Is My Immune System Attacking My Thyroid? Understanding Hashimoto’s Thyroiditis
Hashimoto’s Disease (autoimmune thyroiditis) is the most common cause of hypothyroidism, occurring in 4-10% of the US population. In this condition, the body’s immune system attacks the thyroid gland, causing it to become chronically inflamed, leading to malfunction. It is also the most common autoimmune disorder in adults. Those affected have an increased risk of developing other autoimmune disorders, as well.
Most people with Hashimoto’s disease have “subclinical hypothyroidism”, meaning that the diagnosis has not been recognized. In these people, blood tests reveal thyroid abnormalities (elevated TSH with normal T4 and T3) and can identify the presence of thyroid antibodies, but they are either asymptomatic or the symptoms have not been associated with possible hypothyroidism.
In addition, many people with normal thyroid function tests have detectable antithyroid antibodies, meaning they have thyroid inflammation and Hashimoto’s disease, but do not yet have detectable thyroid hormone functional problems. These individuals are at risk of developing hypothyroidism over time.
In Hashimoto’s disease, T and B lymphocytes, cellular mediators of our immune system, attack the thyroid gland and accumulate within. This is generally an asymptomatic phenomenon, but sometimes the gland swells, and a goiter develops. On occasion, the gland can even be somewhat painful, though in most cases, the thyroid inflammation is unrecognized. Antibodies against protein components of the thyroid gland (thyroglobulin, thyroid peroxidase) can be detected in the blood.
So, how do I know if I am affected?
First, let’s talk about clinical hypothyroidism. Thyroid hormone is an essential regulator of cellular metabolism, so when levels are low, there are consequences. In this circumstance, people will experience a number of symptoms, including fatigue, weight gain, dry skin and thinning hair, constipation, cold intolerance, difficulty concentrating, aches and pains, and even heart problems and anemia. Since many of these symptoms are nonspecific and may occur in many different situations, one must suspect possible thyroid disease and proceed with testing. As noted above, the physical examination of the thyroid gland is usually normal, but there are several other subtle physical signs that a physician can detect to increase suspicion.
Thyroid function blood testing is diagnostic: the TSH (thyroid-stimulating hormone) will be elevated and the circulating thyroid hormones T4 and/or T3 will be depressed. TSH is produced by the pituitary gland and regulates thyroid hormone production. When T4 or T3 levels are low, the pituitary produces more TSH in order to stimulate the thyroid to produce more hormone.
In subclinical hypothyroidism, the TSH rises, but the thyroid gland is able to respond by producing more T4 and T3. In this circumstance, the TSH is elevated, yet the T4 and T3 are normal.
In order to establish a diagnosis of Hashimoto’s disease, one detects antithyroid antibodies in the blood; either TPO (thyroid peroxidase), thyroglobulin or both. Once again, these antibodies can be detected years before even subclinical hypothyroidism occurs, that is, long before the TSH begins to rise.
What Causes Hashimoto’s Thyroiditis?
No one knows for certain, but like other autoimmune diseases, there are a number of hypotheses. For one, we know that there is a hereditary component. Although no single gene is responsible, several genes have been associated with an increased risk. Hashimoto’s disease often runs in families and identical twins have about a 30% concordance rate, which means that while the genetic component is substantial, environmental factors play a large role. Smoking and childhood obesity are known risk factors. It is possible that viral or bacterial infections may initiate the autoimmune process, but this has not been demonstrated with certainty. The leaky gut hypothesis is a leading factor in developing autoimmunity and Hashimoto’s disease in particular. Dietary modification, repairing gut dysbiosis and inflammation can be helpful. Gluten intake has been associated with the development of thyroid peroxidase antibodies, even in the absence of Celiac disease. While it is always important to “heal the gut”, it is very difficult to turn off Hashimoto’s disease; while antibody levels can be reduced, thyroid autoantibodies usually remain.
How is Hashimoto’s Disease Treated?
There are 2 parts to this question: can one treat the underlying autoimmune process in order to shut down the condition, and how does one manage low thyroid hormone levels?
Right now, we do not have effective tools to turn off the thyroid gland autoimmune reaction, so the major treatment approach is normalizing thyroid hormone levels. It is still important to stop smoking, follow an anti-inflammatory diet and address any gut dysbiosis and inflammation. But the most effective treatment is the supplementation with thyroid hormone to normalize and restore metabolic balance.
In patients with clinical hypothyroidism, the decision to initiate treatment is straightforward. Controversy arises in cases of subclinical hypothyroidism or in patients with known antithyroid antibodies who have slowly rising TSH. In fact, there are a number of controversies with respect to the best treatment and monitoring programs for hypothyroidism, a discussion that I will take up in a future blog post. These include whether to treat with levothyroxine ( T4) alone or in combination with T3 ( such as in desiccated thyroid hormone products, like Armour thyroid or Nature-Throid), at what TSH level should one initiate treatment, what are the ideal TSH, T4 and T3 levels, and how best to monitor treatment.
For those patients with Hashimoto antibodies and normal or trending low thyroid function, we often use herbal and nutritional supplements to enhance natural thyroid function. For example, persons with selenium and zinc deficiency can develop hypothyroidism. B Vitamins are essential for proper thyroid function and Vitamin D deficiency has also been associated with low thyroid. Since thyroid hormone is produced from tyrosine, an amino acid, and iodine, supplementation with these nutrients may help as well.