High HDL Cholesterol
High density Lipoprotein is one of the five major fat and protein particles known as lipoproteins whose role is to transport blood fats such as cholesterol and triglycerides in the blood. It is commonly referred to as the good cholesterol due to its role in removing excess cholesterol from the blood and protecting the artery wall against LDL cholesterol (bad cholesterol). Together these effects help to prevent arteries from narrowing/furring up.
Normal levels of HDL
Women usually have higher levels and should aim for a level of about 1.2mmol/L or above and men usually have levels of 1.0mmol/L or above. Most health care professionals were taught that the higher the HDL level the more protection it offers. However, many specialist doctors are now questioning this. HEART UK experts say the protective effect of HDL appears to reach its maximum when levels are around 1.5mmol/L and levels higher than this may not provide additional protection but behave more like LDL, raising the risk of developing CVD and heart problems. It is still not entirely clear at what level protection is lost, and this is also thought to possibly depend on the properties of the HDL particle that are difficult to measure.
In the first instance, doctors should consider what could cause a high level of HDL. Along with diets high in saturated fats, other causes can include exercise (usually vigorous), excessive alcohol, certain medications, genetic inheritance including Japanese ancestry, and some medical conditions such as menopause and chronic inflammatory conditions such as rheumatoid arthritis.
HCPs should encourage anyone with a high HDL level to adopt a healthy lifestyle and manage any other risk factors they may have, in particular LDL and non HDL levels. This is particularly important in women prior to and following the menopause. If someone has a family history of early heart disease and their HDL is above 3mmol/L with no obvious cause then ideally they should be referred to see a specialist at a lipid clinic for further assessment. If both total and HDL cholesterol are high (TC over 7.5mmol/L with HDL over 2.5mmol/L) then treatment decisions should be guided by levels of LDL and non HDL (bad cholesterol) rather than by the TC/HDL ratio which may be misleading.