasting In most patients, including:
Initial lipid profile testing in any patient
For cardiovascular risk assessment
Patients admitted with acute coronary syndrome*
In children
If preferred by the patient
In diabetic patients
†
(due to hypoglycemic risk)
In the elderly
Patients on stable drug therapy
Fasting
Can sometimes be required if:
Nonfasting triglycerides >5 mmol/L (440 mg/dL)
Known hypertriglyceridemia followed in lipid clinic
Recovering from hypertriglyceridaemic pancreatitis
Starting medications that cause severe hypertriglyceridaemia
Additional laboratory tests are requested that require fasting
‡
or morning samples (e.g. fasting
glucose‡, therapeutic drug monitoring)
* Will need repeated lipid profile testing later because acute coronary syndrome lowers lipid concentrations
† Diabetic hypertriglyceridemia may be masked by fasting
‡ In many countries fasting blood sampling is restricted to very few analytes beside lipid profiles: one example is fasting glu-
cose; however, in many countries even fasting glucose measurement is being replaced by measurement of hemoglobin A1c
without the need to fast.
