TSH and thyroid

As an indicator of thyroid function, the value of the hormone TSH can be analyzed by common blood tests.

Known as thyroid stimulating hormone (TSH, also known as thyrotropin or thyrotropin), this substance serves as an indicator for thyroid health. When alterations in its values are observed, which are too high or too low, the cause is probably one of the pathologies of the thyroid gland.

What is it?

It is a hormone produced by the pituitary, or pituitary gland, a small gland located in the center of the skull and represents the real functional nucleus of the endocrine system. Its role is to regulate the function of the thyroid, which is located at the base of the neck. In particular, the pituitary regulates the production of thyroid hormones: trioiodothyronine (T3 or fT3) and thyroxine (T4 or fT4).

Each of these substances is present in two forms:

  • a circulating free form (fT3 and fT4), which is active and available to various tissues of the body
  • a form linked to plasma proteins (T3 and T4), which represents the reserve of these substances, which will be released and made available in case of need of the body’s cells.

What is TSH used for?

TSH therefore plays a crucial role in the regulation of our metabolism, influencing:

  • brain development;
  • breathing;
  • the cardiovascular system and, in particular, the heart;
  • the functions of the nervous system;
  • body temperature;
  • muscle strength;
  • preparation and resistance to effort;
  • dry skin;
  • menstrual cycles;
  • weight;
  • cholesterol levels.

Alterations in TSH levels, and therefore of the hormones T3 and T4, cause various hormonal disorders and symptoms among the most varied, which manifest themselves differently depending on the subjects affected, but which are often particularly heavy in everyday life and, most of the time, require special medical treatment.

TSH and thyroid hormones

The thyroid gland is under strict hormonal control by the pituitary, which acts by TSH. Under normal conditions, when circulating levels of thyroid hormones are lowered, the pituitary gland produces additional amounts of TSH, which in turn stimulates the thyroid gland to produce T3 and T4.

When the amount of hormones in circulation is sufficient for the body’s functions, the pituitary gland “rests” the thyroid, reducing stimulation through TSH. The thyroid gland then responds by decreasing the synthesis of T3 and T4.

It is a simple and perfect mechanism that, however, sometimes jams; a problem in this natural cycle can lead, for example, to an excessive decrease in the synthesis of T3 or T4, or, on the contrary, can lead to the stimulation of an overabundant production. This is what occurs when thyroid disorders develop, which represent a subject of study for endocrinology, a specific branch of medicine.

How to read TSH levels?

If the doctor suspects thyroid disease, he will prescribe tests to the patient: these are simple laboratory tests and precisely blood tests to evaluate the values of thyroid hormones.

First, the TSH dosage is carried out, which is a test to evaluate the levels of TSH in circulation. In the presence of abnormalities in the normal values of this substance, the doctor will order further tests to understand what are the causes of these alterations, such as:

– T3 and T4 levels,

– the presence of anti-thyroid antibodies, which attack the thyroid gland;

– the values of TSI, or thyrostimulating immunoglobulin, an antibody that mimics the function of TSH, stimulating the action of the thyroid.

In addition to the common blood tests that can be performed in any analysis laboratory, there are other procedures to help diagnose a thyroid disease, including:


– CT, computed axial tomography;

– scintigraphy of the gland;

– the uptake of radioactive iodine.

The latter is a nuclear medicine test used to evaluate the functionality of the thyroid gland, diagnose a possible pathology and, consequently, find the cause of hyperthyroidism (it is not, however, used for the evaluation of hypothyroidism). The test measures the amount of circulating iodine taken up by the thyroid in a given period of time.

When TSH is too high…

If, based on the outcome of the relevant tests, the patient’s clinical picture shows that this protein is present at levels and concentrations above normal, it is very likely that we are faced with a case of hypothyroidism, a situation in which the thyroid works less than necessary. Thyroid hormone levels will then be lower than normal.

This situation is not always accompanied by symptoms. In some cases, in fact, hypothyroidism can be subclinical, that is, not showing signs of its presence. In this case the TSH value will still be high, while the thyroid hormones will still be normal.

If they occur, usually the most common symptoms, although variable from patient to patient, are:


– weight gain;

– intolerance to cold;

– joint and muscle pain;


– hair loss;

 in women, copious or irregular menstrual cycles and difficulty in becoming pregnant;


– memory deficit;

– slowing of the heart rate (bradycardia).

In this case, the presence of an underlying thyroid-type disorder is highly likely, and it is advisable to consult professionals for more in-depth visits and constant monitoring. To make a precise diagnosis, however, it is essential to measure, through a blood sample, also the levels of thyroid hormones T3 and T4 and antithyroid antibodies. In fact, there is another pathology, Hashimoto’s thyroiditis, which is characterized by high TSH values and similar symptoms, when present.

The latter differs from hypothyroidism in that:

– levels of hormones T3 and T4 are elevated;

– anti-thyroid antibodies are present.

This disease, also known as chronic lymphocytic thyroiditis, is an autoimmune disease: the immune system does not work as it should and produces antibodies against the thyroid, which, therefore, in fact, works less efficiently than normal.

Goiter and high TSH

High TSH levels therefore indicate poor thyroid functioning. Often, this phenomenon is accompanied by the appearance of goiter, a disease that affects almost 6 million people in Italy: the thyroid gland increases in size and is visible in the form of swelling at the level of the neck.This disorder occurs due to a deficiency of thyroid hormones circulating in the body, which are produced in small quantities. As a result, the levels of the TSH hormone increase and therefore the demand for hormone production towards the thyroid increases, which, to meet the increased demand for T3 and T4, undergoes excessive work. This, in turn, results in the increase in the number of cells and the visible enlargement of the organ in question.

What to do in case of hypothyroidism?

Unfortunately, to date there is no definitive cure for hypothyroidism, nor is it possible to safely prevent its most serious effects without pharmacological treatment. However, thanks to the results of decades of clinical research and scientific studies, living peacefully with this disease is now possible for almost all patients.

In most cases, your doctor will recommend that you follow replacement therapy. In other words, the therapeutic approach consists of providing the body with hormones that the thyroid can no longer produce in the right amount, thus bringing T3 and T4 back to normal levels. Thus, even if this organ does not work well, the administration of a thyroxine analogue can restore thyroid hormone levels and body functions to normal.

Replacement therapy is based on drugs that contain the same hormone that the body cannot produce, namely thyroxine. Depending on the severity of the disease, the doctor will choose not only the most correct type of supplements, but also the dosage that best suits the patient’s needs.

It must be taken into account that this type of diseases are chronic conditions, which, therefore, do not have acute phases that require, for example, hospitalization or urgent therapy, but, on the contrary, last for several tens of years, accompanying patients for most of their lives.

Given the long duration of therapies, it is likely that the dose of thyroxine may need adjustment. By scrupulously following the doctor’s indications, however, it is possible to completely control the disease and the symptoms can stop getting worse or even improve: only with the constancy in continuing the therapy prescribed by the specialist or by your doctor you can get lasting results.

When TSH is too low

In the event that the TSH values are too low, however, the cause is usually hyperthyroidism. In the presence of this disorder, it is as if the thyroid pushes our metabolism to the maximum, functioning more quickly than normal.

The symptoms are unexplained weight loss despite a good appetite, irritabilityinsomnia and hyperactivity (the patient finds difficulty in relaxing, feeling full of “nervous” energy and therefore almost forced to always be active), accelerated heart rate (tachycardia), palpitationsincreased sweatingtremor in the handsanxietymood changes sensitivity to heatvery fragile hair and nailsmuscle weakness, especially in the upper arms and thighs, frequent bowel movements, although diarrhea is rare, itching and/or hives, reduced sexual desirereduced flow and frequency of menstruation.

Even in this case, however, it is important to make a precise diagnosis and, to do so, it is necessary to evaluate other parameters, such as:

– the levels of hormones T3 and T4;

– the uptake of radioactive iodine;

– the level of TSI,

– the presence of anti-thyroid antibodies.

In fact, there are other diseases that can cause an increase in TSH levels, such as pituitary problems, Graves’ disease and thyroid nodules. The following table summarizes their respective characteristics.

Pituitary problems Low levels of T3 and T4

Absence of anti-thyroid antibodies

Graves’ disease High levels of T3 and T4

Presence of TSI

High uptake of radioactive iodine

Thyroid nodules Normal levels of T3 and T4


Normal uptake of radioactive iodine

What to do in case of hyperthyroidism?

Hyperthyroidism is a chronic condition that can evolve over time. The doctor will choose the most appropriate treatment for the situation of each individual patient, setting up a personalized therapy to be followed scrupulously.

The choice of care is influenced by age, severity of the pathology and the presence or absence of other medical conditions that affect the patient’s health.

Among the therapeutic possibilities are:

– antithyroid drugs and beta-blockers (whose effectiveness must be verified in the short, medium and long term);

– radioactive iodine;

– surgery for the removal of the gland (it being understood that the use of surgery should always be the last resort, to be used only in the case of very high grade thyroid diseases that do not respond to other treatments).

Those suffering from hyperthyroidism, moreover, should try to fight it even at the table. It is good to limit the consumption of alcohol, chocolate and caffeinated beverages (tea, coffee and cola), follow a healthy and balanced diet and avoid extreme diets (for example those that involve fasting or various forms of abstention from certain nutrients), especially if you suffer from diabetes or similar diseases that interfere with the body’s metabolic mechanisms.

Joycelyn Elders is the author and creator of EmpowerEssence, a health and wellness blog. Elders is a respected public health advocate and pediatrician dedicated to promoting general health and well-being.

The blog covers a wide range of topics related to health and wellness, with articles organized into several categories.

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