01OverviewDefinition, clinical context and the essential points that orientate the chapter.
Triglycerides circulate in chylomicrons after meals and in liver-derived VLDL. Severe accumulation, especially of chylomicrons, makes serum visibly lipaemic and can trigger pancreatic inflammation. Concentrations fluctuate with food, alcohol and glycaemia, which is why NICE specifies a prompt fasting repeat in the 10-to-20 mmol/L range while secondary factors are addressed.
Most adult presentations are multifactorial: polygenic susceptibility plus uncontrolled diabetes, alcohol, central adiposity, pregnancy or a triglyceride-raising medicine. Familial chylomicronaemia syndrome is rare, often begins young, responds poorly to ordinary triglyceride medicines and causes recurrent pancreatitis; multifactorial chylomicronaemia is far more common. Eruptive xanthomata and recurrent unexplained pancreatitis are useful clues, not a genetic diagnosis.
Management separates pancreatitis prevention from atherosclerotic prevention. Very-low-fat nutrition, removal of alcohol, glycaemic control and specialist triglyceride-lowering therapy address chylomicrons. Once triglycerides permit reliable calculation, non-HDL, LDL and overall cardiovascular risk determine statin and adjunct use. Icosapent ethyl has a specific cardiovascular appraisal and should not be misrepresented as emergency treatment for chylomicronaemia.
Key points
- Triglycerides between 10 and 20 mmol/L require a fasting repeat after at least five days but within two weeks, plus immediate review of secondary causes.
- Seek specialist advice if the repeat fasting concentration remains above 10 mmol/L; refer urgently above 20 mmol/L when alcohol or poor glycaemic control does not explain it.
- Acute pancreatitis risk rises substantially with severe triglyceride elevation, but pain and organ dysfunction determine emergency care rather than a lipid number alone.
- Uncontrolled diabetes or DKA, alcohol, pregnancy, obesity, hypothyroidism, renal disease and medicines are common reversible or aggravating factors.
- Eruptive xanthomata, lipaemic plasma, hepatosplenomegaly or lipaemia retinalis can indicate chylomicronaemia and should prompt specialist genetic consideration.
- Immediately stop alcohol and obtain dietetic advice on a temporary very-low-fat, nutritionally complete plan when chylomicrons create pancreatitis risk.
- Control marked hyperglycaemia promptly; intravenous insulin belongs to DKA, hyperglycaemic crisis or specialist acute-pancreatitis protocols, not an automatic response to every high triglyceride result.
- Fenofibrate is often used under lipid-specialist advice after renal, hepatic, gallbladder, interaction and pregnancy review; gemfibrozil is hazardous with statins.
- Statins reduce cardiovascular risk but do not lower severe chylomicron-rich triglycerides rapidly enough to be the sole pancreatitis-prevention strategy.
- Plasma exchange and other intensive therapies are not routine; critical care, lipid and pancreatitis specialists select them for exceptional severe or refractory cases.
- Once the acute risk falls, prevent recurrence by sustaining glycaemic control, alcohol abstinence where causal, dietetic follow-up, weight care and a family or genetic plan when indicated.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Multifactorial chylomicronaemia
Polygenic susceptibility combines with uncontrolled diabetes, alcohol, central adiposity, pregnancy or triglyceride-raising medicines to produce severe accumulation.
Familial chylomicronaemia
Rare inherited failure of chylomicron clearance often begins young, responds poorly to ordinary lipid medicines and causes recurrent pancreatitis.
Secondary metabolic drivers
Poor glycaemic control, hypothyroidism, kidney or liver disease and selected medicines can cause or amplify severe triglyceride elevation.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Triglyceride-rich particles accumulate
Excess production or impaired clearance raises chylomicrons and liver-derived VLDL, sometimes making serum visibly lipaemic as the process continues.
- 2Pancreatic capillaries are exposed
Large triglyceride-rich particles impair pancreatic microvascular flow and provide substrate for local free-fatty-acid release, promoting acinar-cell injury and inflammation.
- 3Pancreatic inflammation develops
Toxic free fatty acids and local ischaemia injure acinar tissue, triggering acute pancreatitis when the burden becomes severe.
- 4Atherogenic risk remains separate
Once extreme triglycerides fall, non-HDL cholesterol and the wider cardiovascular context determine residual atherosclerotic risk as the process continues.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
Persistent severe epigastric pain radiating to the back with vomiting, ileus, tachycardia or hypotension requires emergency assessment; the triglyceride may fall after fasting, so obtain an early sample.
Crops of small yellow-red papules on extensor surfaces, buttocks or trunk can appear with marked chylomicronaemia and improve when triglycerides fall.
Creamy retinal vessels at extreme concentrations are a specialist clue to chylomicronaemia; vision may be relatively preserved, so fundal appearance should trigger systemic risk assessment.
Polyuria, thirst, weight loss, ketones, acidosis or very high glucose identifies insulin deficiency as a major cause; DKA requires immediate validated emergency treatment.
Onset in childhood or youth, recurrent pancreatitis, persistent extreme fasting triglycerides and poor response to standard therapy raises monogenic lipolysis-pathway disease and specialist testing.
Oestrogens, corticosteroids, retinoids, some antipsychotics, protease inhibitors and pregnancy can expose underlying susceptibility; abrupt stopping still requires indication and maternal safety review.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Prompt fasting triglyceride profileFirst step - Why
- Confirm severe elevation after a high non-fasting result and quantify immediate risk.
- Interpretation and limitations
- For 10 to 20 mmol/L, NICE specifies repeat after five days but within two weeks; persistent above 10 needs specialist advice and above 20 may need urgent referral.
- 02
Lipase and acute pancreatitis assessment - Why
- Diagnose pancreatic inflammation when compatible abdominal symptoms occur.
- Interpretation and limitations
- Use pain, enzymes and imaging according to NICE pancreatitis guidance; gross lipaemia can interfere with assays, so communicate suspicion to the laboratory.
- 03
Glucose, HbA1c, ketones and blood gas - Why
- Find uncontrolled diabetes or DKA as a rapidly reversible driver.
- Interpretation and limitations
- Ketonaemia with acidosis is an independent emergency requiring insulin and fluids through the DKA pathway; improving insulin action can lower triglycerides quickly.
- 04
Liver, renal, TSH and urine protein tests - Why
- Identify alcohol-related, hepatic, renal, nephrotic or hypothyroid secondary causes.
- Interpretation and limitations
- Treat a credible secondary condition, then repeat the lipid pattern; more than one driver often coexists and a residual inherited tendency can remain.
- 05
Medication, alcohol and pregnancy assessment - Why
- Detect exposures that alter immediate management and medicine safety.
- Interpretation and limitations
- Quantify alcohol nonjudgmentally, reconcile prescribed and non-prescribed hormones or retinoids, and involve obstetric-lipid specialists urgently in pregnancy.
- 06
Non-HDL cholesterol and direct or later LDL - Why
- Assess atherosclerotic burden when ordinary LDL calculation is invalid.
- Interpretation and limitations
- Friedewald-calculated LDL is unreliable at high triglycerides; use non-HDL initially and reassess LDL after triglycerides fall or use laboratory specialist methods.
- 07
Specialist genetic and apolipoprotein assessment - Why
- Distinguish familial chylomicronaemia from common multifactorial disease.
- Interpretation and limitations
- Age of onset, recurrent pancreatitis, treatment response and approved gene panels guide diagnosis; do not label FCS solely from one lipaemic sample.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Non-fasting elevation
A recent meal can raise triglycerides transiently; a planned fasting repeat clarifies persistent severe disease when the person is clinically stable.
Uncontrolled diabetes
Marked hyperglycaemia and insulin deficiency increase hepatic triglyceride output and impair clearance, often improving substantially with metabolic control.
Familial chylomicronaemia
Childhood onset, recurrent pancreatitis, eruptive xanthomata and poor response to ordinary therapy favour a rare monogenic clearance defect.
Laboratory interference
Severe lipaemia can distort several assays, so discordant sodium or other biochemistry should be discussed with the laboratory.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01High resultConfirm and triage promptlyFirst stepA non-fasting triglyceride concentration is between 10 and 20 mmol/L.+
- 1Ask immediately about abdominal pain, vomiting, alcohol, diabetes symptoms, pregnancy and triglyceride-raising medicines, sending symptomatic patients to acute assessment.
- 2Arrange a fasting repeat after at least five days and within two weeks while beginning correction of obvious secondary drivers and giving alcohol and dietary safety advice.
- 3EscalationSeek lipid-specialist input if fasting triglycerides remain above 10 mmol/L, and escalate urgency if values rise, symptoms develop or pregnancy complicates care.
02PancreatitisTreat the acute abdomen and lipid triggerAbdominal pain and investigations support hypertriglyceridaemic acute pancreatitis.+
- 1Admit through the pancreatitis pathway for analgesia, goal-directed fluid, organ-support assessment and early appropriate nutrition, involving gastroenterology and critical care by severity.
- 2Stop alcohol and oral fat intake according to the acute plan, treat DKA or severe hyperglycaemia with validated insulin protocols and seek lipid specialist advice urgently.
- 3Reserve insulin outside hyperglycaemia, plasma exchange or other rapid-lowering interventions for multidisciplinary selected cases because routine outcome benefit is uncertain.
03Outpatient loweringRemove chylomicron driversSevere fasting triglycerides persist without acute pancreatitis.+
- 1Arrange urgent dietetic support for a nutritionally adequate very-low-fat approach, stop alcohol and reduce refined carbohydrate while avoiding unsafe unsupervised fasting.
- 2Optimise diabetes, thyroid and renal disease and change causal medicines only with the responsible prescriber, balancing contraceptive, psychiatric or inflammatory indications.
- 3Begin fenofibrate or another specialist-selected therapy after interaction and organ review, then repeat fasting triglycerides promptly until pancreatitis risk falls.
04Recurrence preventionSeparate pancreatic and vascular goalsTriglycerides have fallen below the immediate high-risk range.+
- 1Define whether disease is familial or multifactorial, sustain dietetic and alcohol support, and give a written plan for pain or recurrent metabolic deterioration.
- 2Recalculate non-HDL and LDL-related cardiovascular risk when analytically valid, using statin and indicated adjuncts independently of the pancreatitis-prevention medicine.
- 3Offer family assessment and specialist genetic care for early-onset persistent chylomicronaemia, including disease-specific commissioned treatment when current criteria are met.
Key medicines and prescribing safety4 treatments · regimens, roles and cautions+
Fenofibrate for severe hypertriglyceridaemia
A common adult oral regimen is 160 mg once daily for the relevant tablet formulation; exact dose varies by product and renal function, so verify the current BNF and specialist plan.Avoid severe renal or hepatic disease, gallbladder disease and pregnancy unless specialist-directed. Review creatinine, liver and muscle symptoms; statin combination increases myopathy risk, and formulations are not milligram-equivalent.
Insulin for DKA or severe hyperglycaemia
Use the current fixed-rate intravenous insulin and fluid protocol for DKA, or the specialist inpatient glycaemic regimen for another hyperglycaemic emergency, with hourly glucose and electrolyte monitoring.Do not run insulin solely to normalise triglycerides without specialist indication. Prevent hypoglycaemia and hypokalaemia, add glucose when protocol requires and never omit essential basal insulin in type 1 diabetes.
Statin for associated cardiovascular risk
Use NICE indication-specific atorvastatin 20 mg for eligible primary prevention or 80 mg for secondary prevention, adjusted for interactions and tolerability once acute metabolic instability is addressed.A statin is not adequate sole treatment for extreme chylomicronaemia. Avoid pregnancy, review liver and muscle risk, and take particular care when combined with a fibrate; do not combine gemfibrozil casually.
Disease-specific therapy for familial chylomicronaemia
Use only the current NICE-commissioned specialist regimen, such as an eligible apoC-III-targeted treatment, after genetic confirmation and multidisciplinary assessment in an experienced lipid centre.Eligibility, monitoring and available products can change. Follow product-specific platelet, hepatic, renal, injection and reproductive safeguards; it does not replace lifelong very-low-fat dietetic support.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Acute pancreatitis
Chylomicron accumulation can trigger severe pancreatic inflammation with abdominal pain, systemic inflammatory response and organ failure.
Recurrent pancreatic injury
Persistent or relapsing severe triglycerides cause repeated pancreatitis, leading to chronic pain and exocrine or endocrine pancreatic dysfunction.
Atherosclerotic cardiovascular disease
Atherogenic remnant and apoB-containing particles can coexist with chylomicrons, adding coronary, cerebral and peripheral vascular risk.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Repeat fasting triglycerides promptly after secondary-cause and treatment changes until the concentration is safely and consistently below the pancreatitis-risk range.
- Monitor glucose and ketones intensively during diabetic decompensation, then use HbA1c and home glucose data to prevent recurrence without hypoglycaemia.
- During fibrate therapy, follow renal function, liver tests and muscle symptoms according to BNF and local policy, especially if a statin is also used.
- Review dietary fat, refined carbohydrate, alcohol, weight trajectory and nutritional adequacy with a lipid-experienced dietitian rather than issuing an unsupported prohibition list.
- Ask about recurrent abdominal pain and supply a clear emergency plan; a previously high triglyceride result may be lower after several days of pancreatitis-related fasting.
- Once stable, monitor non-HDL and LDL for cardiovascular prevention separately from the fasting triglyceride goal and document both indications.
- In pregnancy or inherited chylomicronaemia, use the specialist frequency for maternal, fetal, pancreatic and nutritional review because risk can change rapidly.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Fasting can hide the peak
Triglycerides may fall quickly after pancreatitis stops oral intake, so an early pre-treatment lipid sample can preserve the causal clue.
Lipaemia can distort assays
Grossly turbid serum interferes with some sodium, amylase and other methods; warn the laboratory and interpret implausible results with analytical support.
Diabetes can be the switch
Loss of effective insulin sharply reduces lipoprotein-lipase activity and increases hepatic triglyceride output, turning moderate inherited risk into extreme chylomicronaemia.
Two lipid goals coexist
Preventing pancreatitis requires lowering triglyceride-rich chylomicrons, while preventing infarction focuses on apoB and LDL-related risk; one medicine rarely completes both jobs.
FCS is not common severe TG
Most adults have multifactorial disease and respond to treating secondary causes; very early onset, recurrent pancreatitis and poor conventional response justify monogenic investigation.
11Common pitfallsFrequent interpretation and management errors.
- 01
Ignoring abdominal pain because the triglyceride result is still pending.
- 02
Waiting months to repeat a result between 10 and 20 mmol/L.
- 03
Calling one alcohol-related non-fasting sample familial chylomicronaemia.
- 04
Using statin monotherapy as sufficient protection against triglyceride pancreatitis.
- 05
Starting insulin infusion solely for a number without diabetes or specialist indication.
- 06
Combining gemfibrozil and statin without recognising major myopathy risk.
- 07
Prescribing an extreme fat restriction without dietetic nutritional safeguards.
- 08
Forgetting pregnancy and oestrogen exposure as major modifiers of severe triglycerides.