Assessing Quality of Life Changes Using Calcitonin in Patients With Hypothyroidism on Biochemical Replacement With Levothyroxine

It is known that a proportion of patients with hypothyroidism despite serum TSH levels being within the normal reference range, may continue to express symptoms of hypothyroidism. Common symptoms include fatigue, muscle pain, weight gain, and mood changes. Saravanan et al. reported in a large community-based survey that patients on levothyroxine even with a normal TSH showed significant impairment in psychological well-being compared with age- and sex-matched controls. These patients are challenging to manage and are often unhappy with they care.

Established treatment of hypothyroidism is levothyroxine. Thyroid follicular cells synthesize and secrete thyroxine and triiodothyronine. However, even when people are receiving adequate levothyroxine replacement therapy, their quality of life may not improve. Calcitonin (CT) is also produced by the thyroid gland, parafollicular cells. Their levels are not tested in hypothyroidism because the exact role of calcitonin in human health and disease is not fully known. CT has long been thought to play an important role in bone and mineral homeostasis, particularly with respect to its ability to regulate calcium metabolism. CT has been found in fish, reptiles, birds, and mammals. Salmon-derived CT is 50-100 times more potent than human CT. Hence, salmon CT (sCT) has been used for medicinal purposes.

There is a need for further research in order to understand the nature of persisting symptoms in patients on T4 monotherapy despite a serum TSH within the reference range. Calcitonin has been shown to alleviate pain in patients with bone or mineral disorders. To date, the use of calcitonin for relief of hypothyroid symptoms has not been studied.