Low TSH Levels – What does it Mean?

TSH is a hormone secreted by the pituitary gland. This hormone is secreted to stimulate the release of thyroid hormones from the thyroid gland. TSH levels are raised in the case of hypothyroidism. Hypothyroidism is characterized by low levels of the thyroid hormones, which in turn results in various clinical symptoms like weight gain, fatigue and lethargy.

Low TSH levels can be due to various reasons. Such reasons include subclinical hyperthyroidism, excessive levothyroxine supplements or even non-thyroidal illness. If a person is not on levothyroxine therapy, then triiodothyronine and thyroxine levels should be considered. If these levels are normal, then some non-thyroidal illness can be suspected.

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low tsh level diagram thyroid


Hyperthyroidism is the condition where thyroid hormones are secreted at an increased rate. Increased amounts of these hormones can result in elevated heart rate and blood pressure. It can also be accompanied by tremors.


This condition can be caused due to a variety of reasons. The most common reason is Grave’s disease, which is an autoimmune disorder, characterized by over secretion of thyroid hormones. Other reasons can include excess iodine intake, thyroiditis and tumors of the thyroid gland.


The common symptoms of this condition include increased metabolic rate. This increased metabolic arte results in various abnormalities like elevated blood pressure, increased heart rate and tremors. The tolerance of heat can also be reduced. It can also cause greater bowel movement, excessive weight loss and can also result in irregular menstrual cycles in some women. Some other symptoms include hair loss, increased appetite, restlessness, nausea, vomiting and development of breasts in males. The serious complications can range from strokes to congestive heart failure.


The diagnosis of this condition is done by performing various tests


Various treatment options can be used which include radioactive iodine therapy, surgery and some medications.

The antithyroid medications can be given to reduce the secretion of thyroid hormones. An example of this medication includes methimazole.

The surgical method includes removal of a section of thyroid gland or whole of the thyroid gland. In such cases, thyroid supplements should be taken by the patient to prevent hypothyroidism.

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Radioactive iodine therapy is used in some cases. The radioactive iodine damages and kills the cells which produce thyroid hormone. But this therapy also has a very major side effect that it reduces the white blood cells count. So this is avoided in majority of the cases.

Excessive Levothyroxine Supplement

Levothyroxine is prescribed to persons suffering from hypothyroidism. In some cases, these doses may be excess in quantity. The presence of excess of hormone in the blood stimulates the pituitary to secrete less of the hormone TSH. Excess of this hormone has many other side effects. Some of them are stated below.

Too much of levothyroxine in circulation can cause the skin temperature to rise abnormally. Excessive hormone causes an abnormal increase in metabolism, leading to excessive production of heat in the body. Continuous high doses can result in long term rise in temperature, known as malignant hyperthermia.

In the gastrointestinal system, it increases the speed of bowel movement. This results in sudden loss of weight of the patient, despite of the increased appetite. This is due to the diarrhea,that the food is not absorbed properly and moves out through the system.

Excess of this hormone can also lead to persistent nervousness and irritability. The affected individual can also experience reduced concentration and difficulty in memory and confusions. In very severe cases, coma can also occur.

Non-thyroidal Illness

This kind of disease is characterized by abnormal levels of thyroid hormones without any defined abnormality in the gland function. Such changes can be seen in a variety of conditions which includes renal disease, pulmonary disease, cardiovascular disease, sepsis, trauma, myocardial infarction and a few more such conditions. Such illness does not show any clinical presentation in the patient physically. This is a physiological process in which the hormone levels in the blood are quite low, but this condition should not be given a try for alteration using medications or any other treatment. The patient generally recovers from the lower levels by themselves.

Any medical therapy should only be given if the serum thyroid levels drop down below 4 microgram per deciliter. This is the danger low level of thyroid hormones. The lower level of the hormone is also accompanied by reduced action of the hormone. In some cases, the levels of the hormone can even be raised. This situation is seen in patients who are recovering from the condition. However, if the condition persists for a long period of time, thyroid hormone supplements are necessary otherwise it can result in life threatening condition. Triiodothyronine injections should be given to such patients. An alternate therapy can also be given where TRH hormone is administered. This hormone stimulates the release of TSH which further stimulates the release of thyroid hormones from the thyroid gland

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