The thyroid is a small organ located in the neck that makes and releases certain hormones. The main function of these hormones is controlling the metabolism, or how our bodies use energy. These hormones include Triiodothyronine (T3) and Thyroxine (T4). In addition to metabolism, T3 and T4 regulate body temperature, muscle and digestive function, and the growth of hair and nails.
The production of T3 and T4 is regulated by thyroid stimulating hormone (TSH). TSH is produced by the pituitary gland, a pea-sized gland located in the brain. TSH binds to cells in the thyroid, stimulating them to make the right amount of T3 and T4. Once these hormones reach a certain level, they prevent the release of TSH. When these hormones drop below a certain level, the hypothalamus in the brain releases hormones that stimulate the pituitary gland to release TSH. This negative feedback loop keeps the thyroid hormones in balance and your body functioning normally.
What is Hypothyroidism?
An underactive thyroid gland is known as hypothyroidism and is when the thyroid does not produce enough thyroid hormones. This can occur if the pituitary gland does not produce enough TSH, or if the thyroid is injured and does not make enough T3 or T4.
Symptoms of hypothyroidism
The thyroid influences the function of multiple body systems, including the metabolism, digestive system, the heart, the brain, and the bones. This means that hypothyroidism can cause a range of symptoms in different parts of the body. Symptoms of hypothyroidism include:
- Weight gain
- Muscle cramps
- Irregular periods
- Dry and pale skin
- Sensitivity to cold
- Thin hair + hair loss
- Chronic constipation
- Lowered sex drive
Causes of hypothyroidism
According to the NHS, hypothyroidism can be caused by various health conditions, such as:
- Autoimmune disorders such as Hashimoto’s thyroiditis, in which the immune system attacks the thyroid
- Thyroid surgery
- Certain medications
- Radiation therapy in the head and/or neck area
- Iodine deficiency
- Disorders of the pituitary gland
- Congenital disorders
Treatment of hypothyroidism
Hypothyroidism is usually treated by hormone replacement therapy, or taking medication that replaces the hormone your thyroid does not make enough of. The medication that is most commonly used is called levothyroxine. With daily medication use, people with hypothyroidism can live normal and healthy lives. While hypothyroidism is a lifelong condition, it can be managed with medication and regular follow-up appointments with your doctor.
What are normal thyroid values?
Normal thyroid values depend on a number of factors, such as gender and age. As you age, your TSH levels will change. For example, babies have a much higher TSH value in their first week of life than someone aged 30. If you’d like to learn more about the normal range for T3, T4, and TSH, read our blog.
Are you curious about your thyroid hormones? With Homed-IQ’s Thyroid Test you can easily measure your T3, T4 and TSH levels from home. This test only requires a few drops of blood from a finger prick.
NHS (2023) Underactive thyroid (hypothyroidism) symptoms Retrieved on January 12, 2023, from https://www.nhs.uk/conditions/underactive-thyroid-hypothyroidism/symptoms/
NHS (2023) Underactive thyroid (hypothyroidism) causes. Retrieved 12 January 2023 from https://www.nhs.uk/conditions/underactive-thyroid-hypothyroidism/causes/
NHS (2023) Underactive thyroid (hypothyroidism) treatment Retrieved January 12, 2023, from https://www.nhs.uk/conditions/underactive-thyroid-hypothyroidism/treatment/
Mulder JE. Thyroid disease in women. Med Clin North Am. 1998 Jan;82(1):103-25. doi: 10.1016/s0025-7125(05)70596-4. PMID: 9457153.
Gesing A. The thyroid gland and the process of aging. Thyroid Res. 2015 Jun 22;8(Suppl 1):A8. doi: 10.1186/1756-6614-8-S1-A8. PMCID: PMC4480281.
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