Relationship Between Hashimoto's Thyroiditis and Osteoporosis

Hashimoto’s thyroiditis, also referred to as chronic lymphocytic thyroiditis, is a condition that results from the immune system’s attacks on the thyroid gland. As an autoimmune disease, the body’s immune system views the gland as a harmfully invasive object, or something that is foreign, which compels its protective mechanisms to attack the thyroid gland and cause inflammation. This renders the gland damaged, which translates to having low capacities of producing the necessary hormones - triiodothyronine (T3), thyroxine (T4), and calcitonin - that coordinate various body activities. Given calcitonin’s role in regulating bone resorption and breakage, the absence of calcitonin leads to one of the many complications caused by Hashimoto’s thyroiditis — osteoporosis.

Causes

The thyroid gland is a part of the body’s endocrine system, and contributes in coordinating several activities and functions of the body through the production of two integral hormones — thyroxine and triiodothyronine. These regulate the body’s usage of carbohydrates and fats, temperature, and protein production. These hormones also affect the person’s heart rate.

The body’s immune system naturally guards it from perceived invasive bacteria, viruses, and other foreign substances by creating antibodies and lymphocytes to help “fight off” invaders. Such protective mechanisms, and the “war” that ensues, cause inflammation of the affected tissue. When this happens to the thyroid gland, damage is caused and enables hypothyroidism to ensue.

Some evidence shows that Hashimoto’s thyroiditis may be associated with other autoimmune diseases such as celiac disease and Type 1 diabetes. Various factors including the person’s gender, age, and heredity may strengthen his vulnerability towards acquiring the said condition. However, the reason why the immune system advances attacks on thyroid glands remains unknown.

The Role of Calcitonin

Apart from producing thyroxine and triiodothyronine, the thyroid gland also produces calcitonin. Calcitonin inhibits the activity of osteoclasts; aids the regulation of calcium levels found in the blood; and hinders unhealthy frequency of bone resorption or removal. As such, calcitonin significantly aids in bone-building activities through slowing down the body’s rate of breaking down bones. The significant roles of calcitonin establish a crucial link between Hashimoto’s thyroiditis and osteoporosis.

Linking Hashimoto’s thyroiditis and Osteoporosis: The Lack of Calcitonin

Osteoporosis is a bone disease wherein bone mass is low and deterioration of bone tissue is prominent. These lead to the fragile condition of the bone, and render the person to become more prone to incurring fractures.

Due to inflammation of the thyroid gland, its production of hormones T3, T4 and calcitonin is reduced or impaired. As a result, the body’s activity of breaking down bones significantly increases due to the lack or absence of calcitonin. Bone resorption becomes largely unrestrained, and thus leads to the occurrence of osteoporosis, given that the rate of bone resorption is too quick compared to replacement or formation activity.

References

https://www.medicinenet.com/hashimotos_thyroiditis/article.htm

https://www.mayoclinic.com/health/hashimotos-disease/DS00567

https://www.vivo.colostate.edu/hbooks/pathphys/endocrine/thyroid/calcitonin.html