Since the publication of the extraordinary HUNT Study relating the entire spectrum of thyroid function and heart issues, I have been vigorously and systematically examining thyroid function in numerous patients.
While there's no news in relating flagrant low thyroid function with triggering heart disease in several forms, the cut-off between low thyroid and normal thyroid has been a matter of dispute for decades.
In the early 20th century, low thyroid function wasn't diagnosed until someone gained 40 lbs, displayed extravagant amounts of edema (water retention) in the legs and huge bags under the eyes, hair fell out in clumps, and often eventually proved fatal. At autopsy, these unfortunates also showed advanced and extensive quantities of coronary atherosclerotic plaque.
Low thyroid is usually diagnosed on the basis of the blood test, thyroid stimulating hormone, or TSH. TSH is a pituitary gland hormone responsible for stimulation of thyroid function. When thyroid function flags, the pituitary increases TSH release. Thus, a high TSH signals lower thyroid hormone levels.
The difficulty is in distinguishing normal thyroid function from low thyroid function judged by TSH levels. As the years have passed, in fact, the cut-off for "normal" TSH has drifted lower and lower.
The HUNT Study, I believe, clinches the argument: A TSH of 1.5 or lower, perhaps even 1.0 or lower, is desirable to eliminate the excess cardiovascular risk provided by an underactive thyroid, not to mention feel better: more energetic, clearer thinking, greater well-being.
Having now applied this renewed appreciation for thyroid, I have come to believe that:
--Low thyroid function, even subtle levels, are rampant and far more common than ever previously thought. In my office practice, the case could be made that several people per day are marginally or mildly hypothyroid (low in thyroid). --Restoration of optimal thyroid levels facilitates correction of lipid measures, especially LDL cholesterol and, to a lesser degree, lipoprotein patterns dependent on the insulin axis such as triglycerides and small LDL. It's a lot happier way to correct lipids than statins.
I don't discount the value of feeling better. People who feel better--more energetic, more upbeat, clearer thinking--tend to do better in health overall. If thyroid restoration is a part of that equation, then greater attention should be paid to this facet of health on our way to optimal heart health.
Though I sometimes feel like an endocrinologist dispensing desiccated thyroid (rarely the synthetic T4), I believe that this has been a previously neglected and important part of our effort to achieve coronary plaque stabilization and reversal.