Hypothyroidism and Cholesterol
What is cholesterol?
Cholesterol is a waxy substance that is present in every cell in our bodies. It is made in the liver or you can get it by eating animal products. Cholesterol is very important for hormone and nerve cell production and making bile acid (used to digest food).1
There are 2 main types of cholesterol – often referred to as good and bad cholesterol.
High-density lipoprotein (HDL) is often referred to as ‘good’ cholesterol. This is because it helps to get rid of unwanted cholesterol in the blood stream.
Then there’s low-density lipoprotein (LDL), which is known for being ‘bad’ cholesterol because it causes blockages within the vascular system, resulting in circulatory issues.
A good way to remember the difference between the 2 types is LDL ‘litters’ the veins and arteries whereas HDL ‘happily’ clears the litter away, improving the circulation of the blood.
What causes high cholesterol?
High cholesterol (hypercholesterolemia) is often caused by poor diet. Eating too many foods that are rich in LDL (the bad cholesterol) leads to a build-up of this fatty substance in the blood, which can cause blockages in the veins and arteries and significantly increase your risk of heart disease, heart attack and stroke.
Fatty foods, high in LDL, not only lead to high cholesterol but to weight issues and other health concerns.
Smoking and drinking too much can also lead to high cholesterol. It can also be a hereditary problem, running through families.2
Thyroid disorders can also be a cause of high cholesterol.1 Your body needs thyroid hormones not only to make good cholesterol but to get rid of the bad cholesterol. The connection between the thyroid and cholesterol is explained in more detail below.
What are the symptoms of high cholesterol?
High cholesterol doesn’t display any symptoms.2 Whilst often associated with obesity, you can be overweight without having high cholesterol. On the flip side, you can also be your ideal weight or underweight and have high cholesterol.
What is the connection between hypothyroidism and cholesterol?
If you have a thyroid disorder, and therefore your thyroid gland is producing too many or too few thyroid hormones, this imbalance can lead to abnormal cholesterol levels in the blood.1
One of the essential roles of the thyroid gland is to produce hormones that support the liver process and remove excess ‘bad’ cholesterol from the body.
Therefore, if you have an underactive thyroid (hypothyroidism) your thyroid isn’t producing enough hormones, particularly the T3 hormone (which stimulates the breakdown of cholesterol (lipolysis) and increases the number of LDL receptors) and so your body can’t break down and remove LDL cholesterol properly. This can lead to a build up of LDL in the circulatory system.3
Research tells us that 13% of nearly 9000 people tested with high cholesterol also had thyroid disorders.4
It is often the case that an overactive thyroid (hyperthyroidism) can result in lower cholesterol levels. This doesn’t have associated health concerns and there isn’t any specific medical evidence to support this as yet.1
The only way to determine if you have high cholesterol is to have blood test.2 This can be arranged by your GP or specialist.
Using the same blood sample, technicians can identify thyroid and cholesterol issues. It is likely that you will be required to fast for 8 – 12 hours before you test.1
If you have high cholesterol with a normal TSH and FT4, it would be a good idea to ask your doctor to check your FT3 levels in case you are not converting to T3 very well which, in turn, could cause high cholesterol.
Be aware that even slightly low thyroid hormone levels and/or slightly elevated TSH levels alone can cause cholesterol levels to be raised. 5
If you are unable to get FT3 testing done on the NHS, you can access it privately here
The usual treatment for high cholesterol is statins although there are non-statin options.6 Understanding the cause of high cholesterol is vital prior to determining the best course of treatment. If high cholesterol is caused by poor diet and lifestyle, then an adjustment to diet and exercise would, of course, be recommended. Cholesterol-lowering medications may also be prescribed.
If, however, the cause is connected to an underactive thyroid, then medication to treat hypothyroidism may, in turn, reduce cholesterol levels without the need for cholesterol-lowering drugs.1 Statins often cause muscular aches and pains, just like low thyroid so it could get confusing.
One study has, however, shown levothyroxine, a drug commonly used to treat hypothyroidism, not to be effective when it comes to lowering cholesterol levels. The study showed that 17 out of 23 patients who were prescribed levothyroxine did not see a reduction in LDL levels.7
This may be due to the fact that the patients did not have their FT3 taken. Liothyronine (T3) treatment may have given a different picture.
Statins may also cause an increased risk of diabetes in certain people and as normal thyroid function is essential for regulating energy metabolism and blood glucose control, statins could potentially increase the risk of diabetes in a low thyroid patient.
Statins also interfere with the production of mevalonic acid, which is a precursor in the synthesis of coenzyme Q10 (COQ10) which is an essential enzyme in the body for energy production and heart muscle health so taking some CoQ10 may be needed.8
Don’t let higher cholesterol scare you into taking statins without getting your doctor to check all your thyroid levels.
High cholesterol levels increase the risk of heart disease and stroke and must therefore be treated and monitored. Whilst an improvement in diet and lifestyle may help to reduce cholesterol levels, medication may also be required. Each case is unique and your doctor or specialist will provide information and guidance regarding the best treatment plan for you to reduce risks to your health.
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Cholesterol – a fatty substance in our blood, which is produced naturally in the liver
Hyperthyroidism – a term used to describe an over-active thyroid gland
Hypothyroidism – a term used to describe an under-active thyroid gland
Levothyroxine – a synthetic thyroid hormone commonly given to treat an underactive thyroid. It is also known as L-thyroxine
Metabolism – the chemical processes within the human body
Receptors – a specialised cell or group of nerve endings that responds to things such as hormones
- How are Thyroid and Cholesterol Related?
Medical News Today: 30 July 2018
- Triiodothyronine rapidly lowers plasma lipoprotein (a) in hypothyroid subjects.
Dullaart RP, van Doormaal JJ, Hoogenberg K, Sluiter WJ.
Neth J Med. 1995 Apr;46(4):179-84.
- Thyroid Function Testing in Patients With Newly Diagnosed Hyperlipidemia
D L Willard MD, A M Leung MD MSc, E N Pearce MD MSc
JAMA Intern Med. 2014 Feb 1; 174(2) 287-289
- Thyroid-stimulating hormone levels within the reference range are associated with serum lipid profiles independent of thyroid hormones.
Wang F1, Tan Y, Wang C, Zhang X, Zhao Y, Song X, Zhang B, Guan Q, Xu J, Zhang J, Zhang D, Lin H, Yu C, Zhao J.
J Clin Endocrinol Metab. 2012 Aug;97(8):2724-31
- Systemic Thyroid Hormone Status During Levothyroxine Therapy in Hypothyroidism: A Systematic Review and Meta-Analysis
McAninch E A, Rajan K B, Miller C H, Bianco A C
The Journal of Clinical Endocrinology & Metabolism, Volume 103, Issue 12, December 2018, Pages 4533–4542
- Coenzyme Q10 and Statin-Induced Mitochondrial Dysfunction
Richard Deichmann MD, Carl Lavie MD, Samuel Andrews MD
Ochsner J. 2010 Spring; 10(1): 16–21.
Date updated: 11/03/20 (V1.2)
Review date: 09/03/22