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HelpTest ID TGGB Glycerol-Corrected Triglycerides, Serum
Useful For
Evaluation of pseudohypertriglyceridemia for possible glycerol kinase deficiency
Evaluation of triglyceride as a cardiovascular risk factor in individuals with elevated cholesterol values
Special Instructions
Method Name
Enzymatic Colorimetric
Reporting Name
Glycerol Corrected Triglycerides, SSpecimen Type
SerumContainer/Tube:
Preferred: Red top
Acceptable: Serum gel
Specimen Volume: 0.5 mL
Collection Instructions:
1. Fasting-overnight (12-14 hours)
2. Patient must not consume any alcohol for 24 hours before the specimen is drawn.
3. Serum gel tubes should be centrifuged within 2 hours of collection.
4. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.
Forms: If not ordering electronically, complete, print, and send a Cardiovascular Test Request Form (T724) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/cardiovascular-request-form.pdf).
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Frozen | 60 days | |
| Ambient | 24 hours |
Clinical Information
Triglycerides are esters of glycerol with 3 long-chain fatty acids. Increased plasma triglyceride concentrations are indicative of a metabolic abnormality and, along with elevated cholesterol, are considered a risk factor for atherosclerotic disease. Hyperlipidemia may be inherited or associated with biliary obstruction, diabetes mellitus, nephrotic syndrome, renal failure, or metabolic disorders related to endocrinopathies. Increased triglycerides may also be medication-induced (eg, prednisone). See Lipids and Lipoproteins in Blood Plasma in Special Instructions.
Traditional, nonglycerol-blanked methods for measuring triglycerides break down plasma and serum triglycerides into glycerol and fatty acids. The glycerol is then measured in an enzymatic colorimetric assay. Consequently, patients with elevated free glycerol in circulation will have a falsely elevated triglyceride concentration, pseudohypertriglyceridemia, when using a nonglycerol-blanked triglyceride assay.
Glycerol is an intermediate in the conversion of glucose to lipids and serves as the precursor for triglyceride and other glycerolipids. Patients with type 2 diabetes mellitus, hyperthyroidism, those who are obese, or those receiving oral or parenteral supplementation with glycerol may have slightly higher free glycerol in circulation, however this increase is unlikely to affect triglyceride result interpretation.
Glycerol kinase deficiency (GKD) is an X-linked genetic condition leading to impaired function of glycerol kinase (GK), the primary regulator of glycerol entry into metabolic pathways. Insufficient GK activity leads to extreme elevations in plasma glycerol concentrations (ie, hyperglycerolemia) and glyceroluria. Patients with GKD may be placed on a glycerol-restricted diet and instructed to avoid prolonged periods of fasting.
GKD is divided into 3 clinical forms:
-Complex GKD involves mutations in the GK locus and 2 others (adrenal hypoplasia congenital: AHC and Duchenne muscular dystrophy: DMD) on Xp21 and manifests in infants.
-Juvenile GKD is associated with metabolic and central nervous system instability and deterioration. Juvenile GKD usually presents in the early years of life as repeated vomiting, acidemia, and central nervous system depression.
- Adult GKD is mainly benign with detection usually found incidentally by pseudohypertriglyceridemia.
Reference Values
TRIGLYCERIDE, TOTAL and CORRECTED
The National Cholesterol Education Program (NCEP) has set the following guidelines in adults ages 18 and up:
Normal: <150 mg/dL
Borderline high: 150-199 mg/dL
High: 200-499 mg/dL
Very high: ≥500 mg/dL
The National Cholesterol Education Program (NCEP) and National Health and Nutrition Examination Survey (NHANES) has set the following guidelines in children ages <2:
<2 years: Reference values have not been established for patients who are <24 months of age.
2-9 years:
Acceptable: <75 mg/dL
Borderline high: 75-99 mg/dL
High: ≥100 mg/dL
10-17 years:
Normal: <90 mg/dL
Borderline high: 90-129 mg/dL
High: ≥130 mg/dL
GLYCEROL, CALCULATED
<18 years: Reference values have not been established for patients who are <18 years of age.
>18 years: 40-370 mcmol/L
Cautions
Patients should be fasting.
Exogenous sources of glycerol will interfere with assay results.
Result can be falsely decreased in patients with elevated levels of N-acetyl-p-benzoquinone imine (NAPQI)-a metabolite of acetaminophen, N-acetylcysteine (NAC), and metamizole.
Day(s) Performed
Monday through Saturday; Continuously
Report Available
Same day/1 day (not reported on Sunday)Performing Laboratory
Mayo Medical Laboratories in Rochester
CPT Code Information
84478