HDL, LDL, non-HDL Triglycerides – Understand the Jargon
Physicians talk of the lipid profile, or lipid type while most patients want to know about their cholesterol. We really are on the same team, looking for the same goals of reducing the risk of heart and artery disease caused by abnormally levels of the types of lipids that lead to atherosclerosis. We just have different words we use. The jargon physicians use can be confusion, and lipid type is a good example. First some definitions:
Lipid: really another word for fat. A lipid is a substance that disolves in alchohol but not in water. Examples of lipids are wax, oil and other fats.
Cholesterol: a specific lipid that is used for many purposes in the body including cell membranes, hormones, vitamin D production and bile production. It consists of a sterol carbohydrate ring with specific side chains.
Lipoprotein: a particle manufactured in the liver that consists of lipids and protein that circulates in the bloodstream.
Triglyceride: molecule made up of a three carbon molecule glycerin with three long carbon chain fatty acids attached, i.e. “tri” for three + glyceride. Practically these are the fatty particles in the blood stream that did not get packaged into lipoproteins in the first pass of the blood from the gut through the liver.
HDL cholesterol: (High density lipoprotein) Think good cholesterol here. The HDL lipoprotein particle consists of more proteins which are more dense, and less lipids which are less dense, so the lipoprotein is high in density. There are several subsets of HDL, but in general a high HDL level is good. HDL cholesterol functions in part to remove cholesterol from places it does not belong and return it to the liver to be repackaged and better used.
LDL cholesterol: (Low density lipoprotein) Think bad cholesterol here. A lipoprotein that is higher in lipid and lower in protein making it low density. In general high levels of LDL cholesterol are not good, as they increase the risk of atherosclerosis and heart disease. LDL cholesterol is the primary vehicle for carrying cholesterol in the blood stream. When present in large amounts cholesterol is often put where it can cause harm, like on the lining of blood vessels.
CRP: (C-reactive protein or hsCPR for highly sensitive CRP) is a marker of inflammation, and is used sometimes to assess risk of heart disease when the cardiovascular risk based on the rest of the lipid measurements and the other risk factors do not lead to a clear decision on lipid management.
Non-HDL cholesterol: This is simply calculated by subtracting the HDL cholesterol level from the total cholesterol level. non-HCL cholesterol is a secondary target for treating lipids, after the LDL goal is met.
Direct LDL: usually the LDL level is calculated using the formula:
Total Cholesterol – HDL cholesterol – Triglycerides/5 = LDL cholesterol
This formula is quite accurate except when the triglyceride level is over 400-500. High triglyceride levels make this calculation less accurate, so in those cases a more expensive test is used to measure the LDL cholesterol directly.
Physicians use these numbers along with a patients other risk factors to decide on whether to treat them with medication for abnormal lipid measurements. In general the more risk factors for heart disease a patient has the more likely they are to warrant medication treatment.
The risk factors recommended by the National Institute of Health (through the NHBLI) for this decision making include:
Table 3. Major Risk Factors (Exclusive of LDL Cholesterol) That Modify LDL Goals*
- Cigarette smoking
- Hypertension (BP ³140/90 mmHg or on antihypertensive medication)
-Low HDL cholesterol (<40 mg/dL)†
-Family history of premature CHD (CHD in male first degree relative <55 years; CHD in female first degree relative <65 years)
-Age (men ³45 years; women ³55 years)*
* In ATP III, diabetes is regarded as a CHD risk equivalent.
† HDL cholesterol ³60
(table from the NIH site)
The levels of cholesterol are broken down into categories:
Table 2. ATP III Classification of LDL, Total, and HDL Cholesterol (mg/dL)
LDL Cholesterol
<100 Optimal
100-129 Near optimal/above optimal
130-159 Borderline high
160-189 High
>190 Very high
Total Cholesterol
<200 Desirable
200-239 Borderline high
³240 High
HDL Cholesterol
<40 Low
>60 High
(table from the NIH site)
The recommendations for goal LDL cholesterol are as follows:
Three Categories of Risk that Modify LDL Cholesterol Goals
Risk Category LDL Goal (mg/dL)
CHD and CHD risk equivalents <100
Multiple (2+) risk factors* <130
Zero to one risk factor <160
* Risk factors that modify the LDL goal are listed in Table 3
(from the NIH site)
Using these recommendations a woman age 67 who does not smoke, has a BP < 140/90 on no blood pressure medication, has an HDL cholesterol of 38, and has no coronary heart disease in her mother, father, or siblings would have 2 risk factors (age plus low HDL cholesterol) making her goal LDL <130.
Similarly a man age 40 who smokes, is on BP medication, and whose father had his first heart attack at age 50 with an HDL of 33 would have three risk factors (smoking, blood pressure and family history) so his goal LDL cholesterol would be <130 unless his Framingham calculated risk of developing Coronary disease in the next 10 years is >20%.
Here is a link to the calculator provided by the NIH to calculate Framingham Risk:
Using this calculator the 10 year risk of the man above would be 22% if his current systolic BP was 130 on medication, so he falls into the CHD equivalent category and has a goal of <100 for LDL cholesterol.
Treating LDL cholesterol is usually pretty straightforward. We try to get patients to eat a diet low in total fat and saturated fat (primarily animal fat) to avoid trans fatty acids, and to lose weight. If this is not adequate we usually add a medication in the statin family. Many generic statins are available and can keep costs of treatment fairly low, and most patients tolerate statins well. Some patients do not and red yeast rice is sometimes tolerated by those patients. It has a statin-like effect. Statins can lower LDL cholesterol by 25-55% in most patients. If statins are not tolerated, or if you are a woman who may become pregnant (absolute contraindication to statins) then other medications are sometimes used.
Treating low HDL cholesterol is more difficult, and often slow release niacin is used for this purpose, but it is sometimes difficult to tolerate because of flushing and itching side effects.
Treating triglycerides is important if they are extremely high. Levels >500 can put you at risk for pancreatitis, and need to be treated. Levels between 150 and 500 are suboptimal, and are sometimes treated.
In general the goals for non-HCL cholesterol are the LDL goals + 30.
Hopefully this has been helpful in understanding your lipid profile. If you have suggestions for improvement, or other comments, please leave them in the comments section below.
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Other articles you may enjoy:
Diabetes Mamagement: It’s Not All About Blood Sugars
VBAC and Home Birth
Kenny Lin MD is a family physician who posts regularly at Common Sense Family Doc. He always has well researched and thought out opinions, and this is a good example of his writing, first posted at his site on July 29, 2010.
VBAC and home birth: evaluating the evidence
Thanks to a recent pronouncement from the American College of Obstetricians and Gynecologists, my two-year old daughter, who arrived via a vaginal birth after Cesarean section (VBAC), may not be a medical rarity for much longer. In a previous post, I discussed possible causes for the steep 15-year decline in the percentage of U.S. women who have delivered a child vaginally after a previous Cesarean birth (currently fewer than 1 in 10). In March, at a conference held at the National Institues of Health in Bethesda, Maryland, an expert panel concluded that the scientific evidence did not support ACOG’s existing recommendation that surgical and anesthesia personnel be “immediately available” during a trial of labor. However, they found evidence that this restrictive requirement had caused many hospitals without 24-hour availability of these services to discontinue VBAC entirely.
To its credit, last week ACOG released an updated version of the guideline that states that a trial of labor is a reasonable option for the vast majority of women who desire a vaginal delivery after a previous Cesarean, including those who have had more than one prior Cesarean and those carrying twins. While continuing to assert that mothers and babies are best served by access to emergency resources, they add: “Respect for patient autonomy also argues that … [an institutional no-VBAC policy] cannot be used to force women to have cesarean delivery or to deny care to women in labor who decline to have a repeat cesarean delivery.” Amen.
Now I’ll to turn to another controversial maternity care topic: home birth. The subject of a widely viewed 2008 documentary and Time Magazine story, out-of-hospital births represented less than 1 percent of all births in the U.S. in 2005, according to government researchers. A recent meta-analysis of previous studies comparing planned home and planned hospital births that concluded that the former was “associated with a tripling of the neonatal mortality rate” elicited a variety of reactions from health professionals in the U.S. and abroad, ranging from ACOG’s reiterating its opposition to home births to calls for more research by the American College of Nurse Midwives and the UK’s Royal College of Obstetricians and Gynecologists.
I agree that more research is needed. But as for the analysis itself, there are at least two reasons to question whether it should cause many (or any) women to reconsider their home birth plans. First, while “tripling” in neonatal deaths sounds scary, this is a relative rather than an absolute difference in risk. Reading the fine print, neonatal death occurred in 0.15 percent for planned home and 0.04 percent for planned hospital births. That’s an absolute risk difference of just 0.11 percent, or about 1 extra death for every 1000 births. This difference is very close to the small increased risk of neonatal death during attempted VBAC versus repeat Cesarean section (0.8 extra deaths for every 1000 births), which ACOG has acknowledged should be a mother’s choice.
Second, all but 3 of the 12 studies included in the meta-analysis were conducted prior to the year 2000, in populations with much lower Cesarean rates than in the U.S. Overall, only 9.3% of women in the planned hospital birth groups had Cesarean deliveries – a far cry from the 32% that currently occur in the U.S. So while this study’s results are most applicable to countries in other parts of the world that have Cesarean rates of 10% or less, it’s not clear if it captured the maternal complications that invariably result from doing 3 times as many surgeries.
The bottom line? The available evidence indicates that planned home birth is no riskier for babies, compared to planned hospital birth, than is attempting VBAC compared to choosing a repeat Cesarean delivery.