To the Rescue
Thyroid Supplementation for Heart Health

re you feeling sort of sluggish? Fatigued? Depressed? Has your mind lost its usual razor's edge? What about some more obvious things, such as weight gain, constipation, or aching joints? Do you have low blood pressure or high cholesterol? Has your libido declined? Do you have dry skin, brittle nails, or hair loss? Are you overly sensitive to cold?

All of these symptoms can arise, individually, from a great variety of causes, and most can be so subtle and slow to develop that one barely notices them. But if some combination of them rings a bell in you that says, "That sounds like me," then you could be one of the millions of people with an underperforming thyroid gland, a condition often called "low thyroid."

Now suppose you had some of these mild symptoms, which are not incapacitating, certainly, but not welcome either. If you thought they might be due to low thyroid, you could try a natural thyroid supplement to see if it helped. Many people do - and it often does. Or you could go to the doctor to get checked out. Chances are that, after an all-too-brief interview and examination, the doctor would order lab tests. But what if the tests came back negative? It's likely that more tests would be ordered, this time for things less likely to be wrong with you, and therefore even more likely to come back negative (except, of course, for the invoice, where negatives are not allowed). At that point you would probably feel you were being told that: (1) "it's probably all just in your head" or (2) if you're getting on in years, "it's part of the normal aging process - don't worry about it." When you hear that, it's time to worry - about your health and maybe about finding a better doctor.

HOW SUBCLINICAL THYROIDISM GETS OVERLOOKED
That remark about "the normal aging process" is modern medicine's ace in the hole. What a convenient, accommodating rug under which to sweep the beasties that don't show up in lab tests and that the doctors are too busy to examine thoroughly because of the efficiency with which their time is "managed" by the HMO bean counters. Even if they had the time, however, and assuming they had the inclination, most modern doctors have not received much training in the classical art of physical diagnosis - ferreting out the causes of subtle and often ambiguous symptoms by the hands-on application of their medical knowledge and their powers of observation. With medical schools so devoted to preaching the twin gospels of lab tests for diagnosis and pharmaceuticals for therapy, there doesn't seem to be much room left for the traditional principles of medical practice.

The upshot is that your symptoms may go undiagnosed as what they actually represent: subclinical hypothyroidism, or low thyroid activity that nonetheless falls within the "normal" range - albeit probably low-normal - in lab tests. And if you have symptoms but are not even aware of them, it is often possible for a really good doctor to spot them through careful physical examination and a close look at your medical history.

WHY DETECTING IT IS SO IMPORTANT
Why all this is important - and why you should worry - is because maintaining good thyroid health is even more vital than had previously been thought. That is the conclusion reached recently by a group of medical researchers at the Erasmus University Medical School in Rotterdam, The Netherlands, who studied the relationship between subclinical hypothyroidism and cardiovascular disease in postmenopausal women.1 They found a strong link.

It had long been known that overt hypothyroidism, in which the lab tests are definitely abnormal, is linked to various aspects of heart disease, but there was little evidence that this was also true of the subclinical version of this condition. What we now know, from the Dutch study, however, is that ". . . subclinical hypothyroidism is highly prevalent in elderly women and is strongly and independently associated with aortic atherosclerosis and myocardial infarction."

Before we see how the researchers came to this depressing conclusion, let us quickly review the thyroid gland and what happens when it's not functioning up to par. (For a more detailed discussion, see The Importance of Thyroid Supplementation Nov. 1999.)

THE THYROID GLAND
Residing in the front of your neck, your thyroid gland presides, like a ringmaster, over a number of interrelated acts being performed throughout your body. On demand, it releases the hormone thyroxine, whose primary role is to regulate the body's metabolism - the panoply of chemical reactions by which some substances are broken down to yield energy for vital processes while other substances, necessary for life, are synthesized.

Overt hypothyroidism (also called thyroid deficiency syndrome) is a deficiency of thyroxine, and probably of the other hormones secreted by the thyroid gland. (These hormones have the shorthand designations T1, T2, T3, and T4, the last of which is thyroxine.) The bad news is that this deficiency can cause the spectrum of symptoms described above. Worse, however, is that it predisposes to much more serious ailments, such as heart disease, in part through its cholesterol-elevating effect.

The good news, though, is that hypothyroidism is easy to treat by administering T4, either as the pure chemical or in the form of whole thyroid glandular extract. There is much to be said for the latter approach, because the extract contains all four of the thyroid hormones produced naturally, in their biologically normal proportions. Mother Nature created them all for her own reasons, and even if we don't understand all the reasons, we are wise to follow her lead rather than try to outguess her by focusing on just T4, which is the sole active substance in most prescription thyroid medications.

SUBCLINICAL HYPOTHYROIDISM IS LINKED TO ATHEROSCLEROSIS AND HEART ATTACKS
In the Dutch study, the researchers adopted a definition of subclinical hypothyroidism based not on abnormal T4 levels, but rather on an elevated level of thyrotropin, a hormone secreted by the pituitary gland. Also known as thyroid-stimulating hormone (TSH), it regulates the thyroid gland's production of T4. If the TSH level rises beyond a certain point even though the T4 level remains within its normal range, that is an indication that thyroid function is being compromised.

Based on this criterion, the Dutch researchers examined a random sample of 1149 postmenopausal women (mean age 69) selected from Rotterdam for a study designed to determine whether there is an association between subclinical hypothyroidism and heart disease in such women. The women were carefully examined to eliminate potential sources of error in the study. When those who had overt hypothyroidism or hyperthyroidism (overactivity of the thyroid gland) or who were taking certain medications were screened out, the researchers were left with 975 subjects.

Of the original 1149 women studied, 124, or 10.8%, were found to have subclinical hypothyroidism. This figure agrees well with those reported in several studies in other countries,2-4 suggesting that the Dutch sample was representative of the general population.

Overall, the women affected did not differ from normal women in age, body mass index, blood pressure, or smoking status, nor in measures of various blood components, but they did have significantly lower levels of total cholesterol, and borderline significantly lower levels of HDL ("good") cholesterol, in age-adjusted comparisons.

The cholesterol results seem paradoxical in light of the fact that these same women were found to have a greater prevalence than normal of aortic atherosclerosis (a buildup of fatty plaque in the aorta) and of myocardial infarction (heart attack). The researchers speculate that other lipids, such as LDL ("bad") cholesterol and triglycerides, may be responsible for the association between subclinical hypothyroidism and heart disease, but those factors were not measured in this study.

Based on exhaustive statistical analysis of the baseline (beginning of the study) characteristics of all the women, the authors came to the conclusion that both aortic atherosclerosis and myocardial infarction are significantly more prevalent among elderly women who have subclinical hypothyroidism than among those who do not. They estimated that this silent disorder was the cause of 14% of all the heart attacks in the study sample, ranking only slightly below such well-known risk factors as high blood pressure, high cholesterol, diabetes, and smoking.

There are numerous competing theories regarding the mechanisms by which subclinical hypothyroidism may contribute to heart disease, but one interesting facet of the Dutch study is that it showed that the disorder is independently associated with both aortic atherosclerosis and myocardial infarction. These two manifestations of heart disease are, of course, related to each other: it is well known that atherosclerosis is a predisposing factor for heart attacks.

IT IS WISE TO BE TESTED
What does it all mean? Simply this: the risk factors now known to be associated with subclinical hypothyroidism are too great to be ignored. Whereas the risk of its developing into overt hypothyroidism is ameliorated somewhat by the relative ease with which that disease can be treated (via supplementation), the same cannot be said for the cardiovascular risk, which is far more ominous.

It is wise, therefore, to ensure that your thyroid is functioning properly, particularly if you are a postmenopausal woman (but men and even teenagers can be affected by subclinical hypothyroidism too) or if there is a history of thyroid disorders in your family.

THYROID SUPPLEMENTATION IS FOUND TO PROTECT AGAINST ATHEROSCLEROSIS
The importance of maintaining good thyroid health is further underscored by the results of a study conducted at the medical school of Dalhousie University, Halifax, Nova Scotia.5 There, cardiologists examined the effects of the adequacy of thyroid hormone replacement therapy on the progression of atherosclerosis in hypothyroid patients. They used the technique of coronary angiography - examination of the coronary arteries using x-rays following the injection of a radiopaque substance - to evaluate the condition of the arteries, and they evaluated the patients' thyroid therapy to determine whether it was adequate or inadequate to control their hypothyroidism.

In their study of ten hypothyroid, atherosclerotic patients, the researchers found a strong correlation between inadequate thyroid therapy and the progressive atherosclerotic narrowing of the coronary arteries, over a two-year period. By contrast, they found that adequate thyroid therapy appeared to be protective against further progression of the atherosclerosis. While admitting that larger studies are needed to confirm these findings, they believe that their results suggest a beneficial effect of thyroid hormone therapy on coronary atherosclerosis. We might add that because atherosclerosis is a predisposing factor for heart attacks, these benefits could literally be life-saving.

The authors state that "Hypothyroidism in the elderly is not uncommon, and its prevalence is likely to increase in the future. Because atherosclerosis is also common in this age group, those with inadequately treated or unrecognized hypothyroidism will continue to develop atherosclerotic vascular disease, either as an independent, coexistent problem or as a secondary manifestation of hypothyroidism."

PROTECT THYROID FUNCTION AND MORE
Even if you have no thyroid disease, overt or otherwise - and provided that you have no overt endocrine disease of any kind - you may benefit from thyroid supplements designed to help rejuvenate the entire endocrine system (not just the thyroid) and thus to help prevent age-related decline.

That is a bodily system well worth nourishing, especially if it might help to inhibit the progression of atherosclerosis.

References

  1. Hak AE, Pols HAP, Visser TJ, Drexhage HA, Hofman A, Witteman JCM. Subclinical hypothyroidism is an independent risk factor for atherosclerosis and myocardial infarction in elderly women: the Rotterdam Study. Ann Int Med 2000 Feb15;132:270-8.
  2. Tunbridge WM, Evered DC, Hall R, Appleton D, Brewis M, Clark F, et al. The spectrum of thyroid disease in a community: the Wickham Survey. Clin Endocrinol (Oxf) 1977;7:481-93.
  3. Sawin CT, Castelli WP, Hershman JM, McNamara P, Bacharach P. The aging thyroid. Thyroid deficiency in the Framingham Study. Arch Int Med 1985;145:1386-8.
  4. Parle JV, Franklyn JA, Cross KW, Jones SC, Sheppard MC. Prevalence and follow-up of abnormal thyrotrophin (TSH) concentrations in the elderly in the United Kingdom. Clin Endocrinol (Oxf) 1991;34:77-83.
  5. Perk M, O'Neill BJ. The effect of thyroid hormone therapy on angiographic coronary artery disease progression. Can J Cardiol 1997;13(3):273-6.

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