Low LDL cholesterol: is it a problem?
No, unless it’s very low and you’re not on cholesterol medicine. The healthy level is below 3, with no floor. But under 1.3 without that medicine is worth checking. Liver and thyroid checks come first.
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Is low LDL cholesterol bad?
Usually not. HEART UK puts healthy LDL below 3.0 mmol/L. It gives no lower limit.
Think of 3.0 as a 30 mph limit. Driving at 15 is safe. But if your car won’t go faster than 15, a mechanic would ask why.
LDL works the same way. If yours is low without a statin, the question is why.
MSD Manual, a doctors’ reference, calls LDL below 1.3 mmol/L low. If you take no cholesterol medicine, it says a result like that should lead to checks for a cause.
- Below 1.3 mmol/LMSD: low. No cholesterol medicine? Ask why.
- 1.3 to just under 3 mmol/LHealthy for adults.
- 3 mmol/L or aboveAbove healthy.
Sources: HEART UK; MSD Manual
On a statin and low? That’s often the aim.
Not on one and under 1.3? Ask your GP whether liver and thyroid tests are worth doing.
Why do doctors aim for low LDL?
Because lower LDL is linked to less heart disease. If you have heart or circulation disease, such as after a heart attack or stroke, NICE aims for LDL of 2.0 mmol/L or less.
NICE’s experts said LDL should be cut as much as possible in people with heart or circulation disease.
| Who | LDL (mmol/L) | What it means |
|---|---|---|
| Healthy adults | Below 3.0 | HEART UK healthy level. No lower limit. |
| Heart or circulation disease (such as after a heart attack or stroke) | 2.0 or less | NICE aim on cholesterol medicines. |
| Anyone not on cholesterol medicine | Below 1.3 | MSD: low. Look for a cause. |
Sources: HEART UK; NICE NG238; MSD Manual
Getting LDL that low with medicines is remarkably safe, a 2024 review found. Statins may slightly raise the risk of diabetes and of bleeding in the brain. The review says the benefits outweigh those risks.
Never stop or change a prescribed medicine without your prescriber. See blood tests on statins.
What causes low LDL without a statin?
Most often, something other than your genes. MSD says causes like these are far more common than inherited ones.
| Cause | In plain words |
|---|---|
| Overactive thyroid | Your thyroid gland makes too much hormone. |
| Malabsorption | Your gut doesn’t take in food properly. |
| Undernutrition | Not getting enough food, including with long-term heavy drinking. |
| Long-term infection or inflammation | Such as hepatitis C. |
| Cancer | Including cancers of the blood. |
| Long-term liver disease | Liver damage that lasts. |
| Strict vegan diet | No animal foods at all. |
Sources: MSD Manual; Endotext
Been ill lately, or had a baby? The NHS says your levels may be lower or higher. Some medicines can do this too.
So which checks come first? Your liver and your thyroid. MSD advises liver enzyme tests (ALT and AST) and a thyroid test (TSH).
Checks MSD advises after an unexpected low LDL
- 1
Medicines
Make sure you’re not on a cholesterol medicine.
- 2
Liver and thyroid
Blood tests for ALT, AST and TSH.
- 3
Normal results
An inherited cause is possible.
Source: MSD Manual
More on each test: liver function tests and thyroid and cholesterol.
Can low LDL run in families?
Yes. The main inherited cause is familial hypobetalipoproteinaemia (FHBL). It affects about 1 in 1,000 to 3,000 people.
The mildest cases cause no signs at all. But many people with FHBL get fatty liver, a build-up of fat in the liver. In severe cases, this can lead to lasting liver damage (cirrhosis).
Severe FHBL makes it hard to absorb fat and vitamins A and E. That can cause fatty poo.
If you inherit the gene change from one parent, the main signs are fatty liver and slightly raised liver enzymes, a 2014 review found. See fatty liver blood tests.
If low cholesterol runs in your family, tell your GP.
What to do about a low LDL result
What to do about a low LDL result
- On a cholesterol medicine? Keep taking it. Never stop or change a prescribed medicine without your prescriber.
- Not on one and under 1.3? Ask your GP whether liver and thyroid tests are worth doing.
- Ill lately or had a baby? Ask whether a repeat test later makes sense.
- Tell your GP if you’ve lost weight without trying.
- Tell your GP if you drink heavily or eat very little.
- Tell your GP if low cholesterol runs in your family.
Sources: MSD Manual; NHS
For the other end of the scale, see LDL cholesterol and LDL levels by age.
When to speak to a GP
Low LDL usually causes no symptoms. It’s often found by chance on a routine test. Book an appointment if:
- Your LDL is under 1.3 and you take no cholesterol medicine. MSD advises checks for a cause.
- You keep losing weight without changing your diet or exercise.
- You have signs of an overactive thyroid, such as nervousness, trembling, a fast or irregular heartbeat, or weight loss despite eating more.
- You have fatty poo, or have been told you have fatty liver, and your LDL is low.
See also overactive thyroid symptoms.