What’s TSH (Thyroid Stimulating Hormone)

What’s TSH (Thyroid Stimulating Hormone)

What’s TSH, and How it looks like?

The thyroid gland is a small gland, about 5 cm in size, located under the skin under Adam’s apple in the neck. The two parts of the gland connect in the middle in an area called the isthmus, which gives the thyroid gland the shape of a small tie. The thyroid gland usually cannot be seen and can hardly be felt. But if it is enlarged (goiter), doctors can handle it quickly, and it may appear as a prominent bulge at the bottom or sides of Adam’s apple.

The thyroid secretes the hormones of the thyroid and regulates the metabolism of the body. Two different approaches control the synthesis of thyroid hormones:

  • By promoting the production of protein by all body tissues
  • The oxygen used in cells rises
  • Thyroid hormones influence many of the body’s vital functions: heart rate, calorie, skin repair, development, heat, fertility, and digestion.

The brain and Pituitary gland hormones influenced organs. Detailed illustration.

Thyroid hormones

They are two hormones of the thyroid gland

  • T4 (thyroxine, or tetraiodothyronine).
  • T3 (triiodothyronine).

T4 is the primary hormone produced by the thyroid gland. It has only a slight effect on accelerating the metabolism (metabolism) in the body, and it may not affect it. Whereas, T4 is converted into T3, which is the most active hormone. The conversion of T4 to T3 occurs in the liver and other body tissues. Several factors control the conversion of T4 to T3, including the body’s different needs from one moment to the next, and the presence or absence of diseases. Most of T4 and T3 are carried into the bloodstream by a protein called thyroxine-binding globulin. Only a small amount of T4 and T3 is freely present in the blood. It is this free part of the hormone that is active. When the body uses the free hormone, more of it is released by the thyroxine-bound globulin.

To make the two thyroid hormones, the thyroid gland needs iodine, which is found in food and water. The thyroid gland stores iodine and processes it to convert it into a thyroid hormone. With thyroid hormones, some of the iodine in those hormones is released, then back into the thyroid gland, and recycled to produce more thyroid hormones. The strange thing is that the thyroid gland releases fewer thyroid hormones if exposed to high levels of iodine transported to it through the blood.

So, there is a complex mechanism that controls the levels of thyroid hormones in the body. First, the hypothalamus, located just above the brain’s pituitary gland, secretes the hormone thyrotropin, which prompts the pituitary gland to produce thyroid-stimulating hormone (TSH). TSH helps the thyroid gland to produce thyroid hormones, as the name implies. The pituitary gland slows or speeds up the release of thyroid-stimulating hormone (TSH), depending on whether thyroid hormones in the blood are too high or too low.

The thyroid gland also produces the hormone calcitonin, which may enhance bone strength by introducing calcium into the bones.

Signs and symptoms of hypothyroidism:

Fatigue, increased sensitivity to cold, constipation, dry skin, weight gain, facial swelling, hoarseness, muscle weakness, high blood cholesterol, muscle aches, pain, and stiffness, joint pain, stiffness, or swelling, heavier menstruation than usual, or Irregular periods, hair loss, slow heart rate, depression, memory impairment, an enlarged thyroid gland (goiter).

Diagnostic tests

First, the doctor examines and feels the patient’s neck to check whether the thyroid gland is enlarged or not.

Another testing may also be required depending on the outcome of the evaluation. Rare cases, additional tests may be necessary when doctors cannot determine whether the problem is in the thyroid gland or the pituitary gland.

Thyroid function tests

To evaluate the thyroid gland’s proper functioning, doctors usually measure the levels of hormones in the blood. These tests measure each of the following hormones:

  • TSH
  • T4
  • T3

The level of TSH in the blood is usually the best indicator of thyroid gland function. Since TSH stimulates the thyroid gland, TSH’s high blood levels indicate that the thyroid gland is underactive (and therefore needs more stimulation). In contrast, TSH’s low blood levels indicate that the thyroid gland is overactive (and thus needs less motivation). However, in rare cases, when the pituitary gland does not function normally, TSH levels may not accurately reflect the thyroid gland’s function.

When doctors measure the thyroid hormones T4 and T3 in the blood, they usually measure the stories of the free and associated forms of each hormone (total T4 and total T3). However, suppose the levels of thyroxine-associated globulin are abnormal. In that case, the entire thyroid hormone levels may be misinterpreted, so doctors may sometimes measure the levels of free hormones in the blood. The story of thyroxine-bound globulin is lower in patients who have kidney disease or diseases that reduce the amount of protein made by the liver, or in people who are taking anabolic steroids. Whereas, levels of thyroxine-bound globulin are higher in pregnant women or who use birth control pills or other forms of estrogen, and in those with early-stage hepatitis.

Thyroid gland imaging

If a doctor feels that there are single or multiple growths (nodules) in the thyroid gland, they may order imaging of the thyroid gland. Ultrasound is used to measure a gland’s size and determine whether the growth is substantial or fluid-filled (cystic).

In another type of thyroid imaging (called a radioiodine absorption test), a small amount of radioactive iodine or technetium is injected into the bloodstream. The radioactive material is concentrated in the thyroid gland. Then a special camera (gamma camera) is used that can detect the radiation released, which leads to the formation of an image of the thyroid gland that shows any abnormalities in its structure.

Thyroid imaging may also help determine whether a specific part of the thyroid gland is functioning normally, is overactive, or poorly compared to the rest of the gland.

Analyze thyroid scan results

High level

Some laboratories initially check the general level of thyroid hormone, and only if it is high – check the status of free thyroid hormone.

High thyroid hormone level:

  • Hyperthyroidism
  • Acute thyroiditis

In the following cases, the general T4 level may be high, but the free T4 level (FT4) is healthy:

  • Viral hepatitis (Hepatitis)
  • Muscle weakness (myasthenia gravis)
  • Pregnancy
  • Introduction to eclampsia (preeclampsia)
  • Take medications
  • Low thyroid hormone level:
  • Hypothyroidism (hypothyroidism)
  • Insufficient pituitary gland (hypopituitarism)

Take medications

Medicines that may cause an increase in the general T4 level:

  • estrogen-containing birth control pills
  • clofibrate (a lipid-lowering drug – Clofibrate)
  • perphenazine (a sedative and antipsychotic medication – Perphenazine)

Medicines that may cause general T4 decline: high doses of salicylates, corticosteroids, Chlorpromazine, Phenytoin, Heparin, Lithium, Sulfonamides, Reserpine Testosterone, Propranolol, and Tolbutamide.

Sound results

T4 hormone

65 – 160 nmol per liter

4,5 – 12.5 micrograms per deciliter (Micrograms per deciliter)

FT4 hormone

10 – 25 picomol liter

0,8 – 3,3 g per deciliter (Nanograms per deciliter)

In women

The right results:

T4 hormone

65 – 160 nmol per liter

4,5 – 12.5 micrograms per deciliter (Micrograms per deciliter)

FT4 hormone

10 – 25 picomol liter

0,8 – 3,3 ng per deciliter (Nanograms per deciliter)

In children

Sound results

The T4 level in newborns ranges from 10 – 25 micrograms per deciliter; In infants up to the age of one year: 7-16 micrograms per liter, and for those over ten years old, the hormone level is similar to that in an adult:

T4 hormone

65 – 160 nmol per liter

4,5 – 12.5 micrograms per deciliter (Micrograms per deciliter)

FT4 hormone

10 – 25 picomol liter

0,8 – 3,3 nanograms per deciliter (Nanograms per deciliter)

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