Cholesterol and triglycerides
Cholesterol and triglycerides are two types of fats (lipids) that are carried (and can be measured) in blood.
These fats perform essential functions, including making effective cell structures and processing vitamins A, D, E and K.
When levels are too high, they increase the risk of heart disease and stroke in HIV-negative people. This is assumed to create a similar risk for HIV-positive people and management guidelines are similar to the general population.
However, if this is a side effect of treatment for a short time, the risk may not be as great as in the general population where abnormal lipids increase and are sustained for many years.
HIV affects lipid levels. Before treatment, cholesterol becomes lower (both good and bad) and triglycerides higher.
Starting treatment with any combination will reverse these lipid effects as part of a ‘return-to-health’.
Because many HIV drugs also affect lipids this becomes a complex interaction.
Testing and monitoring
Cholesterol and triglycerides should be checked when you are first diagnosed. They should also be checked before starting or changing treatment and then three months after any change.
Routine monitoring for someone on stable treatment should then involve checking lipids every 6–12 months.
Most clinics will do this at the same time as your CD4 and viral load, but you may need to ask whether this is being done. These tests are best done fasted (on an empty stomach) so don’t eat or drink anything before your have your blood taken on those days.
Management of lipid levels should be part of an assessment of your risk for heart disease. This is also related to other risk factors, including lifestyle factors.
Lipids are first managed by diet and exercise, then by switching HIV treatment and then by using lipid lowering drugs.
Cholesterol
Total cholesterol (TC) is measured first. If these results are high then a further test will break this down into two different types of cholesterol:
- High Density Lipoprotein (HDL) is ‘good’ cholesterol. It removes fats from your arteries.
- Low Density Lipoprotein (LDL) is ‘bad’ cholesterol. It is a small molecule that carries fats from the liver to other parts of your body and can lead to heart disease.
Target levels for total and LDL cholesterol and desirable levels for HDL cholesterol and triglycerides are shown in Table 5. Target levels are lower for people who already have high cardiovascular risk due to other factors.
The TC:HDL ratio is used to determine the importance of using lipid lowering drugs, but is not used for monitoring afterwards.
Table 5: Target/desirable levels for fasted lipids (EACS guidelines)
| Total cholesterol (TC) | Less than 5.0 mmol/L (under 4.0 if high risk) |
| LDL cholesterol | Less than 3.0 mmol/L (under 2.0 if high risk) |
| HDL cholesterol | Higher than 0.9 mmol/L |
| Triglycerides | Less than 1.7 mmol/ |
Table 6: Factors that can affect cholesterol and triglycerides
| HIV | TC is lower and TG is higher before HIV treatment |
| HIV treatment | Some drugs affect cholesterol (LDL and HDL) and TG |
| Ageing | Ageing can increase cholesterol and TG |
| Smoking | Smoking increases LDL. Quitting increases HDL and reduces TG |
| Diet | Diet affects blood lipids |
| Exercise | Exercise has a good impact on lipids |
| Other infections | Other health conditions can affect lipids. |
Key: TC = total cholesterol; TG = triglycerides; HDL = high density lipoprotein (“good cholesterol”); LDL = low density lipoprotein (“bad cholesterol”); TC:HDL ratio is often more important than individual levels, with a target of 4.5 or less. Note: HDL are large particles that can pick up LDL to be broken down and eliminated from your body. LDL are small particles that have a higher risk of getting stuck and causing a blockage.
Triglycerides
Some guidelines see triglycerides (TG) as an independent risk factor for heart disease. Others state that the evidence for treating moderate triglycerides is less strong.
In the D:A:D study, most of the impact of high triglycerides was explained by other risk factors, but this still remained at +10% per year.
Although there is a lot of individual variability, target fasted levels of under 2.2 mmol/L are considered normal and of 2.2–4.4 mmol/L are borderline. Above this, the risk of heart disease increases. Levels above 11 mmol/L are considered very high and increase the risk of pancreatitis. EACS guidelines recommend a target of below 1.7 mmol/L.
Changing HIV drugs in your combination
Lipids generally improve after switching away from HIV drugs that have caused this change.
This usually involves switching from a protease inhibitor (PI) to nevirapine, raltegravir or to another PI that affects lipids less (atazanavir/r or darunavir/r). Tenofovir has a slighter better lipid impact compared to abacavir.
Nevirapine may help by increasing HDL (good cholesterol). The boosting dose of ritonavir to some extent reduces the benefits of protease inhibitors with better lipids profiles.
The debate on the impact of different strategies on reducing risk for heart disease is likely to develop and change over the next few years.
The choice of switch drugs will depend on your previous treatment history and previous history of resistance.
Diet, exercise and lipid lowering drugs
Cholesterol and triglyceride levels can sometimes be improved or controlled by reducing fat and cholesterol in your diet and by starting or increasing exercise.
Omega-3 supplements can reduce triglyceride levels. This may be much more efficient than trying to obtain sufficient quantities of omega-3 from diet alone.
For example, a 4 g daily dose Omacor, (90% omega-3 acid ethyl esters) is equivalent to 150g mackerel or 700g tuna or 210g herring or 1.1 kg cod or 280g salmon or 1.7kg eel or 850g shrimps.
If diet, supplements, and exercise are not enough, then lipid-lowering drugs (fibrates to reduce triglycerides and/or statins to reduce LDL cholesterol) are recommended.
One study showed that diet changes reduced cholesterol by 4% compared to 17% using a statin.
Lipid-lowering drugs need to be prescribed by an HIV-specialist as they can interact with HIV drugs. For example some statins should never be used and some require increased or decreased dosing when used with PIs or NNRTIs.
Studies are also looking at metformin (an insulin sensitising drug), rosiglitazone and growth hormone.
A study of HIV-positive men looking at the effects of exercise and testosterone found that testosterone significantly reduced levels of ‘good’ cholesterol (HDL). This is a concern for people with lipodystrophy who already have elevated triglycerides and ‘bad’ cholesterol (LDL).
Although muscle gain and fat loss were greater in the testosterone group, levels of good cholesterol increased in people who used exercise without testosterone, and this may be more appropriate for people with lipodystrophy.
Although anabolic steroids can increase muscle mass they can also reduce fat, and have the potential to worsen lipoatrophy and lipid levels.
Improved blood lipids have not so far shown an improvement in either fat loss or fat accumulation.
Further information