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Hyperlipidaemia
Hyperlipidaemia

Hyperlipidaemia

Hyperlipidaemia refers to increased lipids in the blood. When we refer to blood lipids, there are 2 major types to consider: triglycerides and cholesterol.

Lifestyle factors such as diet and exercise can play a role in both of these levels. However, some other factors can cause a predominantly hypercholesterolaemia or hypertriglyceridaemia such as:

Predominantly hypercholestrolaemia

  1. Nephrotic syndrome
  2. Cholestasis
  3. Hypothyroidism

Predominantly hypertriglyceridaemia

  1. Diabetes mellitus
  2. Obesity
  3. Alcohol
  4. CKD
  5. Liver disease

The important aspect to consider with lipids is that hyperlipidaemia is a major risk factor for cardiovascular disease. This is due to atherosclerosis of coronary vessels which can lead to ischaemic heart disease, acute coronary syndromes, stroke, TIA, PAD.

We can therefore alter this risk by modifying the lipid profile:

  • Total cholesterol levels are a good predictor of CVD events.
  • Low density lipoprotein cholesterol (LDL-C) levels are directly correlated to CVS risk.
  • High density lipoprotein cholesterol (HDL-C) is inversely related to risk.

Nowadays, we can use a measure of non-HDL-C as a target for reducing CVS risk with lipid modification treatments.

Triglycerides >2.3mmol/L is also a risk factor for CVD independent of cholesterol levels.

🔍 Measuring lipid levels

When measuring lipids, we need to check full lipid profile (this includes triglycerides).

If the patient has high cholesterol levels, they may have familial hypercholesterolaemia (we will discuss this later), this needs to be considered if:

  1. Total cholesterol >7.5mmol/L
  2. Personal or family history (first-degree) of IHD before 60 years

💊 Primary prevention

The data needs to be inputted into the QRISK2 tool to predict whether you are at low, moderate or high risk of developing CVD in the next 10 years. This means that you have less than a one in ten chance of having a stroke or heart attack in the next 10 years.

  • >10% should be offered a statin according to NICE.
    • 🥇 Atorvastatin 20mg is first-line for primary risk prevention.
    • Patients should be given a period of having their CVD risk reassessed
    • They should be followed up at 3 months to repeat a full lipid profile and if the non-HDL-C has not fallen by 40% then the dose should be titrated up and increase it to 80mg. Lifestyle factors also need to be discussed.
  • If >80 years old → offer atorvastatin 20mg regardless of QRISK.
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Special situations
  • T1DM - NICE recommends considering a statin for all T1DM adults. Atorvastatin 20mg should be offered to T1DM patients who are:
    • >40 years old OR
    • Had diabetes for >10 years OR
    • Have nephropathy OR
    • Have CVD risk factors
  • CKD - atorvastatin 20mg.
    • If >40% of reduction in non-HDL-C is not achieved and the eGFR >30ml/min then we should increase the dose. A renal specialist should be consulted if eGFR <30ml/min.
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Lifestyle modifications:
  1. Cardioprotective diet
    1. Total fat intake should be <30% of the total intake.
    2. Saturated fats should be <7% of the energy intake.
    3. Cholesterol intake should be <300mg/day.
    4. Replace saturated fats with unsaturated fats.
    5. Olive oil and rapeseed oils should be preferred.
    6. Reduce sugar intake
    7. Eat 5 portions of fruit and vegetables daily
    8. Eat 2 portions of fish weekly, including a portion of oily fish
    9. Eat 4-5 portions of unsalted nuts, seeds and legumes per week.
  1. Physical activity
    1. 150 minutes of moderate-intensity aerobic exercise per week OR
    2. 75 minutes of vigorous-intensity aerobic exercise per week
    3. Muscle-strengthening activities on 2 or more days per week
  2. Smoking cessation - smokers should be encouraged to quit.
  3. Alcohol intake - should not exceed 14 units per week, spread over 3 days.
  4. Weight management - in accordance with regular guidelines.

🚨 Secondary prevention

All CVD patients should take a statin, if no contraindications are present:

  • 🥇 Atorvastatin 80mg is first-line.
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FAMILIAL HYPERCHOLESTROLAEMIA
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Familial hypercholestrolaemia is an autosomal dominant disorder that results in high levels of LDL-cholesterol → atherosclerosis and CVD.

It affects around 1 in 500 individuals.

Pathophysiology

It occurs as a result of a defect in the LDLR gene. This receptor is present on hepatocytes and allows for uptake and clearance of LDL from the plasma within the liver. However, when defective, the LDL remains in the blood and accumulates in arteries as it leads to atherosclerosis.

Most individuals are heterozygous. Homozygous FH is possible but very rare.

😷 Presentation

Familial hypercholestrolaemia may be seen in a person with premature coronary heart disease (before 60 years old).

It may also be seen incidentally with a lipid profile if the patient has a total cholesterol level >7.5mmol/L.

  • Xanthomas - found on extensor tendons (tendinous xanthoma), knees/elbows/heels (tuberous xanthoma) or xanthelasma of the eye.
Tendinous xanthoma
Tendinous xanthoma
Tuberous xanthoma
Tuberous xanthoma
Xanthelasma
Xanthelasma

🔍 Investigations and criteria

Diagnosis is based on the Simon Broome criteria and it categorises patients into either definite or possible FH:

  • Adults
    • Total cholesterol - >7.5mmol/L
    • LDL-C - >4.9mmol/L
  • Children
    • Total cholesterol - >6.7mmol/L
    • LDL-C - >4.0mmol/L
  • Definite FH - is if they meet the above criteria as well as having:
  1. Tendon xanthoma OR
  2. 1st or 2nd degree relative with FH OR
  3. DNA evidence of FH (apo B-100 or PCSK9 mutation)
  • Possible FH - if they meet the above criteria as well as having:
  1. Family history of MI <60 years in 1st degree relative
  2. Family history of MI <50 years in 2nd degree relative
  3. Family history of hypercholestrolaemia

🧰 Management

QRISK scores are not appropriate for stratifying risk in patients with FH.

  • Refer to specialist lipid clinic.
  • High-dose statin - is usually the first-line option.
  • Ezetemibe - is an alternative option.

We should also screen first-degree relatives (as they have a 50% chance of having the disorder as well).

⚠️ Women looking to conceive should discontinue the statin 3 months prior as it risks congenital defects.