Lipids are fats in the blood, mainly Cholesterol and Triglycerides. They’re made by the body, and are essential for life. The problem is when we have too much. Blood tests measure the following Lipids:
- Total Cholesterol (all cholesterols together)
- Low-density lipoproteins (LDL), “bad cholesterol,” which causes heart disease if there’s too much
- High-density lipoproteins (HDL), “good cholesterol,” which protects against heart disease if there’s a lot, & is bad for the heart if there’s too little
- Very-low-density lipoproteins (VLDL), we don’t know what effect these really have
- Triglycerides, another type of fat (see below for its dangers)
A committee of the American Heart Association (AHA) has recommendations for healthy levels of cholesterol, and when to use medications. Diet and exercise are fine treatments, but in research studies using very strict diets, where investigators measure every little bit of cholesterol eaten, people can only lower their cholesterol 15% at most. So when levels are high enough, drug therapy is necessary. The vast majority of our lipid levels are determined genetically.
Medically, our main interest is in the LDL, since if it’s too high, we can lower it with “statin” drugs. AHA guidelines have changed over the years, and the most recent ones of 2013 (revised 2016) leave out numbers. They calculate risk of heart attack in the next 10 years based on age, gender, blood pressure, diabetes, and cigarette smoking — if the risk is >7.5%, a statin is recommended. This is because statins help prevent heart attacks in ways we don’t understand, unrelated to cholesterol levels.
Lots of people think AHA over-recommends treatment, since by a certain age, everyone in the country / world should be taking a statin. European professional organizations use risks higher than 7.5% to recommend medication. The AHA calculator can be found on-line: http://www.cvriskcalculator.com/
FYI — In the old days (before 2013), we paid attention to numbers, and many clinicians still think about them. The levels below were considered healthy; if a patient’s were just a little too high, we used diet & exercise, but otherwise, statins. There’s a range here; the lower numbers were suggested in 2001, but many of us thought there was too much representation of the pharmaceutical industry on that panel, and went (or still go) by the higher values.
As per numbers, Fasting LDL were recommended to be lower than:
- 130-160 for most people
- 100-130 for smokers, people with hypertension or strong family history of heart attacks
- 70-100 for people with diabetes
- 70 for anyone who has known coronary artery disease
For non-fasting tests, subtract Total Cholesterol minus HDL. Then subtract another 30, and use the numbers above. The current AHA calculators also incorporate HDL, which may be good. As noted, low HDL levels represent a significant risk for heart disease; >40 is healthy, for women after menopause it should be >50. But there’s no way to increase HDL. A drug was invented a few years ago, worked very well, but some people died of liver failure (it never reached market).
Triglycerides are different. Normal levels are <150-200, and higher ones may contribute to heart disease. But nobody’s ever proved well that lowering levels prevents heart attacks, so it may not be worth worrying about. Personally, I don’t treat my patients with minimal elevations. Very high triglycerides can cause fatal pancreatitis, but levels need to be >500 to be dangerous, and are almost always >1,000. Such levels are always due to genetics (heredity). The blood test for Triglycerides must be done after a 10-12 hour fast, or it won’t be accurate.