or high blood cholesterol levels are a risk for cardiovascular diseases like heart attack and stroke. Cholesterol thickens and narrows blood vessels thereby reducing blood flow and oxygen supply to various parts of the body. Organs like the heart and the brain are particularly sensitive to low oxygen levels. High triglycerides are a risk factor for pancreatitis
. A lipid profile should, therefore, be included as a part of a routine preventive health checkup.
‘A cholesterol test can be done in the non-fasting state, and in fact may be even more accurate than when done in the fasting state.’
A typical lipid
profile measures total cholesterol, low-density
lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and
triglycerides. Remnant cholesterol and non-HDL cholesterol which are important
determinants of cardiovascular risk are calculated based on these results.
Lipoprotein (a) [Lp (a)] levels should be measured once but need not be
repeated. Apolipoprotein B and apolipoprotein A1 estimation may be used instead
of non-HDL and HDL cholesterol estimation, respectively.
Recommendations in Denmark suggest that lipid levels
should be measured in the non-fasting state rather than in the fasting state
. Since people eat several meals a day with snack breaks in between,
on an average, more time is spent in a non-fasting than a fasting state.
Therefore, non-fasting levels may provide a more accurate picture of the lipid
profile. A repeat test in the fasting state may be required in patients with
very high triglyceride levels.
Some studies indicate that measurement of non-fasting
levels is more indicative of cardiovascular risk as compared to fasting levels
. Measurement of cholesterol in the non-fasting state has some practical advantages as well
The patient can combine the testing with a routine visit to the doctor and does not have to go in separately only for the test. The trouble of going to the laboratory in a fasting state, only to find out that you are not the first and will have to bear the rumbles in your stomach for some more time can be avoided. A diabetes patient is saved from the risk of hypoglycemia
or low blood sugar levels.
non-fasting lipid test may be more convenient for the patient, who is likely to
do it more regularly and thereby receive appropriate and adequate treatment.
Several other blood tests like hemoglobin A1c also do not require fasting and
can be done together.
Atherosclerosis Society/European Federation of Clinical Chemistry and
Laboratory Medicine (EAS/ EFLM) has proposed some recommendations regarding
measuring cholesterol levels. According to their joint consensus statement
published in the European Heart Journal:
- Fasting before a lipid test is not routinely required. Several studies indicate that lipid levels do not change much under most circumstances with normal food. However, a high-fat fast food meal may be avoided on the day of the testing to prevent high triglyceride levels.
- A minor decrease in LDL concentration has been noted when the levels were measured 1 to 3 hours following a meal. However, this decrease has also been noted when water is permitted during a fasting state due to dilution of blood. Therefore, the test can be done in the non-fasting state, but the patient should be asked to restrict water intake before the test.
- Measurement of triglycerides may be repeated in fasting state if the non-fasting plasma triglyceride concentration is more than 5 mmol/L (440 mg/dL). A fasting test may be necessary for those recovering from hypertriglyceridemic pancreatitis. Children may also require the test to be repeated in a fasting state to diagnose a lipid disorder that requires treatment.
- Very high levels require immediate referral for treatment.
American College of Cardiology/American Heart Association (ACC/AHA) guidelines
recommend fasting levels to calculate LDL cholesterol levels before starting
treatment with statins (drugs used to treat high cholesterol levels), or for
those with very high non-HDL cholesterol or triglyceride levels (non-HDL
cholesterol ≥5.7 mmol/L (220 mg/dL) or triglycerides ≥5.7 mmol/L (500 mg/dL)).
Fasting may not be required for screening for lipid disorders
but may be needed for coming to a specific diagnosis of the cause of abnormal lipids. The reference levels for lipids may differ in a non-fasting and fasting state. Therefore, discuss with your laboratory if you can come in the non-fasting state before going for the lipid profile test.
Nordestgaard et al. Fasting is not
routinely required for determination of a lipid profile: clinical and
laboratory implications including flagging at desirable concentration
cut-points-a joint consensus statement from the European Atherosclerosis
Society and European Federation of Clinical Chemistry and Laboratory Medicine.
European Heart Journal doi:10.1093/eurheartj/ehw152