What is dyslipidaemia?

Dyslipidaemia is associated with unhealthy lipid levels, called cholesterol, in your bloodstream. To put it simply, cholesterol is the fat that flows through your blood, and when these levels get too high, it puts your heart and blood vessels at risk. Excess cholesterol sticks to the vessel walls, forming fatty deposits that can narrow the vessels and make it harder for the heart to receive the oxygen-rich blood. This can lead to cardiovascular diseases.¹ Both cholesterol and triglycerides are absorbed and transported throughout the body when they are wrapped up with proteins to form an end product known as lipoproteins. The lipids are essential components of our body; they are mainly used to produce energy, synthesise steroids, and form bile acids.^1,2

Understanding lipid panels

A lipid panel is the essential blood test used primarily for diagnosing dyslipidaemia and monitoring the effectiveness of medicines in treating and preventing this condition.¹ It includes various components that help provide an overview of your blood fat levels.

1. Total cholesterol (TC): this contains the total cholesterol from all lipoproteins, including low-density lipoprotein (LDL), high-density lipoprotein (HDL), very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), lipoprotein (a) [LP(a)], and chylomicrons. It is a key element used by the doctors to combine it with other values to measure your non-HDL-C, LDL-D, and the total cholesterol/HDL-C ratio⁴
2. Triglycerides (TG): a type of fat derived from two main sources: fats your liver has made (VLDL and IDL) and the fats that come directly from the food you have eaten (chylomicrons)^1,2
3. High-density lipoprotein cholesterol (HDL-C): often addressed as “good” cholesterol. It is responsible for transporting nearly 25% of the cholesterol and clearing out the excess from the blood, thereby protecting your arteries against plaque formation^1,3
4. Low-density lipoprotein cholesterol (LDL-C): recognised as “bad cholesterol” due to its potential to clog arteries, which may further lead to decreased blood supply to the heart^1,2 
5. Non-HDL cholesterol (non-HDL-C): this is generally used to evaluate the risk of cardiovascular diseases and can be measured by subtracting HDL-C from TC^3,6

According to current guidelines, the fasting samples are not required for routine testing, except when the non-fasting triglyceride levels are ≥ 400 mg/dL (4.5 mmol/L) or when there is a known history of raised TGs (hypertriglyceridaemia). ^3,5,6

Screening guidelines

Routine analysis of lipid levels in dyslipidaemia is mandatory, especially when there is a family history or other risk factors involved.

Adults

As per the NCEP (ATP III) guidelines, a fasting lipid panel should be done every 5 years for people older than 20 years, whereas the AHA/ACC recommends testing every 4 to 6 years for patients between 40 and 75 years. Other guidelines advise a fasting lipid panel every 5 years for all adults between the ages of 20 and 78.¹

Children and adolescents

The American Academy of Paediatrics suggests routine assessment of lipid profile for all children between ages 9-11 years and 17-21 years, regardless of risk factors. For children aged 2-8 years and 12-16 years, lipid analysis is recommended when they have a family history of dyslipidaemia or other heart problems, or risk factors such as overweight, elevated blood sugar, high blood pressure, or exposure to smoking.¹

Routine lipid panel

These ranges are widely used as a starting point to understand your lipid panel results. The ideal lipid levels can be established depending upon your age, gender, and overall health status.¹ 

Note: divide by 38.67 for the conversion of cholesterol (mg/dl to mmol/l) and by 88.57 for the conversion (mg/dl to mmol/l).

What causes dyslipidaemia 

Several different factors can contribute to the development of dyslipidaemia, including family history, lifestyle choices such as diet and (lack of) exercise, and other environmental factors. It is categorised into two main types, depending on the root cause.

Primary dyslipidaemia

This happens due to variations in the genes that may result in high or low levels of lipid-carrying proteins and the lipids in the blood.¹

• Familial Hypercholesterolaemia: where the uptake of LDL-C is impaired due to its defective receptor gene. This condition is estimated to occur in about 1 in 500 individuals¹
• Familial Hypertriglyceridemia: changes in the LPL gene interfere with the breakdown of triglycerides, resulting in high levels of…. This happens in 1 in 500 of the general population¹
• Familial combined hyperlipidaemia: occurs due to too much cholesterol and triglyceride levels, due to the overproduction of VLDL and LDL by the liver. This happens in 1 in every 100 people¹
• Familial dysbetallipoproteinemia: disruption in the apo E gene activity, responsible for clearing fatty remnants from the blood, leads to both high cholesterol and triglycerides. It only affects 1 in 10000 individuals worldwide¹

Secondary dyslipidaemia

This is often reversible and is brought on by altered lipid levels from lifestyle factors or other medical conditions.¹ The following secondary causes may further worsen the primary dyslipidaemia.⁷

• Dietary factors: Consuming too much saturated and trans fats, eating cholesterol-containing foods, and not having enough fruits, nuts/seeds, and vegetables^1,2
• Physical inactivity and obesity: Lack of physical activity and increased weight gain enhance VLDL synthesis and reduce fat clearance by the liver^1,2
• Diabetes mellitus (high blood sugar): Spike in blood sugar levels and insulin resistance affects the body’s absorption of fats and cholesterol^1,2
• Hypothyroidism: Associated with impaired expression of LDL receptors and an enzyme (lipoprotein lipase) that degrades fats in the human body^1,7
• Chronic kidney disease: Slows down the breakdown of fat-carrying particles (apo B-containing lipoproteins) in your blood and reduces the activity of key enzymes (lipoprotein lipase and hepatic lipase) that help in clearing fats from the circulation^1,2
• Liver disease: Affects the formation and storage of fat-carrying proteins and bile acids, thereby impairing the transport and excretion of lipids^1,2
• Alcohol abuse: Increases the production of VLDL and decreases the conversion of fats into energy by the liver ^1,2
• Smoking: promotes cell damage and immune system overactivity, causing impaired formation of HDL-C and resulting in reduced HDL-C levels^1,2
• Certain medications: Such as atypical antipsychotics, steroids, and cyclosporin, can adversely impact the lipid panel. ^4,7

Clinical utility in diagnosis

A doctor diagnoses dyslipidaemia after carefully assessing your lipid panel results and decides whether the abnormal levels require treatment based on your risk factors and overall health status. There can be several changes in the lipid panel, including elevated “bad” cholesterol (LDL), increased triglycerides, and high non-HDL cholesterol. The decreased levels of “good” cholesterol (HDL) can also be an indicator of dyslipidaemia. Most of the time, the imbalance in lipid components occurs simultaneously, thereby further damaging your heart health.⁷ 

Risk assessment

Available evidence-based guidelines and easy-to-use online calculators made it helpful for predicting your chances of developing heart problems over the next ten years or even throughout your lifetime.⁷ Even when other factors are controlled, elevated bad cholesterol levels serve as an independent predictor of heart abnormalities.⁵

Guiding treatment

The need for treatment is based on the risk of developing other medical conditions due to the unusual lipid levels in your blood. The initial step in managing dyslipidaemia is lifestyle modification, and if this alone isn’t sufficient, then your doctor may also advise some medications. Lowering your LDL cholesterol levels will not only improve your heart health but also prevent further complications; hence, it is always the first target in treating dyslipidaemia. Once your “bad” cholesterol reaches the target level, then the next goal is to remove the other harmful particles, such as apolipoprotein B-containing lipoproteins, which are the carriers of cholesterol.⁷ 

Monitoring and follow-up

Frequent monitoring of lipid parameters is recommended, especially before and during the treatment, to evaluate the effectiveness and adjustment of medications. 

When to check your lipid levels?

• Baseline: always check your lipid levels twice before starting cholesterol-lowering medications^4,6
• After treatment initiation or change: repeat the blood tests after 2-3 months of starting or change of treatment^4,6
• Post-acute cardiovascular event: after surviving a heart attack, stroke, or mini stroke, the lipid panel should be delayed for 3 to 8 weeks⁴
• Stable on treatment: yearly monitoring is recommended once the cholesterol levels have stabilised with ongoing medications.⁴ For people with very low LDL cholesterol and a low risk of heart disease, testing every 5 years may be enough⁶  
• Severe Hypertriglyceridemia: if your triglyceride levels become dangerously high (>20.0 mmol/L), daily or alternate-day testing may be recommended. In case these levels increase further (10-20.0 mmol/L), weekly monitoring is often sufficient⁴ 

While LDL (bad cholesterol) remains the main target for cholesterol-lowering treatment, since 2021, there has been growing recognition of non-HDL cholesterol in assessing risk for unstable heart conditions.^3,4

Factors influencing testing frequency

Biological variation

Your cholesterol levels naturally fluctuate in day-to-day life (TC by 5-10% and TG by over 20%). These changes are influenced by lifestyle factors such as physical activity, dietary changes, smoking habits, and alcohol consumption.^3,4 Therefore, multiple lipid panels are recommended before making treatment decisions.⁴

Pregnancy

During the second and third trimesters of pregnancy, you may notice an increase in TC, triglycerides, and LDL-C, which is completely normal; hence, cholesterol testing should be avoided in this stage. Instead, consider retesting after 3 months of delivery.⁴

Acute phase response

Assess your lipid profile after 2 to 4 weeks of the active phase of illness, as it may produce altered cholesterol and triglyceride levels.⁴

Age and race

Among adults over 75 years of age and African American individuals, lipid levels are monitored less frequently.⁸

Insurance status

People with Medicaid insurance may also have less frequent lipid monitoring due to coverage limitations.⁸

Summary

Dyslipidaemia develops from too much cholesterol and fat in the bloodstream. When cholesterol and triglycerides combine with proteins, they form lipoproteins – particles that get these lipids absorbed and reach throughout the body. Unhealthy lipid levels arise from family history, lifestyle choices and environmental factors. In the majority of cases, dyslipidaemia can be managed by incorporating a healthy lifestyle. 

The application of lipid panels in confirming and monitoring dyslipidaemia depends on the initial assessment, individual risk factors, and associated health conditions. The first step is to assess for abnormalities, including increased low-density lipoprotein (LDL) cholesterol, elevated triglycerides (TG), non-high-density lipoprotein (non-HDL) cholesterol and high lipoprotein(a), along with decreased high-density lipoprotein (HDL) cholesterol. These unusual changes in lipid components often coexist together. Fasting samples are only necessary when non-fasting triglyceride levels are extremely high or when there is a known family history of hypertriglyceridaemia. It is essential to monitor these levels before, during and after the start of the treatment to adjust therapy and determine its effectiveness. Changes in lipid levels could be due to several reasons, such as pregnancy, normal daily body changes, active phases of illness, etc. Hence, the doctor’s decision to start treatment is always based on individual needs. People with long-standing conditions such as diabetes or a history of heart disease may need more frequent monitoring than healthy individuals, as the ultimate goal in treating imbalanced lipid levels is to support long-term heart health by protecting against heart problems and other related complications.