Secondary causes of high blood fats

Diet and lifestyle

People are often surprised to find out they have unhealthy levels of cholesterol or triglycerides in their blood, and our Cholesterol Helpline is often asked why this could be.

Our lifelong habits, such as what we eat and how active we are, can affect our blood fats, so sometimes our lifestyles could be the cause. 

  • A diet high in saturated fat and processed foods
  • Being physically inactive
  • Being overweight or obese
  • Having a large waist circumference:
  • Smoking
  • Too much alcohol


The amount of cholesterol and triglycerides in your blood can also be affected by some medicines. To check this out, have a look at the product information leaflet which comes with your tablets.

Some medicines raise blood fats only a little and others significantly. It is important not to 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.

Here are some common medicines which are known to raise cholesterol and triglyceride levels:

  • diuretics
  • corticosteroids
  • immuno-suppressants
  • anti-retroviral drugs
  • retinoids
  • oral oestrogen
  • beta blockers
  • antidepressants
  • anticonvulsants.

If you have been prescribed any of these medicines your doctor will regularly review you. If needed, they will adjust your treatment to keep your cholesterol and or triglycerides levels in check.

Medical conditions

Your doctor will want to check what is causing your higher levels of cholesterol and triglycerides. They will check for medical conditions that are known to push them up. If one of these turns out to be the reason for your higher levels, it is important to treat it.

Here are the most common conditions that push up your levels of blood fat:

Type 2 diabetes

Undiagnosed or poorly controlled diabetes can upset the levels of triglycerides and cholesterol in your blood.

Most people know that diabetes results in high blood sugar. This poor control of blood sugar is caused by a lack of insulin - the hormone that 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.

Few people know that high blood sugar and type 2 diabetes can upset the way our bodies manage fats. People with type 2 diabetes tend to have a very characteristic patterns of blood fats:

  • 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. This is called underactive thyroid, hypothyroidism or myxoedema. It's sometimes also called Hashimoto's disease. The loss of thyroxine can be very slow, so many people don't notice it or any signs.

Here are the symptoms that some people might notice over time:

  • tiredness
  • lacking energy
  • weight gain
  • slow movements, thought and speech
  • pins and needles
  • breathlessness
  • dizziness
  • palpitations
  • hair loss especially outer third of eyebrows
  • dry skin.

An underactive thyroid is a quite common condition, especially in women between the ages of 40 and 50 years. It can raise both cholesterol and triglyceride levels, but its main effect is on our cholesterol.

Luckily it is easy to diagnose and treat, and once treated, cholesterol and triglyceride levels should return to their pre-condition 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 during pregnancy. For this reasons HEART UK do not recommend cholesterol and triglyceride tests 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 choose not to breastfeed then the levels will return to normal about 3-4 months after your baby is born.


Menopause marks a huge change in a woman’s body. It is the time when a woman’s ovaries stop producing oestrogen, her periods stop and she is no longer able to have a baby. 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 the levels of cholesterol too.

In fact there are three changes that can happen at the menopause

  • The amount of cholesterol in the blood can increase
  • The amount of HDL cholesterol often increases
  • The balance of HDL cholesterol to non-HDL cholesterol may become less healthy

Getting older

Cholesterol and triglyceride levels naturally increase throughout our adult years 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

The Kidney

We have two kidneys. They are responsible for cleaning our blood by filtering out waste products so they can be 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 lipids - raised cholesterol, triglycerides and reduced HDL cholesterol. Heart and circulatory disease is common in people with CKD so statins and other cholesterol lowering treatments are recommended. 

Nephrotic syndrome – this happens when our kidneys become leaky. It results in protein leaking into our urine. People with nephrotic syndrome often have raised levels of the blood fats – cholesterol and triglycerides – too.

The Liver

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 expelled into the gut when we eat a meal. Its role is to help breakdown fat from food into small drops that 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 in response to 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 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 that it forms crystals between the joints. It is these crystals that are responsible for the extreme tenderness, swelling and pain that people with gout usually experience.

Gout is often associated with rich living and rich food such as offal, red meat, pate, fortified wines and spirits and too little fruit, vegetables and wholegrains. It is also linked to an increase in the level of triglycerides in the blood.

Ruling out secondary causes of high cholesterol and triglycerides

If your doctor rules out other (secondary) causes of raised cholesterol and triglycerides then the next step is to look for other possible explanations. These include inherited 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
  • diagnosis of 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 increase our level of cholesterol or triglycerides to very high levels. Here are a couple of examples:

  • Familial Hypercholesterolaemia (FH) – here cholesterol levels are often double
  • Familial Chylomicronaemia (FCS) – here triglyceride levels can be extremely high

Sometime inheriting a number of genes that each have a small effect on your cholesterol and triglycerides can be enough to cause a concern. An example of this is polygenic hypercholesterolaemia.

Inherited conditions that cause high cholesterol and triglycerides

Familial Hypercholesterolaemia (FH) – an increase in cholesterol due to the influence of a single gene

Familial Combined Hyperlipidaemia (FCH) – an increase in both cholesterol and triglycerides

Type 3 Hyperlipidaemia – an increase in both cholesterol and triglycerides

Polygenic Hypercholesterolaemia – an increase in cholesterol due to the influence of a number of genes