Thyroid stimulating hormone is lowered - what does it mean?
The content of the article:
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The hormone TSH is lowered: what does it mean
Additional analyzes
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Characteristic signs
- Hypothyroidism
- Hyperthyroidism
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TSH lowered: treatment
- Treatment of central hypothyroidism
- Hyperthyroidism treatment
- Video
If thyroid-stimulating hormone is lowered - what does this mean for the body? The thyroid gland is an important endocrine organ in which thyroid hormones are produced. They are responsible for basic metabolism, affect the work of the heart and other organs. The thyroid stimulating hormone of the pituitary gland is responsible for the regulation of the thyroid gland. With various pathologies, its level can both increase and decrease. A decrease in the indicator may indicate a pathology of the thyroid gland, pituitary gland, hypothalamus. In all cases, treatment is required.
Thyroid function depends on the production of thyrotropin
The hormone TSH is lowered: what does it mean
Thyroid stimulating hormone (TSH) is produced in the anterior pituitary gland. He is responsible for regulating the thyroid gland. If the TSH is low, the thyroid gland is not stimulated, and the production of thyroid hormones stops.
The level of TSH in the blood is regulated by two mechanisms:
- Release factors that are produced in the hypothalamus. Under their influence, the pituitary gland is stimulated, and then increased TSH production.
- A negative feedback system. A decrease in the level of T3 and T4 stimulates the production of TSH, an increase in their level, on the contrary, inhibits.
There may be several reasons why a low TSH hormone is found, but they are all associated with damage to the thyroid gland, pituitary gland, or hypothalamus. There are three groups of diseases that can lead to this condition:
| Group of diseases |
Explanation |
| Thyroid pathology |
With hyperthyroidism, the production of thyroid hormones (T3, T4) increases. In this case, thyrotropin synthesis is suppressed by the negative feedback system. An increase in the level of thyroxine and triiodothyronine in the blood can occur for various reasons: With Graves' disease, the thyroid gland overproduces hormones. The disease is of an autoimmune nature and is more common in women. In acute and subacute thyroiditis, thyroid cells are destroyed and hormones are released into the blood. This leads to temporary hyperthyroidism. Uncontrolled intake of drugs, primarily Levothyroxine, can lead to hyperthyroidism. |
| Pituitary gland pathology |
Since thyrotropin is produced in the pituitary gland, a decrease in its level is often caused precisely by the pituitary pathology. The cause may be pituitary tumors (most often adenomas), Skien's syndrome (with severe postpartum hemorrhage), irradiation of the pituitary gland, surgical interventions in the pituitary gland. |
| Hypothalamic pathology | The pathology of the hypothalamus can lead to a violation of the regulation of TSH synthesis. This is the rarest group of causes. The condition can occur due to radiation therapy, certain medications, brain injury, and severe stress. |
Additional analyzes
Only a study of the level of thyrotropin is not indicative, the results obtained do not allow a diagnosis to be made.
Additionally, you need to investigate the level of thyroid hormones, at least free T4. According to the level of thyrotropin and thyroxine (T4), one or another pathology can be assumed.
| TSH | Free T4 | Presumptive diagnosis |
| Reduced | Promoted | An increase in T4 against a background of a reduced TSH level indicates overt hyperthyroidism. There may be several reasons for this; additional research is needed to clarify. |
| Reduced | Norm | A normal T4 level with a low TSH indicates latent hyperthyroidism. This means that the body is trying to compensate for the increased production of thyroid hormones. |
| Reduced | Reduced | The simultaneous decrease in T4 and thyrotropin indicates a central origin of hypothyroidism. This means that the thyroid gland cannot produce normal amounts of thyroid hormones. The reason for this condition lies in the defeat of the pituitary gland or hypothalamus. |
In addition, other studies may be prescribed to determine the cause:
- Ultrasound of the thyroid gland;
- analysis for antibodies to thyroglobulin;
- analysis for antibodies to thyroperoxidase;
- a test with thyroliberin (a positive test indicates a lesion of the hypothalamus, negative - a lesion of the pituitary gland);
- assessment of the level of other hormones (prolactin, FSH, LH, estradiol, testosterone).
Characteristic signs
By clinical manifestations, it is difficult to suspect a low thyroid-stimulating hormone. Symptoms are determined by the functional state of the thyroid gland. In some cases, there are no clinical signs of the disease at all.
Hypothyroidism
With central hypothyroidism, the following symptoms may develop:
- bradycardia - decreased heart rate;
- general weakness, lethargy;
- swelling, especially of the face;
- deterioration of cognitive ability - memory, attention;
- dry skin;
- dull and brittle hair;
- a tendency to constipation;
- delay in menstruation, lengthening of the menstrual cycle;
- a tendency to gain weight.
It is not at all necessary that they appear simultaneously. One of the symptoms can be observed, or several at once.
Hyperthyroidism
With hyperthyroidism, a clinical picture develops opposite to hypothyroidism. The following symptoms are characteristic:
- tachycardia - increased heart rate;
- diarrhea;
- losing weight despite increased appetite;
- warm and moist skin;
- increased sweating, heat intolerance;
- violation of the menstrual cycle.
With latent hyperthyroidism, symptoms may be completely absent. Any violations appear only when the state decompensates.
TSH lowered: treatment
Treatment for a low TSH level depends on the cause of the condition. In central hypothyroidism and hyperthyroidism, the treatment tactics are completely different. Therefore, it is not worth focusing only on the thyrotropin indicator when choosing a treatment.
Treatment of central hypothyroidism
In central hypothyroidism, therapy is substitutional. The introduction of TSH into the body is not carried out, those substances are prescribed, the synthesis of which is disrupted by a deficiency of TSH, that is, thyroid hormones.
For treatment, the drug Levothyroxine is used - free T4. The dosage is determined individually and depends on several factors - gender, weight, age, the presence of concomitant pathology.
Women under 50 years of age are prescribed 1.6-1.8 mcg / kg. On average, it is 75-100 mcg per day.
In old age, lower dosages are used, as the risk of complications from the cardiovascular system increases. Usually 0.9 mcg / kg is prescribed.
In the presence of cardiac pathology, the initial dose is 25 mcg per day. With good tolerance, the dosage is increased.
During pregnancy, the need for T4 increases, so the dose of Levothyroxine is increased.
When taking Levothyroxine, you need to control the level of T4 in the blood. The T4 concentration is maintained at a level that corresponds to the upper third of the normal values. In the treatment of central hypothyroidism, the change in TSH concentration is not significant.
Taking Levothyroxine helps to compensate for thyroid insufficiency
Hyperthyroidism treatment
Treatment for hyperthyroidism depends on the specific pathology. In most cases, thyrostatic drugs are used, which suppress the secretory activity of the thyroid gland.
The main thyrostatic drug is Mercazolil (Thiamazole), which inhibits the production of thyroid hormones. Thyrostatic treatment is effective, but not always safe for the human body. Dangerous side effects can develop:
- from the bone marrow - agranulocytosis, leukopenia, aplastic anemia;
- liver damage;
- allergic reactions;
- joint pain.
Less commonly, radioactive iodine or surgery is used for treatment.
In case of subacute and acute thyroiditis during the period of release of hormones from the cells into the blood, specific treatment is not applied. It makes no sense to prescribe thyrostatic drugs. In the future, with autoimmune thyroiditis, glucocorticosteroids are prescribed, with acute - antibacterial agents.
Video
We offer for viewing a video on the topic of the article.
Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
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