Cholesterol levels are measured by conducting blood tests, known as lipid profiles, which indicate total cholesterol, LDL, HDL as well as triglycerides. Certain aspects that affect high levels of cholesterol can be controlled but others cannot. Major risk factors that can be controlled are highly dependent on the patient's lifestyle, such as hypertension (high blood pressure), high blood cholesterol levels, smoking, diabetes, overweight or obesity, lack of physical activity, unhealthy diet and stress.  Factors that cannot be controlled include age (simply getting older increases risk), sex (men are generally at greater risk of coronary artery disease), family history and race. All of these risk factors will significantly increase the likelihood of elevated cholesterol levels which may lead to other serious pathological outcomes such as cardiovascular disease (Hajar, 2017). 

The NHS provides the following guidelines as for values that are acceptable cholesterol levels, and are to be accepted after a cholesterol blood test. For total cholesterol desirable levels should be below 5mmol/L, whilst levels higher than 6.18 mmol/L are considered high. For LDL desirable measurements below 3mmol/L are considered acceptable. For HDL acceptable measurements are above 1 mmol/L. Finally for triglycerides values are considered acceptable if they lie below 2.3 mmol/L (National Health Service (2019)).

For persons suffering with high cholesterol levels the goal of any treatment is to significantly reduce abnormal cholesterol levels to prevent further pathological outcomes from occurring. Cholesterol control in patients may involve two different approaches: 

1. Lifestyle changes and/or

2. Medications 

Typically, both approaches are used in conjunction to achieve optimal results. (Burns et al, 2008).  Therapeutic lifestyle changes are recommended for patients with high cholesterol. The National Cholesterol Education Program (NCEP), recommends implementing changes including reducing the intake of saturated fats and cholesterol while increasing soluble fibre intake and physical activity. Optimisation of weight, moderation of alcohol consumption, and cessation of smoking are also encouraged. If drug therapy is needed, it should be used as an addition to, rather than a substitute for, therapeutic lifestyle changes (Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (2001)).

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Pharmacological treatment options are widely available. Three examples are: 

i) HMG-CoA reductase inhibitors  

ii) Fibrates 

iii) Bile Acid Sequestrants and

iv) Nicotinic Acid Derivatives

i) HMG-CoA Reductase Inhibitors, or statins, are the recommended first-line therapy for most patients. Examples include Atorvastatin, Fluvastatin and Lovastatin. Statins are similar in structure to HMG-CoA, a precursor of cholesterol, and act as competitive inhibitors of HMG-CoA reductase, the last regulated enzymatic step in cholesterol synthesis. Therefore, statins reduce the rate of synthesis of cholesterol (Toth and Banach 2019). 

ii) Fibrates (PPARa agonists) are also used to treat cholesterol. Fibric acid derivatives, or fibrates, such as gemfibrozil and fenofibrate, are agonists of the peroxisome activated receptor-α in muscle, liver, and other tissues. Fibrates can lower triglyceride levels by up to 50% and are therefore considered the first-line agents in patients with hypertriglyceridemia (Jakob et al., 2016). 

iii) Bile acid sequestrants are recommended as a second-line therapy for patients with elevated cholesterol. They bind to bile acids in the intestine, reducing absorption of cholesterol and other lipids. The resultant decrease in available cholesterol causes an increase in the number of LDL receptors, further promoting clearance of LDL from the blood (Schaiff et al., 2008). 

iv) Nicotinic Acid Derivatives such as niacin are also considered as a second line treatment option for high cholesterol levels. Niacin reduces synthesis of VLDL-C in the liver and therefore reduces LDL-C production. (Canner et al., 2005)