Misleading Triglyceride Elevation in a Newborn

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A term neonate was admitted to the neonatal intensive care unit 1 hour after caesarian delivery for respiratory distress and neonatal hypoxia-ischemia. He was nonreactive exhibiting axial and peripheral hypotonia, without archaic reflexes. Glucose, electrolytes, and liver function tests were within reference limits (Table 1). Hypertriglyceridemia was reported despite a clear, nonlipemic serum. He was treated for 5 days with Monogen (Nutricia North America), a specific milk protein-based powder low in fat and long chain triglycerides, and high in medium-chain triglycerides. ... ... Hypertriglyceridemia in the newborn is due to genetic factors (e.g., familial hypertriglyceridemia caused by an excess of very low-density lipoprotein particles or familial chylomicronemia). It is associated with a lifetime risk of cardiovascular disease and pancreatitis (1, 2). Triglycerides constitute an important energy reserve. Dietary triglycerides are present in chylomicrons while liver-derived triglycerides are found in very low-density lipoprotein (2). As hypertriglyceridemia is typically associated with a lipemic serum, pseudohypertriglyceridemia must be suspected when hypertriglyceridemia is reported with nonlipemic serum. False elevation of serum triglycerides occurs due to the measurement of plasma glycerol by laboratory triglyceride enzymatic assay (3). Triglycerides, also known as triacylglycerols, are glycerides in which the 3 hydroxyl groups of glycerol are esterified with fatty acids. Automated laboratory assays commonly assess serum triglycerides using a colorimetric enzymatic assay. Triglycerides are hydrolyzed by microbial lipase into fatty acids and glycerol, which is then measured by a colorimetric reaction. Triglyceride concentration is calculated from the glycerol concentration (1, 3). Thus, in the case of elevated glycerol levels, an overestimation of serum triglycerides occurs (1, 3). The diagnosis of pseudohypertriglyceridemia avoids unnecessary treatment, as was the case for this newborn who was supplemented for 5 days with Monogen. This specific milk was used because short-chain triglycerides and medium-chain triglycerides are not involved in chylomicron formation and undergo rapid hepatic oxidation, so they do not increase blood triglycerides. Pseudohypertriglyceridemia also occurs in adults and must be suspected when a discrepancy between biochemical results and the patient’s and/or family history is observed, or when patients do not respond to triglyceride-lowering drugs or lifestyle measures (1, 4). A study has reported the following patient characteristics: predominantly male gender, nonobese, hypertriglyceridemia unresponsive to treatment, and lipid assessment characterized by low total cholesterol values (4).

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