What are lipids? What is lipid profile testing?

Lipids, i.e. various fractions of cholesterol and triglycerides, are fatty substances necessary for the proper functioning of the human body. They are produced in the liver and delivered with food. Cholesterol is a building component of cell membranes, it is necessary for the productionof bile acids, steroid hormones and vitamin D₃, is involved in transmitting signals in the nervous system. In turn, triglycerides are e.g. a source of energy for tissues, especially muscles. Cholesterol and triglycerides in the body are found in free and protein-bound lipoproteins: HDL (high-density lipoproteins), LDL (low-density lipoproteins), VLDL (very low-density lipoproteins), IDL (intermediate-density lipoproteins) and chylomicrons. The problem is the elevated lipid concentration, well above the body’s needs. The assessment of the lipid profile, lipid panel or lipidogram is used to assess the body’s lipid metabolism. It includes:

• total cholesterol
• LDL cholesterol
• HDL cholesterol
• triglycerides.

In some cases, extended lipid profile tests are ordered, including VLDL cholesterol, non-HDL cholesterol, the number of LDL cholesterol particles or the total cholesterol / HDL ratio (Castelli index).

LDL cholesterol is commonly referred to as “bad” while HDL-C is “good”. This is due to their essential function. HDL primarily transports excess cholesterol from the body cells to the liver, where it can be processed and removed from the body, while protecting against the development ofatherosclerosis, and LDL delivers cholesterol to cells, depositing its excess, among others. in the walls of blood vessels, contributing to the development of atherosclerosis and its consequences. In fact, however, for proper functioning, both types of lipoproteins are required in the right concentration.

What are the indications for lipid testing?

Lipid parameters inform about the risk of developing ischemic heart disease as a result of coronary atherosclerosis. Total cholesterol determination as a screening or lipid profile test is recommended for all adults without risk factors forcoronary artery diseaseevery 5 years, starting around the age of 20 years. If you have an increased risk of heart disease, people who are on diet or drug therapy to lower their cholesterol are tested more often. The lipidogram is also performed in children and adolescents with risk factors for the development of atherosclerosis.

Risk factors for coronary heart disease in addition to high LDL cholesterol include:

• smoking
• age (over 45 for men, 55 for women)
• arterial hypertension(blood pressure above 140/90 mm Hg or taking antihypertensive drugs)
• family history of heart disease at an early age (before 55 years for men or before 65 years for women)
• diabetes
• previousheart attack
• overweight or obese
• HDL-C concentration below 40 mg / dL.

In addition, the indication for cholesterol and triglyceride testing is:

• history of family dyslipidemia
• chronic kidney disease
• chronic inflammatory diseases such asrheumatoid arthritis,systemic lupus erythematosus,psoriasis
• monitoring the effectiveness of dietary and pharmacological treatment of lipid disorders.

How is the test performed?

To perform the determination of the lipid profile, it is enough to collect a small amount of venous blood (most often from the ulnar vein), and in the case of rapid strip screening tests, only pricking the fingertip to obtain a drop of blood.

How to prepare for lipid testing?

In order to properly perform the lipid profile, it is necessary to fast 9-12 hours before the examination. Only drinking water is allowed. You should not consume alcohol in the 24 hours preceding the examination.

What are the contraindications for the study?

There are no contraindications for examining the lipid profile and its individual components.

Interpretation of the lipid profile test results

There are no strictly defined standards for lipid values ​​applicable to the general population. Lipid parameters should be assessed depending on the specific risk level of cardiovascular diseases and comorbidities such as diabetes mellitus.

Total cholesterol

According to the guidelines of the European Society of Cardiology, total cholesterol levels above 190 mg / dl (5 mmol / l) are considered abnormal.

HDL cholesterol

• normal in men: at least 40 mg / dl (1 mmol / l)
• normal in women: at least 45 mg / dl (1.2 mmol / l)

HDL cholesterol is much lower in smokers and increases in physically active people.

LDL cholesterol

• the norm in people without the burden of heart disease: below 115 mg / dl
• the norm in people with 1 risk factor, diabetes without organ complications: below 100 mg / dl
• the norm in people with cardiovascular disease, atherosclerosis of other arteries, after astroke, with diabetes with organ complications or chronic kidney disease: below 70 mg / dl

Triglycerides

• normal: below 150 mg / dl (1.7 mmol / l)

Reasons for increased values ​​of lipid parameters:

• incorrect diet and unhealthy lifestyle (lack of exercise, stimulants)
• overweight and obesity
• genetic predispositions
• metabolic diseases, e.g.hypothyroidism
• taking medications: corticosteroids, beta-blockers,estrogens(hormonal contraception)
• pregnancy.

Low blood lipids arenot a determinant of poor health (except for HDL cholesterol). The cause may behyperthyroidism, malnutrition, malabsorption syndrome orcirrhosis, and in the case of HDL cholesterol also smoking.