- 01Low triglycerides are read by their company
A low triglyceride number on its own sits inside the healthy range and usually reflects good insulin sensitivity, a fasted test or a lipid medicine. It becomes a clue only when LDL and total cholesterol are low too, or when symptoms of poor fat absorption appear. The rest of the lipid panel, more than the triglyceride number, decides which story you are in.
A triglyceride result of 30, 40 or 50 mg/dL looks alarming when a lab prints it next to a range of 0 to 149, yet no US or European guideline defines a lower limit for triglycerides at all 1. People born with gene variants that keep their triglycerides low for life have about 40% less coronary heart disease 3. What turns a low triglyceride reading into a clue is the company it keeps on your lipid panel: low triglycerides with normal LDL and healthy HDL is the profile doctors hope to see, while low triglycerides with very low LDL and total cholesterol points somewhere else. For what triglycerides are and how the whole marker works, start with the triglycerides overview; for readings of 150 mg/dL or more, see high triglycerides.
What counts as low triglycerides
Triglyceride categories come from the American Heart Association and the US cholesterol program: under 150 mg/dL (1.7 mmol/L) is normal, 150 to 199 mg/dL is borderline high, 200 to 499 mg/dL is high and 500 mg/dL or more is very high 1. The AHA added an optimal fasting level of under 100 mg/dL (1.1 mmol/L) 1. No guideline defines a low category, so there is no point at which triglycerides are officially too low. The 35, 40 and 50 mg/dL cutoffs that some websites quote are house conventions without a source, which is why each site picks a different one. The strip and table below show the official bands and where common low readings fall inside them.
Where an example low triglyceride reading fallsmg/dL
| Triglyceride level | US units | SI units | What it usually means | Usual next step |
|---|---|---|---|---|
| Optimal, including very low readings (no official low category) | Under 100 mg/dL | Under 1.1 mmol/L | The insulin-sensitive range the AHA calls optimal 1. Very low readings here are usually lean, fasted or active people, or lipid medicines; rarely an inherited low-lipid disorder or poor fat absorption 7 | Read LDL and total cholesterol on the same report |
| Normal | 100 to 149 mg/dL | 1.1 to 1.6 mmol/L | Normal 1 | Nothing |
| Borderline high and above | 150 mg/dL or more | 1.7 mmol/L or more | Above the normal range 1 | See the high triglycerides page |
"Very low LDL" has a meaning here too. Doctors look into an inherited low-lipid disorder when LDL or apoB (a count of the particles that carry cholesterol and triglycerides) is below the 5th percentile for age and sex 7. As a rough guide, for most adults not on a cholesterol medicine that is an LDL somewhere under about 60 to 70 mg/dL (1.6 to 1.8 mmol/L), depending on age and sex; your clinician can check where yours falls. On a statin, a low LDL is the medicine working. Your lab reports mmol/L instead? Convert with the cholesterol units calculator (divide triglycerides in mg/dL by 88.6).
Is it bad to have low triglycerides?
For most people, low triglycerides are good news. Triglycerides rise when the body is insulin resistant, because the liver turns spare sugar into fat and exports it into the blood. In overweight adults, a triglyceride to HDL ratio of 3.0 or more (in mg/dL) picked out the insulin-resistant group 8, so low triglycerides and high HDL together are the pattern of an insulin-sensitive metabolism. Insulin resistance explains the opposite pattern.
The strongest reassurance about low triglycerides comes from genetics. APOC3 makes a protein that slows the clearance of triglyceride-rich particles from the blood. The NHLBI Exome Sequencing Project reported that "rare mutations that disrupt APOC3 function were associated with lower levels of plasma triglycerides and APOC3" and that carriers "were found to have a reduced risk of coronary heart disease" 3. A rarer variant pattern, two non-working copies of ANGPTL3, lowers triglycerides, LDL and HDL all together, a condition called familial combined hypolipidemia 9.
Your cholesterol ratios, in context
Two ratios that say more than any single number. Nothing leaves your browser.
Is the low reading real?
Before looking for a cause, check whether the low triglyceride number is real and repeatable. These factors explain a single low flag far more often than any disease, listed from most to least common.
- Fasting and timing: a fasted sample reads lower. An ordinary meal raises triglycerides by only about 0.3 mmol/L (roughly 26 mg/dL) at its peak, so fasting lowers the number a little and is unlikely to explain a very low result on its own 2. See fasting before a blood test.
- Day-to-day swing: triglycerides vary within one person several times more than total cholesterol does, so two readings a few weeks apart can differ noticeably 10.
- Lab interference: N-acetylcysteine (NAC) at the blood levels reached during hospital treatment causes falsely low results with the standard method most labs use for triglycerides and cholesterol 6. See supplements that affect blood tests.
- Lab-to-lab differences: methods and calibration differ, so compare readings from the same lab. Reference ranges explained covers why.
Retest rule: if your LDL and total cholesterol are normal and you feel well, clinicians usually leave a low triglyceride result until your next routine check. If cholesterol is low too, or nothing explains the reading (no long fast, no new medicine, no recent weight loss), they usually repeat it at the same lab after a few weeks, at the same time of day and with the same fasting time. The EAS/EFLM consensus panel concluded that fasting is not routinely required for a lipid profile 2, so a non-fasting repeat works as long as it matches the first test. There is no danger level for low triglycerides; the only reasons to be seen quickly are the symptoms in the warning box below.
Why are my triglycerides suddenly so low?
A drop from 150 to 50 mg/dL looks dramatic, but triglycerides respond within weeks to changes in diet, weight, alcohol and medicines 1. Lifestyle changes alone can lower them by 20% to 50% 1. Run through what changed before the second test:
- Started or changed a fibrate, statin or prescription omega-3 1.
- Lost weight, including on a weight-loss medicine.
- Cut back on alcohol, sugar or refined carbohydrates, or went low-carb or keto 1.
- Fasted longer before the draw, or used a different lab 2.
- Were recently ill, ate little, or took high-dose NAC 6.
If one of these fits, the fall is expected. Compare the trend at the same lab rather than two single results; why trends beat single readings explains how.
Causes of low triglycerides
Common
| Cause | How it lowers triglycerides | Clue | Test that checks it |
|---|---|---|---|
| Lean, active, insulin sensitive | Muscle clears triglyceride-rich particles fast and the liver makes less fat 1 | Healthy HDL, normal LDL, low TG to HDL ratio 8 | HDL and the triglyceride to HDL ratio |
| Recent lifestyle change | Weight loss, less alcohol and sugar, and more exercise lower triglycerides by 20% to 50% 1 | New diet, keto or weight loss in the last few months | Repeat lipid panel showing a trend |
| Lipid-lowering medicines | Fibrates lower triglycerides 30% to 50%, prescription omega-3 20% to 50%, statins and niacin 10% to 30% 1 | Started or changed a prescription | Medicine list; repeat lipid panel |
| Fasted test or lab difference | Fasting and day-to-day swing lower one reading 210 | Long fast before the draw; a different lab from last time | Repeat at the same lab |
Things that push triglycerides down
Less common
| Cause | How it lowers triglycerides | Clue | Test that checks it |
|---|---|---|---|
| Overactive thyroid | Thyroid hormone speeds lipid clearance; total and LDL cholesterol fall consistently, triglycerides only a little and inconsistently 5 | Palpitations, heat intolerance, tremor, weight loss; low cholesterol more than low triglycerides | TSH and free T4; see hyperthyroidism |
| Fat malabsorption (celiac disease, pancreatic insufficiency, Crohn's) | Less dietary fat reaches the blood 7 | Greasy pale stools, diarrhea, often with bloating, weight loss, low vitamins A, D, E | tTG-IgA, fecal elastase; see celiac disease |
| Not eating enough | Less fat and sugar to build triglycerides from 7 | Weight loss, low albumin | Albumin |
| Advanced liver disease | A damaged liver makes fewer of the particles that carry fat in the blood 7 | Low albumin, raised INR (slow blood clotting), abnormal liver enzymes | Albumin, INR, ALT |
Must not miss
| Cause | How it lowers triglycerides | Clue and red flag | Test that checks it |
|---|---|---|---|
| Familial hypobetalipoproteinemia | One faulty APOB gene lowers apoB and LDL to roughly a quarter to a half of normal; affects roughly 1 in 1,000 to 1 in 3,000 people and is linked to fatty liver 7 | LDL and apoB both below the 5th percentile, often in several relatives | ApoB, LDL, then genetic testing |
| Abetalipoproteinemia | Both copies of the MTTP gene (which loads fat onto apoB) are faulty, so almost no apoB-containing particles form; fewer than 1 in 1,000,000 people 4 | Red flag: triglycerides and LDL near zero with fatty stools in childhood, poor growth, balance problems or night blindness; needs a specialist soon 4 | Vitamin E, vitamin A, apoB, a blood smear looking for spiky red cells (acanthocytes) |
Symptoms
Low triglycerides are not known to cause symptoms themselves. Claims that a low triglyceride level disturbs hormones, memory or body temperature are not backed by human studies. When symptoms appear, they come from the cause, and the ones worth acting on are listed below.
Related symptom pages: unexplained weight loss, tingling in the hands and feet, easy bruising and heart palpitations.
Read it with your other markers
Read low triglycerides beside these
| Pattern | What it suggests | Read more |
|---|---|---|
| Low TG, healthy HDL, normal LDL | Insulin-sensitive, healthy profile 18 | Lipid panel guide |
| Low TG, high LDL, on a low-carb diet | A diet pattern is common; a high LDL still needs a clinician's read, and apoB gives the truer particle count | ApoB vs LDL |
| Low TG, low LDL, low total cholesterol | Overactive thyroid, malabsorption, liver disease or hypobetalipoproteinemia 57 | Thyroid panel guide |
| Low TG with low albumin | Poor intake or liver disease 7 | Low albumin |
| Low TG with low HDL | Low HDL needs its own read; all three low together can be inherited 9 | Low HDL |
| TG and LDL near zero, low vitamin E | Abetalipoproteinemia; specialist referral 4 | See must-not-miss causes above |
For how the ratios on a lipid report are built, see blood test ratios.
What to do with your result
- Low triglycerides, normal LDL and HDL, and you feel well: nothing extra is needed; your next routine check is enough 1.
- Low triglycerides with low LDL or total cholesterol, or no clear reason: book a routine appointment and ask about a repeat lipid panel with TSH, albumin, liver tests and apoB 57.
- Any of the symptoms in the warning box: be seen within days.
- On a statin, fibrate or prescription omega-3: the low number is the medicine working, so keep taking it unless your prescriber says otherwise 1.
What usually happens next
How a doctor typically works up low triglycerides
What can bring it up
No treatment targets a low triglyceride number, and no study shows that raising it improves health. Treatment goes to the cause: thyroid treatment for an overactive thyroid, a gluten-free diet for confirmed celiac disease, enzyme replacement for pancreatic insufficiency, and specialist care with vitamin replacement for abetalipoproteinemia 45. If a fibrate, statin or prescription omega-3 drove the number down, that is the medicine working 1; do not stop or reduce a prescribed medicine because of a low triglyceride reading, and raise it with the prescriber instead. Eating more fat or sugar to push triglycerides up is not recommended by any guideline.
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Citations
- Miller M, Stone NJ, Ballantyne C, et al. Triglycerides and cardiovascular disease: a scientific statement from the American Heart Association. Circulation. 2011;123(20):2292-2333.
- 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.
- TG and HDL Working Group of the Exome Sequencing Project, National Heart, Lung, and Blood Institute. Loss-of-function mutations in APOC3, triglycerides, and coronary disease. N Engl J Med. 2014;371(1):22-31.
- Burnett JR, Hooper AJ, Hegele RA. Abetalipoproteinemia. In: GeneReviews. Seattle (WA): University of Washington, Seattle; 2018 (updated).
- Duntas LH, Brenta G. The effect of thyroid disorders on lipid levels and metabolism. Med Clin North Am. 2012;96(2):269-281.
- Genzen JR, Hunsaker JJH, Nelson LS, Faine BA, Krasowski MD. N-acetylcysteine interference of Trinder-based assays. Clin Biochem. 2016;49(1-2):100-104.
- Welty FK. Hypobetalipoproteinemia and abetalipoproteinemia. Curr Opin Lipidol. 2014;25(3):161-168.
- McLaughlin T, Abbasi F, Cheal K, Chu J, Lamendola C, Reaven G. Use of metabolic markers to identify overweight individuals who are insulin resistant. Ann Intern Med. 2003;139(10):802-809.
- Musunuru K, Pirruccello JP, Do R, et al. Exome sequencing, ANGPTL3 mutations, and familial combined hypolipidemia. N Engl J Med. 2010;363(23):2220-2227.
- Smith SJ, Cooper GR, Myers GL, Sampson EJ. Biological variability in concentrations of serum lipids: sources of variation among results from published studies and composite predicted values. Clin Chem. 1993;39(6):1012-1022.
Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.
