Let's Review the Thyroid

I've talked about hypothyroidism in the past, but I thought now would be a good time to review this again. It seems I've had an inordinate number of patients lately who have hypothyroidism. Some I've found through their HTCA lab work when working them up for bio-identical hormone pellet replacement therapy. Some I've picked up on when they come in for weight loss consults, and others have sought me out specifically to evaluate their thyroid.

I had an internal medicine practice for 20 years and thought I was doing a great job managing hypothyroidism (underactive thyroid). Afterall, I have hypothyroidisim myself. I was always taught that TSH and T4 were all the labs you needed to screen for hypothyroidism. If they were normal and the patients didn't feel well then they were probably depressed or just needed to follow a better diet and exercise regimen. Since becoming a Diplomate of the American Academy of Anti-Aging Medicine, I now know TSH (the pituitary hormone) is not the most sensitive test. A patient's free T3 (active thyroid hormone) is the best clue as to whether or not he/she has hypothyroidism. And most importantly we want hormone levels to be "optimal" not just in the "normal" range. 

There are multiple causes of hypothyroidism, but for the purposes of this blog, let's focus on the ones I see most commonly which are primary hypothyroidism (thyroid failure) and conversion failure of T4 (inactive pro-hormone) to T3 (active hormone). Primary hypothyroidism is pretty straight forward. The thyroid basically poops out. This can be do to an autoimmune process like Hashimoto's thyroiditis, radiation treatments, or just general aging. A number of different factors can impair conversion of T4 to T3 and these include:

  • Physiological factors: old age or significant calorie restriction with dieting
  • Certain medications:  Amiodarone, steroids, beta blockers and synthetic progestins (by the way.... I HATE synthetic hormones)
  • Pathological factors: kidney or liver disease, malnutrition, increased cortisol, postop
  • Vitamin deficiencies: Zinc, Selenium and Iodine are essential to normal thyroid function.

Hypothyroidism can also be caused by failure of thyroid receptors on organs in the body to actually take up thyroid hormone. This is often seen in adrenal fatigue and that is a whole other topic for a new blog!

In the 1920's it's estimated that about 10% of the population was hypothyroid. By 1940 that doubled to 20% and increased again in 1976 to approximately 30%. Dr. Jacques Hertoghe, a pioneer in thyroid endocrinology has estimated that by 1990 about 80% of the population had some degree of hypothyroidism. Because of all the genetically modified foods, chemicals, stress, medications and synthetic hormones we are exposed to these days, that estimate is probably pretty accurate.

Symptoms of hypothyroidism are depicted in the photos above. So how do we diagnose hypothyroidism? A good history and physical exam of the patient is always the place to start. After that, some or all of the following labs are indicated.....TSH, T4, free T3, rT3, and TPO antibodies. This is a good place for clinicians to start. Again, we want "optimal" levels, not just "normal". How a patient feels should be the main driver of treatment. Of course we use lab to make sure we do not make someone artificially HYPERthyroid which can have adverse effects on the body, too.

There are multiple medications used to treat hypothyroidism. Most well known is probably Synthroid (or its generic levothyroxine). Synthroid is predominantly T4. I personally prefer Naturethroid, WPThyroid or Armour Thyroid. I take NatureThroid myself. It comes in 13 different doses, is hypoallergenic and is a combination of T3 and T4. I like to have T3 on board first thing in the morning and then the T4 that remains can convert to active T3 through the rest of the day. WPThyroid is for patients with gluten sensitivities. All three are made from dessicated pork thyroid. Regardless of which preparation of thyroid medication you take, I highly recommend brand name only. Since generics can vary by 20% from brand name, that could be a big swing month to month in your metabolism and how you feel. It's beyond the scope of this particular blog, but thyroid hormones can also be compounded with any strength and percentage of T4 and T3 a doctor wants to prescribe. 

And just as a side note....your fur babies can become hypothyroid, too. So if they are fat and lethargic and you haven't been feeding them junk, you might want to ask your vet to check their thyroid. But it's not just about being overweight or fatigued. Optimal thyroid function improves many aspects of our body, not just the ones we can see and feel. It helps lower cholesterol, improves congestive heart failure by helping the heart pump better, decreases inflammatory markers like C-reactive protein and homocysteine, and helps protect the bones from osteoporosis.

This is just a very brief overview of hypothyroidism. Many, many textbooks are devoted entirely to the thyroid and its diseases and metabolism. There are so many other things we could cover, but we'll save those for another day! At Sei Bella we wish you all the best Health|Wellness|Beauty!

Anne R Trussell MD