The pituitary gland releases the thyroid-stimulating hormone (TSH), which is responsible for stimulating the release of the thyroid hormones namely thyroxine (T4) and triiodothyronine (T3). These two thyroid hormones are necessary for various body functions.
It is vital that person must keep their TSH levels within the normal range because it can affect the production of thyroid hormones. However, various factors can result in a low TSH leading to several health problems. For this reason, it is valuable to understand the possible reasons for this hormone imbalance along with its symptoms and treatment options.
TSH Levels
The normal values will vary depending on your age. Pregnant women also have a different set of values, which is presented in the table below.
| Normal Levels | |
| Premature Birth (28 to 36 weeks) | 0.7 to 2.7 mIU/L |
| Children: | |
| Birth to 4 days | 1 to 3.9 mIU/L |
| 2 to 20 weeks | 1.7 to 9.1 mIU/L |
| 21 weeks to 20 years old | 0.7 to 6.4 mIU/L |
| Adults: | |
| 21 to 54 years old | 0.4 to 4.2 mIU/L |
| 55 to 87 years old | 0.5 to 8.9 mIU/L |
| During Pregnancy: | |
| First Trimester | 0.3 to 4.5 mIU/L |
| Second Trimester | 0.3 to 4.6 mIU/L |
| Third Trimester | 0.8 to 5.2 mIU/L |
Low and High TSH Levels
Because the normal values differ depending on your age, the high and low result will also vary depending on which category you belong. In general, when the TSH level is above the normal range, your TSH level is high. If it is below the normal range, the TSH level is low.
For example, an average adult has a normal TSH level ranging from 0.4 – 4.2 mIU/L. If the result is more than 4.2 mIU/L, the TSH level is high. A low TSH result will have a TSH level that is below 0.4 mIU/L.
What does Low TSH Mean and What are the Causes?
Keep in mind that the pituitary gland plays a role in the production of eight hormones, including the TSH and thyroid hormones (T3 and T4).
When a patient has low levels of TSH, it indicates that a patient has a health problem. The common causes are:
- Hyperthyroidism
Hyperthyroidism is a medical condition wherein a patient will have high levels of thyroid hormones and a low TSH level.
When a patient has hyperthyroidism or Grave’s diseases, he will have an overactive thyroid wherein there is an increase in the levels of thyroid hormones. Because TSH is responsible for triggering the release of these thyroid hormones, the body’s natural response is to lower the TSH levels.
- Problem with the Pituitary Gland
In cases of Hashimoto thyroiditis or hypothyroidism, the patient’s thyroid hormones are low, thus, there should be an increase in TSH levels.
When both the thyroid hormones and TSH levels are low, it indicates that the patient’s pituitary gland is either weak or damaged because of a disease, head injury, or tumor.
It is crucial to seek medical attention if you have hypothyroidism and low TSH levels. Your doctor will order additional blood tests or brain scans to detect the underlying cause of the problem.
What are Symptoms:
The most common cause of low TSH level is a hyperactive thyroid gland. Because the thyroid hormones help regulate various body functions such as metabolism, an increase in these hormones can lead to the following symptoms:
- General Symptoms
A patient will experience restlessness, nervousness, muscle cramps, involuntary muscle movements, weakness, and fatigue. In addition, most people with thyroid problems have heat intolerance, wherein a warm weather is unbearable for them. They will sweat more during these days.
- Lung and Heart Problems
It can also lead to several heart problems such as an increase in blood pressure and irregular heartbeats. In some cases, this abnormality can also affect the heart muscle leading to cardiomyopathy. In a worst-case scenario, heart failure may also occur.
A person with low TSH may also experience shortness of breath even when doing normal activities.
- Digestive System
Weight loss is evident in people with this condition even though they have an increase in appetite, because they have an accelerated metabolism. However, compared to younger people, the elderly may experience a loss of appetite.
Bowel movements may also be affected. One may feel the need to defecate more often than usual. However, vomiting and abdominal pain will rarely occur.
Some patients may also develop a goiter, or an enlargement of the thyroid gland, which may affect their ability to swallow food.
- Skin and Hair
When your TSH is low, there will be an increase in blood flow, which results in a warm and reddish skin. One may also experience itchiness and hives. Furthermore, the skin of the leg, specifically the shin, may appear like the peel of a dried orange with a darker hue. Some patients also experienced hair loss when their TSH level is low.
- Personality and Mental Problems
Personality changes may occur in these people. They may experience depression, irritability, anxiety, insomnia, hallucinations, and delusions. This abnormality may also cause a decline in mental skills such as an inability to concentrate, memory problems, and confusion.
What You Should Do When the Levels Are Low?
When your TSH levels are low, it is vital to consult your doctor to find the underlying cause of the abnormality. For there, your doctor will prescribe the appropriate medication and other recommendations, which includes the following:
- Medications
Doctors will typically prescribe an anti-thyroid drug to increase your levels caused by hyperthyroidism. Depending on the severity of your condition, surgery may be necessary. This type of surgical procedure has a high chance of success for complete recovery.
For patients with hypothyroidism, your doctor may prescribe hormone replacement therapy to boost your TSH level.
- Diet Changes
A dietary change is essential to increase your TSH. The most valuable minerals for hyperthyroidism are selenium and iodine. You have to include foods that are rich in these two minerals. The common sources of iodine are sea vegetables, cranberries, and yogurt. For examples of selenium-rich foods, you can eat beef liver, chicken, halibut, and Brazil nuts.
In addition, a low TSH can also be a result of abnormal blood sugar levels. Your doctor will prescribe a medication to balance this abnormality. You also have to follow a diet plan that will help regulate your blood sugar levels.
- Supplements
If a change in diet is not enough, you doctor may recommend taking iodine supplements. Taking progesterone and selenium can also help in the conversion of the thyroid hormone T4 to T3. However, if the doctor already prescribed thyroid hormones, iodine supplements are unnecessary.
- Exercise
One way to stimulate your pituitary gland and boost the levels of TSH is through daily exercises such as yoga, breathing exercises, and meditation. On the plus side, doing regular exercises can help balance your hormones and improve your overall health condition.
