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TG

Triglycerides: desirable levels, fasting vs non-fasting tests, causes of hypertriglyceridaemia, cardiovascular and pancreatitis risk.

Triglycerides (TG) are the main form in which the body stores and transports fat for energy. They come from food (carried by chylomicrons) and are made in the liver from excess calories, sugar and alcohol (carried by VLDL). Moderately raised triglycerides indicate an excess of triglyceride-rich, cholesterol-containing remnant particles that promote atherosclerosis. Very high levels (above 10 mmol/L) carry a risk of acute pancreatitis.

Lipid profileMetabolic syndromePancreatitis

Desirable (fasting)< 1.7 mmol/L (< 150 mg/dL)

Non-fasting, acceptable< 2.0 mmol/L (< 175 mg/dL)

Pancreatitis risk> 10 mmol/L (> 880 mg/dL)

Conversionmmol/L × 88.6 = mg/dL

Figure 1. Triglyceride levels and their main clinical consequences.

Fasting or not?

After a meal, triglycerides rise for several hours. Most lipid tests can be taken without fasting, and the European guidelines accept non-fasting samples. If non-fasting triglycerides are above 5 mmol/L (440 mg/dL), repeating the test after an overnight fast should be considered.

Causes of high triglycerides

Lifestyle: excess calories, sugar and refined carbohydrates, alcohol, abdominal obesity, inactivity
Metabolic: insulin resistance, type 2 diabetes (especially poorly controlled), metabolic syndrome, fatty liver
Other conditions: hypothyroidism, chronic kidney disease and nephrotic syndrome, pregnancy
Medicines: corticosteroids, oestrogens, tamoxifen, retinoids, some antipsychotics, thiazides, beta-blockers, protease inhibitors
Genetic: familial hypertriglyceridaemia, familial combined hyperlipidaemia, rare familial chylomicronaemia syndrome

Clinical significance

Triglyceride-rich lipoproteins and their remnants contain cholesterol and apolipoprotein B and contribute to atherosclerosis. High TG usually comes with low HDL-C and small, dense LDL particles — the "atherogenic dyslipidaemia" of insulin resistance. The first step is to treat the cause: lose weight, limit sugar and alcohol, exercise and control diabetes. Medicines (statins, fibrates, omega-3 icosapent ethyl) are chosen according to overall risk.

Seek urgent care

if you have severe upper abdominal pain spreading to the back, with nausea or vomiting, especially if your triglycerides are known to be very high. This may be acute pancreatitis.

References

Mach F, Baigent C, Catapano AL, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. Eur Heart J. 2020;41(1):111–188. doi:10.1093/eurheartj/ehz455
Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol. Circulation. 2019;139(25):e1082–e1143. doi:10.1161/CIR.0000000000000625
Nordestgaard BG, Langsted A, Mora S, et al. Fasting is not routinely required for determination of a lipid profile: clinical and laboratory implications including flagging at desirable concentration cut-points — a joint consensus statement from the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine. Eur Heart J. 2016;37(25):1944–1958. doi:10.1093/eurheartj/ehw152

This article is for general information and does not replace a consultation with a doctor. Laboratory results must be interpreted by a physician together with symptoms and other tests.

Published on 30 June 2019

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