Triglycerides (TG)

Sample for Triglycerides (TG)

1. This is done ideally on the fasting serum of the patient. Venous blood is taken.
2. Fasting for 12 to 14 hours is required.
3. Plasma with EDTA can be used.
4. The sample is stable at 4 °C for 7 days and at -20 °C for 3 months.
5. If plasma is used, then multiply the result by 1.03.

Precautions for Triglycerides (TG)

1. Patients must have at least fasting for 12 hours.
2. If  TG in males> 160  mg/dL and females> 135 mg/dL, then two more samples should be done in the next 6 to 8 weeks.
3. Intake of the fatty meal may increase the TG.
4. Alcohol intake increases TG.
5. In pregnancy, the TG level is raised.
6. Take H/O drubs like oral contraceptives and estrogen to increase the TG level.
7. Take H/O ascorbic acid, clofibrate, and colestipol to decrease the TG level.

Indications for Triglycerides (TG)

1. This is done to evaluate the causes of atherosclerosis (Coronary artery disease).
2. This is done to evaluate the turbid serum (milky).
3. Triglyceride is part of the lipid profile.
4. Triglyceride is advised in a patient with a suspected fat metabolism disorder.

Definition of Triglyceride (TG)

• Triglyceride (TG) is primarily found in chylomicrons and VLDL.
• Triglyceride (TG)  provides a good estimate of VLDL.
• Triglycerides are good risk factors for coronary heart disease is controversial.

Pathophysiology of Triglycerides (TG)                                                                                                                                   

Source of Triglyceride:

1. Plants contain polyunsaturated fatty acids.
   1. Corn.
   2. Sunflower.
   3. Safflower.
2. The animal source contains mostly saturated fatty acids and solids at room temperature.
3. Glucose must be present in the cells for the formation of TG.
4. One of the sources gives the following ratio of triglycerides in various fats.

Triglycerides (TG) composition

Triglyceride structure:

1. TG consists of three fatty acids + one molecule of glycerol by ester bond, so-called Triglycerides.
2.  Glycerol and fatty acids are building blocks for TG.
   1. Three fatty acids  + one molecule of glycerol (ester bond)  =  Triglyceride
3. TG is present in the blood and transported by the VLDL and LDL.

4. There is Triglyceride formation by the glycolytic pathway in glucose catabolism.
5. This triglyceride formation may be absent in the case of:
   1. Fasting.
   2. Starvation.
   3. Uncontrolled diabetes mellitus.

Triglyceride catabolism:

1. TG, when catabolized, forms a small fraction of free fatty acid, which appears in plasma bound to albumin.
2. These nonesterified fatty acids, after oxidation, enter the Acetyl CoA cycle.
3. The end result is water, CO2, and ATP, the energy source.

Storage of the Triglycerides (TG):

1. Triglycerides (TG) are the fat in the bloodstream.
2. Triglycerides (TG) account for more than 90 % of the food intake and are 95% of the fat stored.
3. Triglycerides (TG) are insoluble in water; this is the main glycerol ester.
4. TG is stored in adipose tissue as :
   1. Glycerol.
   2. Fatty acids.
   3. Monoglyceride.
5. The liver is the factory to convert all the above into triglycerides.

6. Triglycerides (TG) are Transported and present in :
   1. 80% are in VLDL.
   2. 15% are in LDL.

7. TG is the source of energy.
8. When TG is high then starts depositing in fatty tissue.
9. The Fredrickson-levy classification method for hyperlipidemia:  Keep the plasma at 4 °C refrigerate for 16 hours, and then made an observation of the creamy layer at the top of turbidity.
   1. This can be completed by doing a lipid profile.

Normal Triglycerides (TG)

Source 1

• To convert into SI unit x 0.0113 = mmol/L
• Recommended cutoff point for evaluating triglyceridemia status:
  • Normal = <250 mg/dL
  • Borderline high = 250 to 500 mg/dL
  • Hypertriglyceridemic = >500 mg/dL
  • High risk for pancreatitis = >1000 mg/dL

Source 2

• Male Adult  = 40 to 160 mg /dL.
• Female Adult  = 35 to 135 mg /dL.

Critical values of triglycerides are:

• Desirable = < 150 mg /dL.
• Borderline high = 150 to 199 mg /dL.
• High = 200 to 499 mg /dL.
• Very high = > 500 mg /dL.
• Critical value  >400 mg/dL

Triglycerides (TG) concentration, according to the National cholesterol education program:

(Adult treatment panel (NECP-ATP II).

Increased Triglycerides values are seen in the following:

1. Hyperlipidemia.
2. Hyperlipoproteinemia.
3. Nephrotic syndrome.
4. Liver diseases.
5. Alcoholism (alcoholic cirrhosis).
6. Diabetes Mellitus, uncontrolled.
7. Glycogen storage disease (Von Gierke disease).
8. Familial hypertriglyceridemia.
9. Hypothyroidism.
10. Gout.
11. Anorexia nervosa.
12. Down’s syndrome.
13. Myocardial infarction.

Decreased Triglycerides level is seen in:

1. Malnutrition.
2. Hyperthyroidism.
3. Congenital α-β- lipoproteinemia.
4. Malabsorption.

Management of Hypertriglyceridemia:

1. If Triglycerides (TG) are < 200 mg/dL, then the person needs diet control, and he should be advised to repeat triglyceride once a year.
2. If Triglycerides (TG) are 200 to 500 mg/dL, then evaluate the patient with risk factors like:
   1. Diabetes mellitus
   2. Alcoholism
   3. Hypothyroidism
   4. Hypertension
   5. Hyperuricemia
   6. Medication like beta-blockers, Estrogen, corticosteroids, and oral contraceptives.
   7. Diseases like kidney and pancreatitis.
      1. No above risk factors in a person need only diet control
      2. Positive above risk factors and family history in a person needs diet and medication

Critical value:

• If a person’s triglyceride is >500 mg/dL, then these patients need diet control and medication.

Table showing the summary of characteristics of the lipoproteins:

Questions and answers: