Lipoprotein:- Part 5 – Triglycerides (TG)
Sample for Triglycerides (TG)
- This is done ideally on the fasting serum of the patient. Venous blood is taken.
- Fasting for 12 to 14 hours is required.
- Plasma with EDTA can be used.
- The sample is stable at 4 °C for 7 days and at -20 °C for 3 months.
- If plasma is used, then multiply the result by 1.03.
Precautions for Triglycerides (TG)
- Patients must have at least fasting for 12 hours.
- 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.
- Intake of the fatty meal may increase the TG.
- Alcohol intake increases TG.
- In pregnancy, the TG level is raised.
- Take H/O drubs like oral contraceptives and estrogen to increase the TG level.
- Take H/O ascorbic acid, clofibrate, and colestipol to decrease the TG level.
Indications for Triglycerides (TG)
- This is done to evaluate the causes of atherosclerosis (Coronary artery disease).
- This is done to evaluate the turbid serum (milky).
- Triglyceride is part of the lipid profile.
- 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:
- Plants contain polyunsaturated fatty acids.
- The animal source contains mostly saturated fatty acids and solids at room temperature.
- Glucose must be present in the cells for the formation of TG.
- One of the sources gives the following ratio of triglycerides in various fats.
- TG consists of three fatty acids + one molecule of glycerol by ester bond, so-called Triglycerides.
- Glycerol and fatty acids are building blocks for TG.
- Three fatty acids + one molecule of glycerol (ester bond) = Triglyceride
- TG is present in the blood and transported by the VLDL and LDL.
- There is Triglyceride formation by the glycolytic pathway in glucose catabolism.
- This triglyceride formation may be absent in the case of:
- Uncontrolled diabetes mellitus.
- TG, when catabolized, forms a small fraction of free fatty acid, which appears in plasma bound to albumin.
- These nonesterified fatty acids, after oxidation, enter the Acetyl CoA cycle.
- The end result is water, CO2, and ATP, the energy source.
Storage of the Triglycerides (TG):
- Triglycerides (TG) are the fat in the bloodstream.
- Triglycerides (TG) account for more than 90 % of the food intake and are 95% of the fat stored.
- Triglycerides (TG) are insoluble in water; this is the main glycerol ester.
- TG is stored in adipose tissue as :
- Fatty acids.
- The liver is the factory to convert all the above into triglycerides.
- Triglycerides (TG) are Transported and present in :
- 80% are in VLDL.
- 15% are in LDL.
- TG is the source of energy.
- When TG is high then starts depositing in fatty tissue.
- 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.
- This can be completed by doing a lipid profile.
Normal Triglycerides (TG)
|Age||Male mg/dL||Female mg/dL|
|Cord blood||13 to 95||11 to 76|
|0 to 9 year||30 to 100||35 to 110|
|10 to 14 year||32 to 125||37 to 131|
|15 to 19 year||37 to 148||39 to 124|
|20 to 24 year||44 to 201||36 to 131|
|25 to 29 year||46 to 249||37 to 144|
|30 to 34 year||50 to 266||39 to 150|
|35 to 39 year||54 to 321||40 to 176|
|40 to 44 year||55 to 320||45 to 191|
|45 to 49 year||58 to 327||46 to 214|
|50 to 54 year||58 to 320||52 to 233|
|55 to 59 year||58 to 286||55 to 262|
|60 to 64 year||58 to 291||56 to 239|
|>65 year||55 to 260||60 to 240|
- 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
- Male Adult = 40 to 160 mg /dL.
- Female Adult = 35 to 135 mg /dL.
|Children||Male mg/dL||Female mg/dL|
|0 to 5 years||30 to 86||32 to 99|
|6 to 11 years||33 to 108||35 to 114|
|12 to 15 years||36 to 138||41 to 138|
|16 to 19 years||40 to 163||40 to 128 mg|
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).
|Risk factor||Serum Triglyceride mg/dL|
|Borderline||200 to 400|
|High||400 to 1000|
Increased Triglycerides values are seen in the following:
- Nephrotic syndrome.
- Liver diseases.
- Alcoholism (alcoholic cirrhosis).
- Diabetes Mellitus, uncontrolled.
- Glycogen storage disease (Von Gierke disease).
- Familial hypertriglyceridemia.
- Anorexia nervosa.
- Down’s syndrome.
- Myocardial infarction.
Decreased Triglycerides level is seen in:
- Congenital α-β- lipoproteinemia.
Management of Hypertriglyceridemia:
- If Triglycerides (TG) are < 200 mg/dL, then the person needs diet control, and he should be advised to repeat triglyceride once a year.
- If Triglycerides (TG) are 200 to 500 mg/dL, then evaluate the patient with risk factors like:
- Diabetes mellitus
- Medication like beta-blockers, Estrogen, corticosteroids, and oral contraceptives.
- Diseases like kidney and pancreatitis.
- No above risk factors in a person need only diet control
- Positive above risk factors and family history in a person needs diet and medication
- 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:
|Size (diameter nm)||>70.0||4 to 10||19.6 to 22.7||25 to 70|
|Electrophoretic mobility||Origin||α – region||β – region||Pre – β region|
|Molecular weight||0.4 to 30 x 109||3.6 x 109||2.75 x 109||5 to 10 x 109|
|Synthesized in||Intestine||Intestine and liver||Intravascular||Liver and intestine|
|Composition by weight in %|
|Cholesterol esterified||5||38||49||11 to 14|
|Cholesterol unesterified||2||10||13||5 to 8|
|Triglycerides||84||9||11||44 to 60|
|Phospholipids||7||22||27||20 to 23|
|Proteins||2||21||23||4 to 11|
Questions and answers:
Question 1: What is the critical value of the triglycerides?
Critical value of the triglycerides is >500 mg/dL.
Question 2: What is the role of VLDL in case of triglycerides?
VLDL carries triglycerides 80% of its portion.