Hypertriglyceridaemia-induced acute pancreatitis accounts for approximately 2-4% of all cases of acute pancreatitis (after gallstones and alcohol) and is the most important life-threatening complication of very high triglycerides. The pathophysiology: hydrolysis of excess triglycerides in pancreatic capillaries by local lipases releases free fatty acids that are directly cytotoxic to pancreatic acinar cells. The clinical trap: amylase and lipase levels may be falsely low or normal in hypertriglyceridaemia-induced pancreatitis because lipaemia interferes with the enzyme assay — the diagnosis can be missed if only amylase/lipase are measured. The CT abdomen (or MRI pancreas) confirms pancreatitis regardless of lipase levels. The treatment principle: rapidly reduce triglycerides to below 5 mmol/L using: (1) nil by mouth (stops exogenous lipid supply); (2) IV insulin infusion (activates lipoprotein lipase — LPL — which breaks down circulating VLDL/chylomicrons); (3) IV dextrose to prevent hypoglycaemia during insulin infusion; (4) plasmapheresis for extremely high levels (>22 mmol/L) or clinical deterioration.

The secondary causes of hypertriglyceridaemia are extremely common and must be excluded before attributing elevated TG to a primary genetic cause — in UK primary care, the vast majority of patients with TG above 3 mmol/L have a secondary cause. The most important to identify and treat: (1) uncontrolled T2DM — insulin deficiency or resistance reduces lipoprotein lipase activity, allowing VLDL and chylomicrons to accumulate; HbA1c should be checked in every patient with TG above 3 mmol/L; (2) hypothyroidism — reduces both hepatic LDL receptor activity (raising LDL) and LPL activity (raising TG); TSH should be checked in all dyslipidaemia workups; (3) alcohol — even moderate-to-heavy drinking can raise TG significantly; enquire specifically about alcohol use in every patient with elevated TG; (4) medications — corticosteroids, thiazide diuretics, and oestrogen-containing preparations can all raise TG meaningfully. The practical rule: treat the secondary cause first; re-check TG after the secondary cause has been addressed before considering primary pharmacological treatment for TG.

The Friedewald equation for calculating LDL (LDL = total cholesterol - HDL - TG/2.2) is unreliable when triglycerides exceed 4.5 mmol/L — at very high TG concentrations, the TG/2.2 term (used to estimate VLDL) disproportionately underestimates VLDL, causing LDL to be significantly underestimated. This means that in a patient with TG of 8 mmol/L, the calculated LDL may appear reassuringly normal (or even low) while the actual LDL and atherogenic particle burden is substantially higher. The solution: use non-HDL cholesterol (total cholesterol minus HDL) as the primary cardiovascular risk marker when TG exceeds 4.5 mmol/L — it captures all atherogenic lipoproteins (LDL, VLDL, IDL, Lp(a)) without relying on the Friedewald calculation. Target non-HDL cholesterol for primary prevention is below 3.4 mmol/L; for secondary prevention below 2.5 mmol/L. Direct LDL measurement (by specific laboratory assay rather than calculation) is also available and accurate regardless of TG level — useful in high-TG patients.

The metabolic syndrome is a cluster of cardiovascular and metabolic risk factors that are physiologically linked through insulin resistance — it affects approximately 25-30% of UK adults and is strongly driven by central obesity. The mechanism: central adiposity (visceral fat) releases excess free fatty acids into the portal circulation, driving hepatic triglyceride synthesis (VLDL overproduction). Insulin resistance impairs lipoprotein lipase activity (the enzyme responsible for clearing TG from blood), causing TG to accumulate. The resulting lipoprotein profile (high TG + low HDL + small dense LDL) is the 'atherogenic dyslipidaemia' of metabolic syndrome. The good news: this pattern is highly responsive to lifestyle modification. Weight loss of 5-10% body weight typically reduces TG by 20-30%, raises HDL by 5-10%, and often resolves the metabolic syndrome criteria entirely. This is why lifestyle intervention is the cornerstone of treatment for hypertriglyceridaemia in primary care — pharmacological therapy is an adjunct, not a substitute.

The familial chylomicronaemia syndrome (FCS) referral is urgent and important — FCS is caused by biallelic loss-of-function mutations in LPL or its cofactors (apoC-II, apoA-V, LMF1, GPIHBP1), causing near-complete absence of functional lipoprotein lipase. TG levels are typically above 20 mmol/L (and can exceed 100 mmol/L). The condition is rare (1 in 1 million) but causes recurrent life-threatening pancreatitis from childhood. Standard lipid-lowering drugs (statins, fibrates, niacin, omega-3) are largely ineffective because the LPL enzyme itself is absent. The transformative new treatment is volanesorsen (Waylivra — ionis/Akcea) — an antisense oligonucleotide targeting apoC-III mRNA in the liver, reducing apoC-III production (apoC-III normally inhibits LPL activity; in FCS where LPL is absent, reducing apoC-III reduces TG via LPL-independent pathways). Volanesorsen reduces TG by approximately 80% in FCS patients. It was approved by EMA in 2019 and should be initiated at a specialist centre after FCS confirmation by genetic testing.

The dietary sugar-TG connection is one of the most practically important and under-communicated nutritional facts in primary care — many patients who reduce dietary fat (as traditionally advised for dyslipidaemia) inadvertently increase their carbohydrate intake, particularly from refined sugars and fruit juices, which actually worsens hypertriglyceridaemia. The biochemical mechanism: fructose (the sugar in table sugar, high-fructose corn syrup, and fruit juice) is metabolised almost exclusively in the liver, where it bypasses the rate-limiting enzyme of glycolysis (phosphofructokinase) and is shunted directly into lipogenesis via de novo lipogenesis (DNL) — converting fructose to fatty acids that are packaged as VLDL-TG for export into the bloodstream. A single 500ml bottle of fruit juice contains approximately 30g of fructose — equivalent to the liver lipogenic stimulus of approximately 3-4 units of alcohol. The practical message for patients: 'For high triglycerides, the single most important dietary change is cutting out sugary drinks, fruit juices, and refined carbohydrates — this is more important than cutting fat.'

The REDUCE-IT trial (2018) is one of the most important cardiovascular pharmacology trials of the last decade — it showed that high-dose icosapentaenoic acid (EPA, 4 g/day as Vascepa/Vazkepa) reduced major adverse cardiovascular events (MACE — MI, stroke, cardiovascular death) by 25% (relative risk reduction) in patients with established cardiovascular disease or diabetes who had elevated TG (above 1.5 mmol/L) despite statin therapy. The absolute risk reduction was approximately 4.8% over 4.9 years (NNT approximately 21 for 5 years). The mechanisms proposed: TG lowering; anti-inflammatory effects of EPA; anti-oxidant effects; membrane stabilisation effects on vulnerable plaques. The result was controversial because the control arm used mineral oil (which may have raised cardiovascular risk) rather than olive oil or corn oil, potentially inflating the treatment effect. Despite the controversy, NICE has approved EPA (Vazkepa) for secondary cardiovascular prevention in patients with TG above 1.7 mmol/L on statin therapy (NICE TA805, 2022). GPs managing patients with established CVD and TG above 1.7 mmol/L on statin should consider EPA as an add-on treatment.

The postprandial TG response is an underappreciated cardiovascular risk factor — fasting TG measurement captures only a fraction of the TG burden in most people, as TG levels are highest postprandially (2-4 hours after a fat-containing meal). Studies consistently show that postprandial hypertriglyceridaemia is a cardiovascular risk factor independent of fasting TG, because the postprandial state (lasting approximately 16-18 hours in adults eating three meals per day) is when TG-rich lipoproteins are present in the circulation and driving atherosclerosis. The practical implication: a patient whose fasting TG is 3 mmol/L will have postprandial TG of 6-8 mmol/L — the actual TG exposure over 24 hours is dramatically higher than the fasting measurement suggests. Non-fasting lipid measurement (Total cholesterol + HDL + non-HDL cholesterol) is now recommended as the preferred screening approach in many guidelines precisely because it captures part of the postprandial TG burden.

The TG response to treatment is one of the most dramatic and rapid in lipidology — in contrast to LDL which takes weeks to respond to statins, triglycerides can fall by 30-60% within days of: stopping alcohol, eliminating sugary drinks, commencing fenofibrate, or starting a very-low-calorie diet. This rapid response has clinical utility: it allows early reassessment (3-4 weeks rather than 3 months) to confirm treatment response and reinforce lifestyle change. Sharing the TG result with the patient at each review — and pointing out the improvement — is one of the most motivating tools in metabolic medicine. A patient who sees their TG fall from 8.5 to 3.2 mmol/L within 6 weeks of stopping alcohol and soft drinks has powerful objective evidence of the impact of their lifestyle change.