TRIACYLGLYCEROLS (TRIGLYCERIDES)
Information about test and interpretation about Result
1. Purpose:
Quantitative estimation of triacylglycerols in human serum by enzymatic method using Glycerol -3 Phosphate Oxidase (GPO) Measurement of triglycerides in conjunction with other lipid assays is used in screening the lipid status of an individual to detect atherosclerotic risks and in monitoring the response to lipid lowering measures triglyceride determinations when performed are useful in the diagnosis of primary and secondary hyperlipoproteinemia. They are also of interest in following the course of diabetes mellitus, nephrotic syndrome, biliary obstruction and various metabolic abnormalities due to endocrine disturbances.
2. Principle:
The procedure involves hydrolysis of triglycerides by lipoprotein lipase. The glycerol concentration is then determined by enzymatic assay coupled with Trinder reaction that terminates in the formation of a quinoneimine dye which is generated from 4-aminoantipyrine and 4-chlorophenol by hydrogen peroxide under the catalytic action of peroxidase. The amount of the dye formed, determined by its absorption at 500 nm, is directly proportional to the concentration of triglycerides in the sample.
3.1. Linearity: Up to 1000 mg/dL of serum
3.2. Measurement range: 1–1000 mg/dL of cholesterol in serum
3.3. Sensitivity: The minimum detection limit by this kit is 1 mg/dL.
4. Primary sample:
4.1. Use only fasting serum as specimen
4.2. Collect blood sample after an overnight fast of 12–14 hours when testing is a part of lipid profile
4.3. Collect 4 mL of venous blood in a plain vacutainer tube.
4.4. Allow the tube to stand for 30 minutes and separate the serum by centrifugation at 2500–3000 rpm for 5–10 minutes
4.5. Do not use lysed serum for testing as it may give very high results
4.6. Do not use contaminated/turbid samples for testing
4.7. Process the sample on the same day within 3 hours of collection.
4.8. If analysis is not done on the same day/within 3 hours of collection, separate the serum and store it at 20–25 °C for up to 2 days or at 4–8 °C for up to 7 days
5. Type of container and additive:
Use plain vacutainer tubes for collecting samples. No additive/preservative is needed to be added.
6. Reagents/Consumables:
Lipoprotein lipase, magnesium acetate, 4 aminoantipyrine, glycerol-3-phosphate oxidase, glycerol kinase, peroxidase, triglyceride standard 200 mg/dL triglycerides as triolein.
7. Instrument: Semi-autoanalyzer.
8. Procedure:
8.1. Switch on the machine and press “FLUSH “button by keeping the tubing in a container with 2% detergent for 2 minutes followed by distilled water for 2 minutes.
8.2. Press “PROC”. Different test procedures will be displayed.
8.3. Select the test to be processed by entering its number and then press “ENTER” key.
8.4. Now the assay parameters of the specific test procedure will be displayed. Note down the volume of the reagent and the sample to be used.
8.5. Feed the reagent blank with each batch of patient samples and ensure the absorbance of the blank is less than 0.300 at 520 nm if the absorbance of the ‘blank is more than 0.300, discard the reagent.
8.6. Then feed the test samples and record the values.
8.7. Check whether the sample is hemolyzed, icteric before processing. If the sample is lysed, collect another sample and proceed. If it is icteric or highly lipemic, dilute the sample 1 in 10 with distilled water and proceed. Multiply the result displayed by dilution factor 10.
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Assay: End point.
Reagent volume: 1000 μL
Wavelength: 546 nm
Sample volume: 10 μL
Temperature: 30°C
Zero setting with distilled water
Incubation time: 5 minutes
Conc. of standard: 200 mg/dL
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9. Calculating results:
Male: 60–165 mg/dL
Female: 40–140 mg/dL
11. Critical/Alert level values: 400 mg/dL
12. Laboratory interpretation: Triacylglycerolemia is a risk factor for myocardial infarction.
TGA is phenomenally increased in an eye disease lipemic retinalis.
13. Potential sources of variability:
13.1. Lysed serum specimens may give falsely elevated values
13.2. Do not use if the reagent is turbid as it indicates contamination of the reagent and if the absorbance of the blank reagent is more than 0.300.
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BIBLIOGRAPHY:
1. Annoni G, Bottasso BM. Ciaci D, Donato MF Tripoli A, Lab JJ. Res Lab Med 1982;9:115.
2. Buccolo G, David M. Clin. Chem 1973;19:476.
3. Werner M, Gabrielson DG, Estman G. Clin Chem 1981;21:268.
Reference: Manual of Medical Laboratory Techniques
Produce by: laboratorist
Dr. Yousef Al Adbai
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