Pseudohypertriglyceridemia
Most triglyceride tests used in clinical laboratories do not measure triglyceride itself, but the glycerol hydrolyzed from triglyceride by lipase. Increased free glycerol in a sample will falsely increase the triglyceride measurement unless a blank is included in the reagent. According to the College of American Pathologists, only 7% of clinical laboratories enrolled in their proficiency testing for triglycerides use a glycerol-blanked method. Interference by high concentrations of free glycerol should be considered in patients with high triglyceride concentrations who do not respond to treatment and in samples without visible lipemia.
Glycerol kinase deficiency (GKD) is the most commonly reported cause of increased glycerol concentrations in patients. GKD is a rare X-linked recessive disorder affecting fewer than 200,000 individuals in the United States. It can occur as an isolated entity or combined with adrenal dysfunction or Duchenne muscular dystrophy. The clinical presentation of GKD ranges from asymptomatic to critical metabolic crisis. GKD is identified in patients with chronic hypertriglyceridemia, usually <1000 mg/dL, which does not respond to intensive exercise, dietary modifications, and triglyceride-lowering medications.
| Endogenous Glycerol | Exogenous Glycerol |
| Glycerol Kinase Deficiency | Glycerol ingestion |
| Alcoholism | Some alcoholic beverages |
| Hyperthyroidism | Glycerol containing medications (propofol) |
| Severe liver disease | Detergents & beauty produces |
Glycerol may also be increased by ingestion or use of glycerol-containing products. Glycerol is present in certain alcoholic beverages, medications, parenteral nutrition, beauty products, and cleaning products. Careful medical history and medication intake is necessary to identify exogeneous causes of hyperglycerolemia. Hypertriglyceridemia will disappear after cessation of these products.
Many physicians are unaware that the enzymatic methods used to measure triglycerides in most clinical laboratories may produce falsely increased results when glycerol is present. Failure of the laboratory to recognize pseudohypertriglyceridemia can lead to misdiagnosis and treatment of patients who are suspected of having a primary lipoprotein disorder.
References
Backes JM, et al. . Identifying pseudohypertriglyceridemia in clinical practice. Clin Lipidol 2014;9:625–41.
Farooq A et al. A woman with pancreatitis and hypertriglyceridemia. Clin Chem 2019;65:1216-20.
