Am I hyperthyroid because my TSH is below normal levels? Should I lower my NDT dose because of that?
One of the most common questions I get from patients is why their TSH is so low on Natural Desiccated Thyroid (NDT). The answer, simply put, is that NDT more closely resembles the natural hormone production of the body than does levothyroxine (LT4). When patients are started on NDT, their bodies often sense that they now have an adequate supply of thyroid hormone and down-regulate the production of TSH. This is why we often see a drop in TSH levels when patients switch to NDT. In some cases, the TSH may drop so low that it becomes undetectable. However, this is generally not cause for concern as long as the patient is feeling well and other thyroid hormone levels are within normal range.
What factors other than thyroid medication dose influence TSH level?
Acording to Raymond Peat, Ph.D there are multiple factors that can influence your TSH levels:
- Aging
- Infection
- Trauma
- Prolonged cortisol excess
- Somatostatin
- Dopamine
- L-dopa
- Adrenaline
- Amphetamin
- Caffeine
- Fever
It is increasingly recognized that, apart from the effect of feedback by the thyroid hormones, various other mechanisms may create a situation in which TSH can appear normal or low, at the same time that there is a real hypothyroidism. In these cases, the diagnosis of thyroid failure may be missed unless specific tests are carried out to assess thyroid function. One such test is the measurement of serum T3 levels. In patients with primary hypothyroidism, serum T3 levels are usually low, even when T4 levels are still within the normal range. A final possibility to consider is the presence of autoimmune thyroiditis. This can lead to impaired thyroid function and again may cause a normal or low TSH despite the presence of hypothyroidism. The diagnosis of autoimmune thyroiditis may be suggested by raised levels of antibodies directed against thyroperoxidase or thyroglobulin in serum.
The takeaway from this post is that if your TSH is low, it’s not just because you’re taking natural desiccated thyroid. You need to look at all of the other factors in your life, too. What changes can you make to help support your thyroid health? Leave a comment and let us know what has worked for you!