What Are Triglycerides? High and Low Triglyceride Levels

Triglyceride is a fundamental type of blood fat obtained from the foods we consume during the day or synthesized through the body’s own mechanisms, enabling excess calories that cannot be used immediately to be stored for future energy expenditure. An increase in the amount of this fat in circulation above the expected standard limits is defined as high triglycerides, while a decrease to levels that cannot support the body’s basic fuel requirements is defined as low triglycerides. These lipid structures perform highly important functions for the continuity of the cellular cycle, the protection of organs from external factors, and the regulation of body temperature. In order to maintain general well-being and support vascular health, it is of great importance to keep the blood lipid profile balance within certain reference ranges.

What Are the Differences Between Triglycerides and Cholesterol?

Triglycerides and cholesterol, which we usually see side by side in blood test results, are two different structures in terms of their functions in the body, although they are frequently confused with one another among the public. The most basic function of triglycerides is to act as a fuel reserve to meet the body’s energy needs. When energy is needed during long periods of fasting, nighttime sleep, or intense physical exercise, special enzymes in the body come into play. These stores are broken down, enter the bloodstream, and provide the fuel required by the muscles.

Cholesterol, on the other hand, is more like a construction material for cells than an energy source. Maintaining the flexibility of cell membranes, producing bile acids necessary for digestion, and forming the foundation of vitamin D and certain important hormones are the functions of cholesterol. While a large portion of cholesterol is naturally produced in the body, triglyceride levels can change very rapidly depending on a person’s daily dietary routine, the amount of sweets consumed, and physical activity during the day. The liver tends to rapidly convert excess sugar in circulation into triglycerides and release them into the bloodstream. When the balance in this system is lost, the door is also opened to processes that threaten cardiovascular health.

What Causes High Triglycerides?

Health screenings conducted throughout the population reveal that a significant proportion of adults are at risk of high triglycerides. Among the most common underlying causes of this condition are the dietary mistakes and sedentary lifestyle brought about by the modern age. Excessive consumption of refined carbohydrates, pastries, and especially sugary syrups in processed foods during meals causes the liver to rapidly convert this excess energy into fat.

Of course, not only eating and drinking habits but also genetic predispositions or other health problems in the body may sometimes increase these values. Conditions that disrupt the functioning of the metabolism also directly affect the balance of blood fats. The main factors that may predispose to this condition are as follows:

• Obesity
• Insulin resistance
• Diabetes
• Sedentary lifestyle
• Hypothyroidism
• Kidney failure
• Genetic predisposition

What Are Ideal Triglyceride Levels and How Are They Measured?

For blood fats to be analyzed accurately, tests are generally expected to be performed after an overnight fast of eight to twelve hours. In blood samples taken after eating, triglyceride levels may temporarily appear high because the fats in recently consumed meals enter the bloodstream, and this may provide misleading information about the overall health condition.

For healthy vascular structure, a fasting triglyceride level below 150 mg/dL is considered ideal. These levels indicate that the inner surface of the vessels continues to function healthily and that risks are low. A level measured between 150 and 199 mg/dL is generally called “borderline high.” This range may be a warning sign of an emerging metabolic slowdown. At this stage, dietary regulation and increased physical activity are recommended rather than medication treatment.

Values between 200 and 499 mg/dL indicate the high-risk category. At these levels, fat accumulation in the vessel walls may accelerate. A level of 500 mg/dL or above is defined as severe elevation. Such high levels reflect a much more urgent condition that begins to seriously threaten internal organs as well as vascular health.

What Problems Does Severe High Triglyceride Cause in the Body?

Mild or moderate elevations in triglycerides are generally referred to as a “silent danger” because they can progress for years without causing any symptoms. The person may feel completely healthy. However, when values rise to very high levels, especially toward the 1000 mg/dL threshold, the excessive fat circulating in the blood disrupts the fluidity of the blood and causes it to become extremely dense. This dense blood may block the fine capillary vessels inside the pancreas and cause the tissue to become deprived of oxygen. Acute pancreatitis, known as the pancreas damaging its own tissue with the digestive enzymes it produces, is a severe condition that presents with intense stomach pain radiating to the back and requires emergency intervention.

Not only the pancreas, but excess fat circulating in the blood also begins to accumulate in internal organs. As the liver and spleen try to store these fats, they may become fatty and enlarge beyond their normal size. Fatty liver may pave the way for more advanced damage over time. In addition, the body may even try to store this fat under the skin. The physical signs that may be seen in the body when these high values are reached are as follows:

• Fatty liver
• Enlarged spleen
• Inflammation of the pancreas
• Yellow fatty deposits on the skin
• Plaques on the eyelids

Does Low Triglyceride (Hypotriglyceridemia) Always Indicate Good Health?

There is a widespread belief in society that having blood fats at the lowest possible level is always an indicator of perfect health. Triglyceride levels below 50 mg/dL are referred to as hypotriglyceridemia. If the person avoids sugar, exercises regularly, and follows a balanced diet, this low level is generally a sign of a well-functioning metabolism.

However, a level below 30 mg/dL may indicate that there is not enough energy in the body or that nutrients are not being absorbed properly. Insufficient calorie intake and digestive problems such as celiac disease that prevent the absorption of nutrients from food through the intestines may cause this condition. In addition, overactivity of the thyroid gland may cause the body to burn and consume all fat stores very rapidly. Some complaints related to cellular energy deficiency may be observed in people with such low fat levels. The findings that may occur due to depletion of the body’s energy stores are as follows:

• Chronic fatigue
• Constant feeling of cold
• Dry skin
• Hair breakage
• Loss of muscle mass
• Susceptibility to infections

How Does High Triglyceride Affect Cardiovascular Health?

The effects of high triglycerides on the cardiovascular system play a major role in the development of vascular blockages (atherosclerosis). The delicate lining called the endothelium that covers the inner surface of blood vessels gradually becomes permeable due to the wear caused by high fat levels. As a result of impaired triglyceride balance, dangerous cholesterol particles with a very small and dense structure begin to accumulate in the bloodstream. These particles pass through the damaged endothelial layer, infiltrate the vessel wall, and begin to accumulate there.

The body’s defense system perceives these fat particles that have infiltrated the vessel wall as foreign substances and sends cells to the area to remove them. However, while these defense cells try to engulf the fat in the vessel wall, they swell, become sluggish, and eventually die there, forming an inflamed fatty deposit, namely an atherosclerotic plaque.

The critical detail in vascular diseases is not how narrowed the vessel is, but how stable or fragile the plaque inside it is. Plaques with a thick and strong covering generally grow slowly and are more stable. However, a high-triglyceride environment predisposes to the formation of plaques inside the vessel that are filled with soft fat and have an extremely thin and fragile covering. When this thin membrane tears due to a sudden increase in blood pressure or the stress created by blood flow, the inflamed material inside the plaque comes into contact with the blood. The body forms a massive blood clot within seconds to repair this tear, and when this clot completely blocks the vessel, a heart attack occurs.

What Are the Deficiencies in Treatment Management in Heart Patients with Triglyceride-Related Disease?

When the treatment processes of individuals with a history of cardiovascular disease are examined, it is generally observed that while cholesterol values receive considerable attention, triglyceride levels may occasionally remain in the background. Certain observations conducted on patients admitted to hospitals with complaints of heart pain or vascular blockage show that there are areas in lipid management that need improvement.

For example, it is known that many patients with vascular blockage have low levels of good cholesterol (HDL) and high triglyceride values. Nevertheless, there may be situations in which preventive treatments aimed at balancing these values are not always emphasized strongly enough after discharge. Greater attention should be paid to the possibility that standard cholesterol medications alone may not be sufficient in patients with high triglycerides and that special diets and additional medical support may be required. Some management deficiencies encountered in treatment practice are as follows:

• Neglecting triglyceride measurements
• Disregarding borderline high values
• Failure to initiate target-oriented medication
• Insufficient lifestyle counseling
• Delays in treatment follow-up

Why May Conventional Angiography Be Insufficient in Triglyceride-Related Vascular Blockages?

Standard coronary angiography, which has been used for many years to detect vascular blockages, is the process of obtaining a two-dimensional image of the vessel by injecting a special contrast agent into it. This method generally shows how blood flows within the vessel and where it encounters obstruction. However, angiography has certain limitations due to its nature because it can only show the empty space inside the vessel and cannot clearly reveal the structure of the fleshy wall surrounding that space or how much fat is embedded within the wall.

Soft plaques that develop especially due to high triglycerides may sometimes grow outward from the vessel rather than inward into its lumen. In such cases, blood flow inside the vessel may appear completely normal on a conventional angiography screen. However, the vessel wall is filled with an inflamed fatty deposit that is highly prone to rupture. Advanced intravascular imaging systems are needed to visualize these hidden dangers more clearly, evaluate the internal structure of the tissue, and guide the planned intervention more accurately.

How Is Intravascular Ultrasound (IVUS) Used to Detect Triglyceride-Related Plaques?

Intravascular Ultrasound, commonly known by the abbreviation IVUS, is an advanced technology that enables the inner surface of the coronary arteries supplying the heart to be visualized at a 360-degree angle. This system works by placing a miniature version of the ultrasound devices commonly seen in hospitals, small enough to enter the vessel, at the tip of a very thin wire.

During the procedure, after preparations are made to prevent vascular spasms and thin the blood, the physician advances a very thin guidewire beyond the suspicious area in the vessel. The IVUS device is advanced over this wire and lowered deep into the vessel. Then an automatic pullback mechanism draws the device backward at a speed of approximately one millimeter per second while continuously obtaining cross-sectional images of the vessel wall.

Thanks to these cross-sections displayed on the screen, the layers of the vessel wall can be observed. IVUS also distinguishes the structure of plaques by examining the intensity of sound waves reflected from the tissues. If a dark and blackish area is seen on the screen, this region generally indicates a soft and fragile plaque filled with fat and associated with high triglycerides. Light-colored and bright reflections indicate hardened or calcified tissues. IVUS makes a major contribution to the treatment plan by showing where the problem is located and how deep it extends with a very high degree of accuracy.

Why Is Optical Coherence Tomography (OCT) Preferred in Triglyceride-Related Vascular Problems?

Optical Coherence Tomography (OCT) is a highly sensitive imaging method that uses near-infrared light waves instead of sound waves, although its operating principle is similar to IVUS technology. The level of detail OCT provides to medicine is considered equivalent to placing a microscope inside the vessel and examining tissues at the cellular level. Its image resolution is much higher than ultrasound.

The most distinctive feature of unstable plaques caused by high triglycerides is that the covering over the fatty deposit is extremely thin. Conventional methods may be insufficient to measure the thickness of this membrane. However, with the power of light waves, OCT can calculate the thickness of this extremely thin covering down to one-thousandth of a millimeter and detect the activity of cells weakening the membrane within the vessel wall. Because light is used, a liquid is injected into the vessel for a very short period at the moment of imaging to clear the blood that could distort the image, and hundreds of photographs are taken within that second to map the vessel structure in three dimensions. The advantages this unique technology brings to clinical practice are as follows:

• High-resolution imaging
• Measurement of the thin plaque covering
• Detection of inflammatory cells
• Three-dimensional structural mapping
• Analysis of the stent placement area

How Do Advanced Imaging Methods Improve Stent Treatments in Triglyceride Patients?

One of the most important goals in interventional cardiology applications is to ensure that the metallic support cages known as “stents,” which are placed inside narrowed vessels, perform their function without problems for many years. Vascular blockages that develop in the presence of high triglycerides generally display complex structures that are prone to clot formation. Therefore, drug-eluting stents, which help prevent the vessel from becoming blocked again to a great extent, are preferred today. However, how the stent is placed in the vessel is just as vital as the quality of the stent. Devices such as IVUS and OCT make this placement process much safer.

When intravascular imaging is not used, the diameter and length of the stent are estimated using two-dimensional images obtained from outside. If the selected stent is too small for the vessel, it cannot expand properly and may disrupt blood flow. If it is selected too large, it may overstress the vessel wall and cause tissue damage. In addition, when the stent is placed in the vessel, the metal wires must make firm contact with the vessel wall. If small gaps remain between the metal and the tissue, blood vortices form in these areas and may gradually clot, leading to sudden blockages. The details examined during stent optimization with imaging methods are as follows:

• The true width of the vessel
• The length of the diseased area
• Contact of the stent with the tissue
• Expansion of the metal struts
• Checking for tears in the vessel wall

Frequently Asked Questions

Prof. Dr. Kadriye Kılıçkesmez

Prof. Dr. Kadriye Orta Kılıçkesmez is one of the leading figures in the field of Turkish cardiology. She was born on January 24, 1974, in Tekirdağ. After completing her undergraduate education at Istanbul University Cerrahpaşa Faculty of Medicine, she chose cardiology as her specialty and received her specialist training at the Cardiology Institute of the same university. In 2015, she was appointed by the university to establish the Şişli Etfal cardiology clinic and Angio laboratory. Becoming a professor in 2017, Kadriye Kılıçkesmez established the cardiology clinic and Angio laboratory of Prof. Dr. Cemil Taşçı Hospital in 2020 and ensured that the clinic became a training clinic.