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Test 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

Reporting Name

Glycerol Corrected Triglycerides, S

Specimen Type

Serum


Specimen Required


Patient Preparation:

1. Fasting-overnight (12-14 hours)

2. Patient must not consume any alcohol for 24 hours before the specimen is drawn

Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 0.5 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2 Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.


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

Interpretation

Patients with glycerol kinase deficiency typically have serum free glycerol concentrations greater than 10 fold above normal.

Clinical Reference

1. Tietz Textbook of Clinical Chemistry. Fifth edition. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 2001

2. Stinshoff K, Weisshaar D, Staehler F, et al: Relation between concentrations of free glycerol and triglycerides in human sera. Clin Chem 1977 Jun;23(6):1029-1032

3. Sjarif DR, Ploos van Amstel JK, Duran M, et al: Isolated and contiguous glycerol kinase gene disorders: a review. J Inherit Metab Dis 2000 Sep;23(6):529-547

4. Jacobson TA, Ito MK, Maki KC, et al: National Lipid Association recommendations for patient-centered management of dyslipidemia: part 1 - executive summary. J Clin Lipidol 2014 Sep-Oct;8(5):473-488

5. Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents; National Heart, Lung, and Blood Institute: Expert panel on integrated guidelines for cardiovascular health and risk reduction in children and adolescents. Pediatrics 2011 Dec;128 Suppl 5:S213-S256

Day(s) and Time(s) Performed

Monday through Saturday; Continuously

Analytic Time

Same day/1 day (not reported on Sunday)

CPT Code Information

84478

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TGGB Glycerol Corrected Triglycerides, S In Process

 

Result ID Test Result Name Result LOINC Value
TGCD2 Total Triglycerides, CDC, S 2571-8
TRIGB Corrected Triglyceride No LOINC Needed
GLYCL Glycerol, Calculated 45300-1

Method Name

Enzymatic Colorimetric

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).

Mayo Medical Laboratories | Cardiology Catalog Additional Information:

mml-lipids-lipoproteins