What is thyroid hormone?
Thyroid hormone is a bodily chemical produced by the Thyroid gland, a butterfly-shaped endocrine gland that is located in the lower front of the neck. Thyroid hormone reaches every tissue in the body after being released into the bloodstream. These hormones play crucial roles in all vital body activities such as controlling how our body uses energy, maintaining body temperature and heart rate, etc. Thyroid hormones help with things like growth, mood, and metabolism.
What is a TSH test?
A TSH test means measuring the level of thyroid-stimulating hormone (TSH) in our blood. TSH is made by the brain to command the thyroid gland how much thyroid hormone to produce. A TSH test is done to detect if your thyroid is overactive (hyperthyroidism) or underactive (hypothyroidism).
What is a T4 test?
A T4 test or thyroxine test in the thyroid measures the amount of thyroxine (T4) in the blood. T4 is a name of hormone that is produced from the thyroid gland. T4 typically controls metabolism, energy levels, and body functions. The test helps to diagnose thyroid problems like hypothyroidism or hyperthyroidism. The value of normal total T4 in adults ranges between 5 to 12 micrograms per deciliter (mcg/dl) of blood. Normal free T4 levels range from 0.8 – 1.8 nanograms per deciliter (ng/dl) of blood, though it varies by age and pregnancy status.
What is a T3 test?
A T3 test or triiodothyronine test is a measurement of triiodothyronine (T3) in blood. It is also diagnosed to detect thyroid conditions. T3 is a thyroid gland hormone that is responsible for many bodily functions, including growth, heartbeat, and body temperature. The T3 test measures the amount of both free and bound T3 in blood. T3 test is given for both – hyperthyroidism and hypothyroidism.
How TSH Levels Change
TSH levels are the main concern for thyroid-related problems. A high TSH indicates an underactive thyroid gland. An overactive thyroid is indicated by low TSH. Both situations are concerning.
TSH is not the same as thyroid hormones. The thyroid hormones are triiodothyronine (T3) and thyroxine (T4). Thyroid hormones are crucial to regulate several processes including heart rate, body temperature, caloric expenditure, and many more.
When thyroid hormone levels are low, the pituitary gland produces more TSH, which instructs the thyroid to produce more. When TSH levels are high, the pituitary tells the thyroid to slow down by releasing less TSH. As a result, high TSH and low TSH situations can occur.
Interpreting Results
You will better understand the importance of a low or high TSH level for the thyroid if you know when and why thyroid hormones are released. Not releasing enough TSH is also a concern.
TSH is measured with a blood test and its unit is mU/L. This acronym stands for milliliters per liter, one milliliter is equivalent to one-thousandth of a unit.
TSH typically ranges between 0.4 and 4.5 mU/L in normal adults. But it can be effective with other factors like age, sex, bodily status, etc.
What is a normal thyroid (hormone) level?
The value of the normal thyroid level depends on an individual’s age, sex, and other health status. For example, if a woman is pregnant, her thyroid result may vary. There is also a difference in TSH levels between males and females.
Healthcare professionals generally consider the range between 0.4 to 4.0 mU/L to be normal for thyroid.
Here we present a table below displaying the estimated TSH levels:
| Hyperthyroidism | 0 to 0.4 mU/L |
| Normal | 0.4 to 4 mU/L |
| Mild hypothyroidism | 4–10 mU/L |
| Hypothyroidism | 10 mU/L |
By sex
Women experience thyroid dysfunction at a higher rate than men do. 1 in every 8 women is more likely to have thyroid problems but age and other variables play a role. And during the pregnancy period and around menopause, thyroid problems can arise even more. This includes both hypothyroidism and hyperthyroidism.
Thyroid disorders are linked to sexual dysfunction too. It may affect men more than it does women. 59 to 63% of male hypothyroidism patients have sexual dysfunction in comparison to 22 to 46% of female hypothyroidism patients.
- Normal TSH levels in men should be 0.4–4.0 mIU/L (Free T4: 0.8–1.8 ng/dL, Free T3: 2.3–4.2 pg/mL)
- Normal TSH levels in women should be 0.4–4.0 mIU/L (Free T4: 0.8–1.8 ng/dL, Free T3: 2.3–4.2 pg/mL)
By age
Thyroid hormone levels in the blood usually rise with age. According to various research, hypothyroidism is the most prevalent thyroid condition in adults over 60. Its prevalence increases steadily with age. Around 7 to 14% of elderly people may have higher TSH levels as they grow older.
| Age Group | TSH Range (mIU/L) |
| Children (1–12 years) | 0.7–6.4 mIU/L |
| Adolescents (13–19 years) | 0.5–4.3 mIU/L |
| Adults (20–60 years) | 0.4–4.0 mIU/L |
| Older adults (60+ years) | 0.5–8.9 mIU/L |
In pregnancy
Certain thyroid hormones naturally increase in the blood during pregnancy time. This is essential for the development of the fetal brain and nervous system. At the same time, blood TSH levels fall. During pregnancy, the TSH level in the blood ranges between 0.4 and 0.5 mU/L.
Despite gradually increasing during the second and third trimesters, TSH levels in non-pregnant women remain below normal. Excessively high or low TSH levels during pregnancy impose some risk of miscarriage and other pregnancy-related problems like premature birth, lower birth weight, preeclampsia, etc. The doctor carefully supervises the TSH condition during this pregnancy journey.
In children
Thyroid hormone levels peak at birth and decrease as a child grows older. TSH levels in children can therefore vary with different ages of childhood. Here we present a table showing TSH levels for children of different ages:
| Age | Reference ranges (mU/L) |
| Time of birth | 3.84 to 11.75 |
| 1 month | 1.18 to 3.57 |
| 1 year | 1.17 to 3.55 |
| 5 year | 1.15 to 3.47 |
| 12 year | 1.09 to 3.31 |
| 18 year | 1.05 to 3.16 |
Causes of High TSH
Thyroid disease occurs unknowingly. High thyroid-stimulating hormone (TSH) levels are an indication of an underactive thyroid condition. It is called hypothyroidism, the most common form of thyroid. This can come due to:
- Thyroid gland produces insufficient thyroid hormones (T3 and T4).
- The pituitary gland compensates by increasing TSH production to stimulate the thyroid.
- Hashimoto’s thyroiditis (an autoimmune disorder).
- Iodine deficiency or excess.
- Thyroid surgery or radiation therapy.
Causes of Low TSH
Low TSH can be seen due to:
- Autoimmune diseases (e.g., Graves’ disease).
- Toxic nodules or lumps in the thyroid gland.
- An abnormally enlarged thyroid gland (goiter).
- During normal pregnancy due to elevated levels of human chorionic gonadotropin (hCG).
- Pituitary gland dysfunction leads to insufficient TSH production.
Treating high levels of TSH
High levels of TSH are a sign of hypothyroidism. It is generally treated with levothyroxine, which is a medication that replenishes lost thyroid hormones. Levothyroxine is taken once daily on an empty stomach, preferably 30 minutes before meals.
Regular blood tests are a must to monitor the effectiveness of a treatment. Levothyroxine works with other foods, including dietary fiber, soybean flour, cottonseed meal, and walnuts. So, these foods should be avoided. For the best possible medication efficacy, it is also advised to avoid some beverages that can interfere with absorption. This can be some citrus juices like grape juice.
Some home remedies can be helpful here. Thyroid can be managed with a controlled diet and lifestyle. People can take advantage of yoga in managing TSH. Also, foods like pumpkin seeds, almonds, and flax seeds are good sources of omega-3 fatty acids, magnesium, and heart-healthy fats.
Treating low levels of TSH
Low levels of TSH is an indication of hyperthyroidism. It is treated by reducing the thyroid levels. Beta-blockers and antithyroid drugs are commonly used to treat symptoms of hyperthyroidism.
Another option is radioiodine therapy, which uses radioactive iodine to destroy hormone-producing cells. Though there remain the risks of hypothyroidism.
In the most severe cases, surgery is the ultimate to remove the thyroid gland. It is advised when no other treatment works. In addition to professional care, home remedies like drinking soothing teas like ashwagandha or chamomile can help to manage symptoms.
