What the triglycerides test shows
Triglycerides are the body’s main storage form of fat — the calories you don’t burn, carried in the blood inside fat-rich particles (chylomicrons after eating, VLDL between meals). The test measures this circulating fat, one of the four core numbers on a lipid panel. MedlinePlus calls it a blood fat that, when high, raises the risk of heart disease and stroke.
It differs from the cholesterol beside it: cholesterol builds membranes, hormones and bile, while triglycerides are energy. LDL cholesterol and HDL cholesterol carry cholesterol; triglycerides ride mainly in VLDL, so the two can diverge — high triglycerides with a low HDL is a common pattern. Labs also calculate LDL from total cholesterol, HDL and triglycerides (the Friedewald equation), which fails above about 400 mg/dL — then the report turns to a measured LDL, non-HDL cholesterol or apoB instead.
Triglycerides normal range
Triglycerides are reported in mg/dL (US) and mmol/L (SI); the two are not interchangeable — divide mg/dL by about 88.5. The cut-points are the same for adult men and women, read against fixed categories, per the AHA:
| Category (fasting, adult) | Conventional, mg/dL | SI, mmol/L |
|---|---|---|
| Optimal | < 100 | < 1.1 |
| Desirable (normal) | < 150 | < 1.7 |
| Borderline-high | 150–199 | 1.7–2.2 |
| High | 200–499 | 2.3–5.6 |
| Very high | ≥ 500 | ≥ 5.6 |
Levels still drift — higher in men through midlife, rising in women after menopause — and children have lower cut-points. Timing matters more here than for any other lipid: eating lifts triglycerides for hours, so while current guidance accepts a non-fasting sample for screening, a high value is rechecked fasting (9–12 hours) first. Ranges depend on the lab, sex and age — read against your own report.
Why triglycerides are high
High triglycerides (hypertriglyceridemia) are common, usually driven by metabolism and lifestyle. Roughly by frequency:
- Insulin resistance and its cluster: type 2 diabetes, prediabetes, metabolic syndrome, central weight gain and fatty liver. High triglycerides with a low HDL is the classic signature, so glucose and HbA1c are checked alongside.
- Diet and alcohol: refined carbohydrate, sugar and sugary drinks raise triglycerides fast; alcohol is a potent trigger.
- A recent meal — a common cause of a mildly raised, non-fasting result, not a disease in itself.
- Medications: oral estrogen, corticosteroids, thiazide diuretics, beta-blockers, retinoids and some immunosuppressants.
- Other conditions: an underactive thyroid, chronic kidney disease, nephrotic syndrome and pregnancy — so a TSH is a routine cross-check.
- Genetic disorders: familial combined hyperlipidemia and familial hypertriglyceridemia; rare chylomicronemia pushes levels into the thousands from childhood.
Above 500 mg/dL, and especially 1000 mg/dL (11.3 mmol/L), the danger shifts from the arteries to the pancreas: very high triglycerides can trigger acute pancreatitis, StatPearls notes — severe abdominal pain with a known very-high level needs same-day care.
Why triglycerides are low
A low triglyceride is far less often a concern than a high one and is usually reassuring, but can occasionally flag a problem. Roughly by frequency:
- A lean diet and healthy habits: fasting, a low-fat or low-carbohydrate diet, weight loss and endurance exercise all lower triglycerides — the harmless kind of low.
- Lipid-lowering treatment: statins, fibrates, high-dose omega-3 and niacin bring the number down by design.
- An overactive thyroid (hyperthyroidism), which speeds fat clearance; a suppressed TSH points this way.
- Malnutrition or malabsorption, including celiac disease, or chronic illness with low food intake.
- Rare inherited conditions — hypobetalipoproteinemia and abetalipoproteinemia — cause very low triglycerides and LDL, and in children can lead to vitamin deficiency and neurological problems.
An unexpectedly low level — with weight loss, digestive symptoms or a family history — is worth raising with your doctor; a modestly low value in a well person rarely needs action.
What to test alongside
Read with the rest of the lipid panel and a few metabolic cross-checks (our guide to the modern lipid panel shows how they fit together):
- Total cholesterol, LDL cholesterol and HDL cholesterol — the rest of the panel; HDL is often low when triglycerides are high.
- Cholesterol ratio — total-to-HDL, a quick risk summary.
- ApoB — the atherogenic particle count, useful when LDL is unreliable.
- ApoA1 — the main protein of protective HDL.
- Lipoprotein(a) — an inherited, independent risk factor.
- Glucose and HbA1c — the insulin resistance usually behind high triglycerides.
- TSH — thyroid shifts triglycerides either way; ALT — fatty liver travels with them; CRP — inflammatory risk context.
What to do about an abnormal result
- Don’t panic over one number, and don’t self-treat. A single raised value — especially non-fasting — is often just diet, alcohol or meal timing.
- Repeat fasting if needed. A high screening result is usually rechecked after a 9–12 hour fast.
- For borderline or high triglycerides, start with lifestyle: cut added sugar, refined carbohydrate and alcohol, lose excess weight and add activity — this alone can lower them substantially within weeks. Current ACC/AHA dyslipidemia guidance treats a high triglyceride mainly as a signal to control the underlying metabolic risk.
- For very high triglycerides (≥ 500 mg/dL), the priority is preventing pancreatitis; your doctor addresses contributors (diabetes, alcohol, medications) and may add a drug such as a fibrate.
- See your GP or primary-care doctor first. They coordinate the work-up and refer stubborn or clearly genetic cases to a lipid specialist.
Mini-FAQ
Do I need to fast before a triglyceride test?
Not always. Non-fasting samples are accepted for routine screening, but because eating raises triglycerides for hours, a fasting sample (9–12 hours) is used when a level is high or to track known high triglycerides.
What triglyceride level is considered high?
Fasting, under 150 mg/dL (1.7 mmol/L) is normal, 150–199 borderline-high, 200–499 high, and 500 mg/dL (5.6 mmol/L) or more very high. Above 500, and especially 1000, the main danger becomes pancreatitis rather than heart disease.
Are high triglycerides as dangerous as high LDL cholesterol?
They flag risk differently. LDL cholesterol drives artery plaque directly, while triglycerides mainly mark insulin resistance and remnant particles and cause pancreatitis only when very high. Doctors often add non-HDL cholesterol or apoB for the full picture.
Can I lower triglycerides without medication?
Often yes. Cutting added sugar, refined carbohydrate and alcohol, losing excess weight and exercising can lower triglycerides substantially within weeks. Medication is added mainly for very high levels or persistent cardiovascular risk.
Should I worry about a low triglyceride result?
Usually not — a low level is generally reassuring and often reflects fasting, weight loss or a healthy diet. Very low readings occasionally point to an overactive thyroid, malabsorption or a rare inherited condition.
