A BASELINE MEASURE OF YOUR DISEASE
AND RISK PROFILE
Part 2
Continued: TESTS
Cardiac
Risk Factors
This is a battery of tests that measure substances in the blood that
may predispose you to arterial and heart disease.
Important note: Sometimes, months to years after a patient has experienced
normal or near-normal blood sugars and resultant improvements in the
cardiac risk profile, we might see deterioration in the results of such
tests as those for LDL, HDL, homocysteine, and lipoprotein(a). All too
often, the patient or his physician will blame our diet. Inevitably,
however,we find upon further testing that his thyroid activity has declined.
Hypothyroidism is an autoimmune disorder, like type 1 diabetes, and
is frequently inherited by diabetics and their close relatives. It can
appear years before or after the development of diabetes and is not
caused by high blood sugars. In fact, hypothyroidism can cause a greater
likelihood of abnormalities of the cardiac risk profile than can blood
sugar elevation. The treatment of a low thyroid condition is oral replacement
of the deficient hormone(s)—usually 1 pill daily. The best screening
test is free T3. If this is low, then a full thyroid test profile should
be performed. Correction of the thyroid deficiency inevitably corrects
the abnormalities of cardiac risk factors that it caused.
Lipid profile.
This profile measures fatty substances (lipids) in your blood and includes
total cholesterol, HDL (high-density lipoprotein), triglycerides, and
direct LDL (low-density lipoprotein). Other cardiac risk factors (discussed
below) include C-reactive protein, fibrinogen, lipoprotein(a), and homocysteine,
and may be more predictive. Abnormalities
of these tests are frequently treatable and tend to improve with normalization
of blood sugars.
These tests should be performed after you have fasted for at least
8 hours. The easiest thing is to have them scheduled in the morning.
If you haven’t fasted before the test, the results will be difficult
to interpret.
Maybe you’ve heard of “good” cholesterol and “bad”
cholesterol?
Well, this is why a reading for total cholesterol by itself won’t
necessarily reflect cardiac risk. Most of the cholesterol in our bodies,
both good and bad, is made in the liver; it does not come from eating
so called “heart attack foods.” If you’ve eaten a
meal that’s high in cholesterol, your liver will adjust to make
less of the “bad” cholesterol, LDL. Serum triglyceride levels
can vary dramatically after meals, with high carbohydrate meals causing
high triglyceride levels. Some people—because they’re obese
or have high blood sugars or are genetically predisposed—make
more or dispose of less LDL than they should, which can put them at
a higher risk for cardiac problems. High levels of LDL increase the
risk of heart disease, which makes LDL the “bad” cholesterol.
HDL, on the other hand, is a lipid that reduces the risk of heart disease
and is the “good” cholesterol. So it is the ratio of total
cholesterol to HDL (total cholesterol ÷ HDL) that is significant.
You could have a high total cholesterol and yet, because of low LDL
and high HDL, have a low cardiac risk. Conversely, a low total cholesterol
but with a low HDL would signify increased risk. Recently, as more has
become known about cholesterol, research has shown that LDL occurs in
at least two forms—small, dense LDL particles (the hazardous form)
and large, buoyant LDL particles. Although small, dense LDL is not,
at this writing, being measured by commercial labs, it can be estimated
by dividing the triglyceride measure by the HDL measure. This ratio
is even more informative of cardiac risk than the traditional cholesterol
÷ HDL ratio.
The only truly accurate measure of LDL is the direct LDL test. The
customary, indirect measure of LDL is estimated mathematically andcan
result in values that are grossly in error. Direct measurement of LDL,
however, may cost more than all the rest of your lipid profile.
Also important to remember is that—as we will discuss in Chapter
9—fats and cholesterol in the diet do not cause high-risk lipid
profiles in most people. On the other hand, diabetics tend to have lipid
profiles that reflect increased cardiac risk, if their blood sugars
have been elevated for several weeks or months.
Homocysteine (fasting)
Recently discovered as a (nonlipid) cardiac risk factor is homocysteine.
This is an amino acid that tends to be elevated in poorly controlled
diabetes and in individuals with kidney impairment or folic acid, vitamin
B-12, or vitamin B-6 deficiency.
Thrombotic risk profile
This profile includes levels of fibrinogen, C-reactive protein, and
lipoprotein(a). The latter two are “acute phase reactants,”
or substances that reflect ongoing infection and other in-flammation.
These three substances are associated with increased tendency of blood
to clot or form infarcts (blockages of arteries) in people who have
had sustained high blood sugars.
In the cases of elevated fibrinogen or lipoprotein(a), there is, additionally,
often an increased risk of kidney impairment or retinal disease. Obesity,
even without diabetes, can cause elevation of C-reactive protein. In
my experience, all these tests are more potent indicators of impending
heart attack than the lipid profile. Treatments are available for elevations
of each of these. Blood sugar normalization will tend to reverse most
of these elevations over the long term. Fibrinogen can be elevated by
kidney disease, even in the absence of elevated blood sugars. It will
tend to normalize if kidney disease reverses. Lipoprotein(a) will also
tend to normalize somewhat by blood sugar normalization, although your
genetic makeup (and low estrogen levels in women) can play a greater
role than blood sugar.Abnormally low thyroid function is a common cause
of low HDL and elevated LDL, homocysteine, and lipoprotein(a).
Serum transferrin saturation, ferritin, total iron binding
capacity (TIBC)
These are all measures of total body iron stores, which tend to be more
elevated in men than in premenopausal women. Iron is vital, but it is
also potentially dangerous. Levels that are too high can indicate a
cardiac risk, cause insulin resistance, and are a risk factor for liver
cancer. I will discuss insulin resistance at length in Chapter 6. Higher
iron levels are more likely in men than in premenopausal women because
of blood (iron) loss during menstruation. (This is why I recommend iron-enhanced
vitamin supplements only for those with an established need.) Iron levels
that are too low (iron deficiency anemia, which is more common in premenopausal
women) can cause an uncontrollable urge to snack, which in turn can
lead to uncontrollable blood sugars. Both high and low iron stores can
easily determined
and readily treated.
Part One,
Part Three
We would like to thank the publisher Little Brown and Company and
Dr. Richard K. Bernstein, for allowing us to provide excerpts from Diabetes
Solution.
Copyright © 2003 by Richard K. Bernstein, M.D.
All rights reserved. No part of this book may be reproduced in any form
or by any electronic or mechanical means, including information storage
and retrievalsystems, without permission in writing from the publisher,
except by a reviewer who may quote brief passages in a review.
Author’s Note
This book is not intended as a substitute for professional medical care.
The reader should regularly consult a physician for all health-related
problems and routine care.
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