Hello,
Thanks for asking your question.
1) Which is the biggest indicator of problems or risk?
* The Total Cholesterol number or,
* The ratio of LDL/HDL
Both are associated with cardiac risk. However, the LDL/HDL ratio is
a bigger indicator. The components of a measured total cholesterol
(LDL, HDL, triglycerides) includes HDL ("good" cholesterol) which
correlates inversely with cardiac risk.
From Best Practice of Medicine:
"Although useful in screening large populations for dyslipidemias,
serum cholesterol cannot be considered the sole measure of risk for
CHD attributable to serum lipids. This is based on our current
understanding of lipoprotein cholesterol subfractions and the
availability of standardized laboratory methods to measure them in
clinical practice. Serum total cholesterol tends to index
low-density-lipoprotein (LDL) cholesterol, which varies directly with
CHD risk (Figure 6) and is considered atherogenic.
High-density-lipoprotein (HDL) cholesterol varies inversely with CHD
incidence and is considered anti-atherogenic or protective."
http://merck.micromedex.com/bpm/bpm.asp?page=CPM02CA335§ion=report&ss=2
Here is a definition of the LDL/HDL ratio:
"Another ratio is LDL/HDL. The LDL/HDL ratio is actually a more pure
ratio than total cholesterol/HDL. Because LDL is a measure of bad
cholesterol and HDL is a measure of good cholesterol, whereas the
total cholesterol is the sum of HDL, LDL, and the VLDL. Yes, adding up
the HDL, LDL and VLDL makes up the total cholesterol measurement."
http://my.cardiovalens.com/featured/featuredisplay.asp?featureid=155
The data from studies suggests that the LDL/HDL ratio is more
predictive of cardiac risk:
"Data from the Lipid Research Clinics and the Framingham Heart Study
suggest that the total cholesterol (or
LDL-cholesterol)-to-HDL-cholesterol ratio may have greater predictive
value for CHD than serum total or LDL-cholesterol . . . In contrast,
serum total or LDL-cholesterol did not add independent predictive
value to the ratio." (1)
2) How is the Total Cholesterol number calculated?
This is derived from the Friedewald formula for LDL cholesterol:
LDL-cholesterol = Total cholesterol - (triglycerides/5) -
HDL-cholesterol
Thus, doing some basic algebra:
Total cholesterol = LDL-cholesterol + HDL-cholesterol +
(triglycerides/5)
3) What may be some valid reasons for why a Total Cholesterol Number
(say
286 but an extremely low ratio for LDL to HDL, say 1.2, a ratio that
places
a woman in the 1/2 average risk range) might cause an insurance
company to either rate up or deny coverage - based on the Total
number without regard to the low risk ratio?
I cannot say for sure since I don't work for any insurance companies,
but I can hypothesize it is because of the triglycerides. What is not
accounted for in a LDL/HDL ratio is the triglycerides (i.e. fat
content in the blood). Even though the ratio is low, the fact that
the total cholesterol is high suggests that the triglycerides are
high. High triglycerides are a negative predictor of cardiac risk.
From UptoDate:
"Hypertriglyceridemia is associated with an increased risk for
cardiovascular disease . . . In the Physician's Health Study, the risk
of myocardial infarction (MI) was highest among men with the highest
tertile for both triglyceride and the TC/HDL-C ratio." (2)
From Best Practice of Medicine:
"Data from several studies, including the Framingham Study, suggest
that serum triglycerides may be important predictors for CHD in men or
women, but not consistently in both sexes. Despite these observations,
the current consensus holds that elevated levels of serum
triglycerides represent a risk marker for obesity, glucose
intolerance, and low HDL levels, all of which confer risk for CHD and,
to the extent possible, deserve preventive attention."
http://merck.micromedex.com/bpm/bpm.asp?page=CPM02CA335§ion=report&ss=2
Please use any answer clarification before rating this answer. I will
be happy to explain or expand on any issue you may have.
Thanks,
Kevin, M.D.
Internet search strategy:
No internet search engine was used in this research. All sources were
from objective physician-written and peer reviewed sources.
Bibliography:
1) Kinosian, B, Glick, H, Garland, G. Cholesterol and coronary heart
disease: Predicting risks by levels and ratios. Ann Intern Med 1994;
121:641.
2) Stampfer, MJ, Krauss, RM, Ma, J, et al. A prospective study of
triglyceride level, low-density lipoprotein particle diameter, and
risk of myocardial infarction. JAMA 1996; 276:882.
Links:
Best Practice of Medicine - Cardiac Risk Factors
http://merck.micromedex.com/bpm/bpm.asp?page=CPM02CA335§ion=report&ss=2
Cardiovalens.com - Cardiac Risk Factors
http://my.cardiovalens.com/featured/featuredisplay.asp?featureid=155 |
Clarification of Answer by
kevinmd-ga
on
31 Jan 2003 14:48 PST
Hello,
Thank you for your kind words.
One uncommon scenario that I neglected to mention that could cause a
low LDL/HDL ratio and high total cholesterol is your case. That would
be an HDL ("good cholesterol") so high that it causes the total
cholesterol to rise. An HDL of 120 is extrodinarily high - one if the
highest I've seen. If you look at the formula:
Total cholesterol = LDL-cholesterol + HDL-cholesterol +
(triglycerides/5)
Although it is more common that a rise in triglycerides would cause
the total cholesterol to rise, you can see how a high HDL cholesterol
would lead to a high total cholesterol.
A HDL of 60 is already considered high, above 40 mg/dL is normal. The
cardiovascular risk drops approximately 10-20 percent every 5 mg/dL
the HDL is above 40. Note that the HDL in your case is 120 - it is
literally off the scale.
1) "Is a triglyceride of 67 high?"
No. Normal triglyceride level is less than 150.
2) "Can diet or exercise make changes that would improve the numbers
and her health risk?"
Yes. Lifestyle modifications are effective in treating triglycerides
and LDL. From UptoDate:
"Hypertriglyceridemia is often induced or exacerbated by secondary,
potentially correctable disorders. Thus, nonpharmacologic
interventions such as weight loss in obese patients, aerobic exercise,
avoidance of concentrated sugars and medications that raise serum
triglyceride levels, and strict glycemic control in diabetics should
be the first-line of therapy.
All patients with high LDL cholesterol should undergo lifestyle
modifications (therapeutic lifestyle changes as stated in ATP III)
such as reductions in dietary total and saturated fat, weight loss in
overweight patients, aerobic exercise, and plant stanols/sterols." (1)
3) If a woman already eats carefully and exercises is there something
that else thatcould or should be done?
The next step would be medication. You may want to refer to the
National Cholesterol Education Program Guidelines for more
information:
http://www.nhlbi.nih.gov/guidelines/cholesterol/index.htm
4) Does you research even show that something should be attempted to
bring down the total cholesterol number when the LDL/HDL Ratio is low?
In most cases, the reason the total cholesterol is high becasue of the
LDL ("bad" cholesterol) or triglycerides is high. Treatment in those
cases would involve improved diet, increased exercise, and perhaps
medication. In this case, the HDL ("good" cholesterol) is causing the
high total cholesterol. When the HDL is this high, it is acceptable
to tolerate a high total cholesterol.
Looking at the profile you provided, the LDL is 152. The target level
is dependent on risk factors (i.e. < 100 for diabetes and heart
disease, <130 for 1-2 risk factors, <160 for no risk factors).
Lowering LDL via diet and exercise would lower total cholesterol.
5) I would like to add $15 because I have just asked you to pursue
several other related questions. I will try to figure out how to do
this.
Thank you for your generosity - this can be accomplished via the "tip"
function when the answer is rated. I would strongly discussing this
lipid profile with your physician if the insurance company is raising
your rates because of these results.
Thanks,
Kevin, M.D.
Bibliography:
1) Rosenson, R. Treatment guidelines for hypercholesterolemia.
UptoDate, 2002.
|
