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Low TSH In Hyperthyroidism and Graves’ Disease…And How To Increase It

Published October 1st 2018

Hyperthyroidism is typically characterized by low or depressed TSH levels and elevated thyroid hormone levels (T3 and T4).  When I look at a thyroid panel I’m more concerned with the thyroid hormone levels, but eventually you want to see the TSH normalize as well.  And so I decided to put together an article that discusses the TSH in relationship to hyperthyroidism, how to get it to increase, and how long it usually takes for it to normalize.

First I’d like to explain what thyroid stimulating hormone is.  TSH is a pituitary hormone, and it is released by the pituitary gland to signal the thyroid gland to produce thyroid hormone.  So essentially the pituitary gland monitors the thyroid hormone levels in the body, and if the thyroid hormone levels get too low, then the pituitary gland will produce more TSH, and so you’ll see elevated TSH levels in hypothyroidism.  Of course this article is focusing on hyperthyroidism, and in this case the pituitary gland will produce low amounts of TSH due to the excess of thyroid hormone in the bloodstream.

It’s also worth mentioning that the hypothalamus [1]communicates with the pituitary gland.  In past articles you might have heard me speak about the hypothalamic-pituitary-adrenal (HPA) axis, but there is also a hypothalamic-pituitary-thyroid (HPT) axis.  Chronic stress and other factors can cause dysregulation of both the HPA and HPT axis, and at times this can cause a low or high TSH.

The hypothalamus releases thyroid-releasing hormone (TRH), which is what stimulates the anterior pituitary to secrete TSH.  The TSH stimulates the thyroid follicular cells to release mostly T4 (80%), and some T3 (20%).  Once again, high levels of T4 and T3 have a negative feedback on the anterior pituitary, causing it to secrete less TSH.

How Can You Increase The TSH?

As for how to increase the TSH in those who have hyperthyroidism, the obvious answer is by decreasing the thyroid hormone levels.  Many people with hyperthyroid conditions take antithyroid medication, and if someone is taking a high dose the TSH can increase relatively quickly, and in some cases will become elevated.  When this is the case the medical doctor will lower the dosage of antithyroid medication, and the ultimate goal is to find a dosage that will keep the thyroid hormone levels at healthy levels, and eventually wean the person off of the medication and hope that they will go into remission.  Of course the downside of this approach is that it doesn’t address the cause of the condition.

Antithyroid herbs such as bugleweed can also increase the TSH by decreasing the thyroid hormone levels.  Since bugleweed isn’t as potent as antithyroid medication, it’s not as common to see people take this herb and become hypothyroid, although it does occasionally happen.  Just as is the case with antithyroid medication, bugleweed isn’t doing anything to address the cause of the problem.  L-carnitine [2] when taken in higher doses also has antithyroid activity, and thus can help increase the TSH by decreasing thyroid hormone levels.

How Long Does It Take To Normalize The TSH?

In some cases it can take awhile for the TSH to normalize.  As I mentioned earlier, many times taking antithyroid medication will increase the TSH quickly, especially when higher doses are taken.  However, I also mentioned how the antithyroid medication [3] isn’t addressing the cause of the problem.  So for example, let’s say someone has a TSH of <0.01 μIU/mL, which is common with Graves’ disease, and due to very high thyroid hormone levels they take 20 to 40 mg of methimazole, and after taking the medication the TSH is 3.80.  Although it might appear that the antithyroid medication “normalized” the thyroid hormone levels, it’s probably safe to say that the TSH would become depressed again if the person abruptly stopped taking the antithyroid medication.  It’s also worth mentioning that while a TSH of 3.80 falls within most lab reference ranges, and thus might be labeled as “normal” by many medical doctors, an ideal TSH is between 1.0 and 2.0.

So does this mean that someone with hyperthyroidism can’t normalize their TSH by taking antithyroid medication alone?  Not necessarily, as in the above situation, while the TSH would most likely become depressed again if the person abruptly stopped taking the methimazole, some people do achieve “normalization” of the TSH when taking antithyroid medication for a prolonged period of time.  Of course in the case of Graves’ disease the antithyroid medication isn’t doing anything to address the autoimmune component, which means that over time the person is likely to become hyperthyroid again.   Similarly, if someone has a condition such as toxic multinodular goiter [4], taking antithyroid medication is only a temporary solution.

Let’s get back to the original question, which is “how long does it take to normalize the TSH (without having to rely on antithyroid drugs or herbs)?”   It depends on the person, but this can take anywhere from three to twelve months, and in some cases longer.  Fortunately in most cases it doesn’t take longer than a year for the TSH to normalize when following a natural treatment protocol, but I’ve worked with a few patients over the years where it did take over one year to see the TSH increase and eventually normalize.  And while I can understand people becoming discouraged when the TSH doesn’t increase, initially I would focus more on the thyroid hormone levels.  In other words, as long as the thyroid hormone levels are decreasing I wouldn’t get too concerned about the TSH remaining low.

It’s also important to understand that it’s common for the TSH to not increase at all until both thyroid hormones are well within the laboratory reference range.  So for example, if someone has a TSH that is <0.01, it may not budge until the free T4 is well below 1.5 ng/dL and the free T3 is well below 3.5 pg/mL.  Once again, when someone has hyperthyroidism it is more important for the thyroid hormone levels to be decreasing than for the TSH to increase, and so while the end goal is to have both the TSH and thyroid hormone levels looking good, don’t focus too much on the TSH initially.

Can Taking Iodine Increase TSH Levels?

In this article I’ve mentioned how taking antithyroid medication, bugleweed, and higher doses of L-carnitine can aid in increasing the TSH by lowering thyroid hormone levels.  But how about supplementing with iodine?  Before proceeding I need to let you know that I’m not recommending for anyone reading this to supplement with iodine to increase their TSH levels.  I realize that there are some great success stories from people with hyperthyroidism who took iodine supplements, and while I personally had a very positive experience with iodine supplementation in the past, there are numerous stories of people who didn’t do well when supplementing with iodine.

But high doses of iodine can sometimes help to lower thyroid hormone levels, which will eventually result in normal TSH levels.  For some people this might not make sense, as iodine is a precursor to thyroid hormone, so one may think that taking higher doses of iodine will cause the thyroid hormone levels to further increase, thus exacerbating the hyperthyroid condition.  There is controversy over the mechanisms, as according to the Wolff-Chaikoff effect, large doses of iodine can acutely inhibit thyroid hormone synthesis by inhibiting the enzyme thyroid peroxidase (1) [5].  However, some argue that the decrease in thyroid hormone when consuming iodine isn’t due to the Wolff-Chaikoff effect, but is instead due to an interference in organic binding of iodine by the thyroid gland, which results in an abrupt decrease in the rate of T4 release (2) [6].

Lithium can also lower thyroid hormone levels, and thus cause the TSH to increase.  I don’t commonly recommend lithium to my patients, and I discussed why in an article I wrote entitled “Can Lithium Help With Hyperthyroidism and Graves’ Disease? [7]”.  That being said, there are some natural healthcare professionals who do recommend lithium to their hyperthyroid patients, and some recommend both lithium and iodine.

What’s The Deal With Subclinical Hyperthyroidism?

Most people with Graves’ disease will not only have an undetectable TSH, but will have elevated thyroid hormone levels.  This also is usually the case with toxic multinodular goiter.  But some people have subclinical hyperthyroidism, which is when the TSH is low or depressed but the thyroid hormone levels are normal.  Some people with subclinical hyperthyroidism will develop overt hyperthyroidism, especially when the TSH levels are less than 0.1.

In summary, the TSH is commonly depressed in hyperthyroidism and Graves’ disease.  Although antithyroid medications and herbs such as methimazole and bugleweed can cause an increase in the TSH, these agents aren’t doing anything for the cause of the problem.  As for how long it takes for the TSH to normalize without the help of antithyroid medication or bugleweed, it can take up to 12 months, and in some cases longer than this.  But as long as the thyroid hormone levels are consistently decreasing there shouldn’t be a concern.