Other causes of high cholesterol
People are often surprised to find out they have high cholesterol or triglycerides in their blood, and our Cholesterol Helpline is often asked what could be the cause.
High levels of blood fats – which include cholesterol and triglycerides – can have many causes, including your genes, age and ethnic background and these can all add up. Here you can take a look at some of the lesser-known causes, doctors might call these 'secondary causes' of high cholesterol.
Diet and lifestyle
Lifelong habits, such as what you eat and how active you are, can affect your blood fats. So, sometimes lifestyle can be the cause.
- A diet high in saturated fat and processed foods
- Being physically inactive
- Being overweight or obese
- Having a large waist circumference:
- Too much alcohol
Some medicines can affect the amount of cholesterol and triglycerides in your blood. To see whether any medicines you're taking could have an effect, have a look at the product information leaflet which comes with them.
Some medicines raise blood fats only a little, while others raise them significantly. Don't worry or stop your medication – your doctor will be aware of the effect your medicine has and will have taken this into account when they prescribed it for you. If you are worried, talk to your GP or speak to our Cholesterol Helpline.
These common medicines are known to raise cholesterol and triglyceride levels:
- anti-retroviral drugs
- oral oestrogen
- beta blockers
If you have been prescribed any of these medicines your doctor will regularly review how you're getting on. They will adjust your treatment if needed to keep your cholesterol and or triglycerides levels in check.
If a cholesterol test shows you have high blood fats, your doctor will want to find out what's causing them. They will check for medical conditions that are known to push them up. If one of these conditions turns out to be the reason for your high blood fats, it is important to treat it and get in under control, and your doctor will talk to you about the best treatments for you.
Here are the most common conditions that push up your blood fats:
Type 2 diabetes
Undiagnosed or poorly controlled type 2 diabetes can upset the levels of triglycerides and cholesterol in your blood.
It is quite well known that type 2 diabetes causes high blood sugar. This poor control of blood sugar is caused by a lack of the hormone insulin, or it's not working properly. Normally, insulin helps take sugar out of the blood and into our cells where it can be used to make energy to move about, concentrate and digest our food.
- High triglycerides
- Too little HDL cholesterol
- Too much LDL cholesterol or the LDL cholesterol is more “sticky”
Untreated underactive thyroid gland (hypothyroidism)
The thyroid gland is a gland in the neck. It produces a hormone called thyroxine which is needed to keep our bodies running. A lack of this hormone causes the body to “run” too slowly. A lack of thyroxine is called underactive thyroid, hypothyroidism, myxoedema or Hashimoto's disease. It's quite common, especially in women between the ages of 40 and 50 years.
The fall in thyroxine can happen very slowly, so many people don't notice any signs of it. But there are symptoms that some people might notice over time:
- lacking energy
- weight gain
- slow movements, thought and speech
- pins and needles
- hair loss especially outer third of eyebrows
- dry skin.
Underactive thyroid can raise both cholesterol and triglyceride levels, but the main effect is on cholesterol. Luckily, it's easy to diagnose and treat, and once treated, your cholesterol and triglyceride levels should return to their usual levels with a few months.
You might be surprised to know that the amount of fat in your blood rises when you are pregnant. But this just reflects the fact that your body needs these fats to fuel the growth of your baby.
The amount of cholesterol and triglycerides in your blood will be higher than normal. For this reason, HEART UK do not recommend getting a cholesterol or triglyceride test during pregnancy because they will not reflect your normal levels.
If you breastfeed, then the levels of these fats will remain high until after your baby is fully weaned off your breastmilk. If you don't breastfeed then the levels will return to normal about three to four months after your baby is born.
Menopause marks a huge change in a woman’s body. The ovaries stop producing the hormone oestrogen and periods stop. Women often say this is the time when their bodies start to store more fat and they gain weight. So it should come as no surprise that the menopause can also mark a step wise change in cholesterol levels too.
There are three changes that can happen at the menopause to do with blood fats.
- The amount of cholesterol in the blood can rise
- The amount of HDL cholesterol often rises
- The balance of HDL cholesterol to non-HDL cholesterol may become less healthy
Cholesterol and triglyceride levels naturally increase throughout adult life and reach a peak when we are in our sixties and seventies. We don’t fully understand why, but it may partly reflect the change in our weight, activity and lifestyle as we get older.
Some less common conditions
We have two kidneys, and they're responsible for cleaning our blood by filtering out waste products which are then removed from the body as urine.
Chronic Kidney Disease (CKD). This is the name for a gradual decline in kidney function. People with CKD often have abnormal blood fats – raised LDL cholesterol and triglycerides, and lower HDL cholesterol. Heart and blood vessel diseases are common in people with CKD so statins and other cholesterol-lowering treatments are recommended if you have CKD.
Nephrotic syndrome. This happens when our kidneys become leaky. It results in protein leaking into the urine. People with nephrotic syndrome often have raised levels of cholesterol and triglycerides too.
The liver is a very important organ. It is where cholesterol and triglycerides are processed, made or broken down. Bile, a breakdown product of cholesterol, is made in the liver, stored in the gall bladder and released into the gut when we eat a meal. Its role is to help break down fat from food into small drops which can then be easily digested.
Sometimes the production of bile or its release into the gut can become blocked, for example, if gall stones develop from crystallised cholesterol. Symptoms include pain, especially after a fatty meal. The medical name for this is cholestasis, where bile is unable to flow from the liver, and it can cause blood cholesterol levels in the blood to rise.
This is a kind of arthritis caused by too much uric acid in the blood. It affect the joints and can be very painful. It happens when there is so much uric acid in the body that it forms crystals between the joints. These crystals cause the extreme tenderness, swelling and pain that people with gout usually experience.
Gout is often associated with rich food such as offal, red meat, pate, fortified wines and spirits, and too little fruit, vegetables and wholegrains. It is also linked to rise in triglycerides in the blood.
Ruling out secondary causes of high cholesterol and triglycerides
If your doctor rules out the other (secondary) causes of raised cholesterol and triglycerides listed above, then the next step is to look for other possible explanations. These include inherited (genetic) causes. Tell-tale signs of inherited high cholesterol or triglyceride include:
- close family members with high cholesterol or high triglyceride
- early heart disease in close family members
- an inherited blood fat condition in close family members.
There are over 100 genes that can affect how our bodies handle blood fats. Sometimes just one small change (or spelling mistake) in a gene is enough to raise cholesterol or triglycerides to very high levels. Sometime inheriting a number of genes that each have a small effect can add up to cause problems.
Inherited conditions that cause high cholesterol and triglycerides
Familial Hypercholesterolaemia (FH) – raised cholesterol caused by a single gene
Familial Chylomicronaemia (FCS) – triglyceride levels can be extremely high, caused by a single gene
Familial Combined Hyperlipidaemia (FCH) – this causes raised cholesterol and triglycerides
Type 3 Hyperlipidaemia – this also causes raised cholesterol and triglycerides
Polygenic Hypercholesterolaemia – raised cholesterol caused by a number of genes