The thyroid is a small but one of the most important endocrine glands of the body. It secretes two hormones very crucial for controlling metabolic rate, thyroxine (T4) and triiodothyronine (T3). These hormones increase the oxygen consumption and stimulate the synthesis of new proteins in the cells. The activity of this crucial gland is regulated by another hormone called thyroid-stimulating hormone (TSH). TSH is not produced in the thyroid but produced by the pituitary gland located in the brain. Thus, abnormal TSH levels may hinder the normal functioning of this gland.

Symptoms: The symptoms are not specific and can be easily misdiagnosed with other common disorders. Some of the common symptoms of abnormal TSH levels (or abnormal thyroid function) are fatigue, weakness, nervousness, weight gain or weight loss, tremors, sudden paralysis, issues with vision such as light sensitivity, muscle weakness, and insomnia.

Control of thyroid: TSH, secreted by the pituitary, causes secretion of the thyroid. Higher levels of thyroid hormones “switch off” the section of TSH. However, in certain conditions the activity of the thyroid is compromised making it either overactive (hyperthyroidism) or underactive (hypothyroidism). Thyroid disorders are more common in females as compared to males.

Reference range and interpretation of TSH levels: The reference range of TSH is still a debatable issue but a commonly accepted range in 0.4 mU/L to 2.5 mU/L.

A high level of TSH indicates lower activity of thyroid gland (underactive). Thus, excess TSH is secreted to provide a signal to the thyroid gland to produce hormones.

A low level of TSH indicates overactive thyroid that consequently increases the thyroid hormones in the blood. These higher levels of hormones inhibit the secretion of TSH from the pituitary gland.

Treatment: Since the thyroid gland is central to energy metabolism, any disorder of this gland requires a careful examination and treatment by an expert, preferably an endocrinologist. However, certain medications that decrease thyroid hormone levels and other treatments, which increase the levels of thyroid hormones are prescribed to control abnormal TSH levels. However, a blood test is performed to detect abnormal TSH levels and accordingly a treatment is advised.

TSH levels in the body control the proper functioning of thyroid gland. An underactive or overactive thyroid gland causes widespread disruption of body functions due to its critical role in body maintenance and energy homeostasis.