TSH test

The TSH test is one of the basic tests which check the proper functioning of the thyroid gland. In practice, a physician may prescribe the TSH test when s/he suspects hypo- or hyperthyroidism, or as part of monitoring the treatment efficiency.

What does the TSH test involve?

The easiest way to diagnose hyperthyroidism is to check the TSH concentration in the blood. If the result indicates that this concentration is below the lower limit of the norm, it is clear that we have hyperthyroidism.

The norms may slightly differ from one another. This depends on the reagent and apparatus used by laboratory technicians, as well as the technique of the test in a given laboratory. If the results are out of the normal range, it is recommended to consult a physician who can decide that further diagnostic measures are necessary, e.g. checking the level of free thyroxine – one of the thyroid hormones in the human body.

Decreased TSH concentration levels along with increased fT4 values indicate the presence of hyperthyroidism. Based on the results of existing tests and examinations, the medical history and the examination during an appointment, a physician may prescribe additional tests and examinations to find the cause of the diseases, for example:

• ultrasonography of the thyroid gland
• complete blood count
• sssessing the level of anti-thyroid autoantibodies

The best method for diagnosing hypothyroidism is to collect a blood sample from the patient. If the result exceeded the upper limit, the case must be consulted with a physician. The norms usually differ from one another, as in the case of hyperthyroidism. Moreover, it may happen that the physician will prescribe us the TSH test to control the treatment effectiveness.

What is TSH?

Thyrotropin is a hormone produced by the anterior pituitary gland.

This hormone is responsible for:

• regulating thyroid hormone functions,
• stimulating the formation and secretion of thyroxine and triiodothyronine,
• increasing the speed of metabolic processes occurring in the thyroid gland.

TSH – preparation for the test

The test requires collecting a blood sample from the patient in the morning hours.

Why is the blood collected in the morning?This is because the human circadian rhythm plays an essential role in hormonal tests.

How to prepare for the test

The test requires no special preparation. It is not recommended to use a special diet or take drugs before the blood collection procedure. Any cases of malaise after sample collection should be notified to a physician or a nurse. This condition results from the vasovagal reaction. Please remember that the amount of blood collected is very small and should not significantly impact the patient’s well-being.

Is the TSH test performed on an empty stomach?

There is no need for the patient to be on an empty stomach. In the event of blood glucose tests or leukocytes in complete blood count, no meals can be consumed for 8-12 hours before blood collection. Each blood test is always accompanied by a prescription from a physician. Therefore, the preparation for the TSH test is not problematic. All that needs to be remembered is the morning hour of blood sample collection and consultation of the morning intake of drugs with a physician.

Medication use vs the TSH test

Prior to blood collection, it is necessary to inform the person collecting the blood sample about the drugs, herbs and dietary supplements we take and which may affect the blood test results. In the event of regular drug use, the decision on blood collection before taking the morning dose of drugs should be consulted with a physician.

Immediately before blood collection, it is forbidden to take over-the-counter drugs, such as Ibuprom and others. In the event of regular drug use, a physician may order that the blood be collected at a specific time interval from drug intake. In such situations, the decision on blood collection is made by a physician.

TSH norms

The proper values of the thyroid-stimulating hormone (TSH) in the blood range from 0.2–0.4 to 4.0–4.25 mj.m. for an adult individual. Nevertheless, it should be remembered that these norms are not permanent. They may also differ due to the methodology adopted by a given laboratory.

TSH above the normal range

Such a result usually indicates hypothyroidism. Sometimes, high levels of the thyroid-stimulating hormone (high TSH) indicate the presence of hypophysial adenoma (adenoma of the pituitary gland), genetic diseases or primary adrenal insufficiency, or result from the intake of certain drugs (e.g. thyreostatics).

TSH below the normal range

Lowered results indicate hyperthyroidism. Sometimes, they are also related to hypopituitarism or Graves-Basedow disease. Moreover, low TSH values tend to result from the intake of specific agents (e.g. dopamine, phenytoin, or amiodarone).

The thyroid gland – functions and characteristics

Despite its small size, the thyroid gland is responsible for:

• T4 and T3 hormone production;
• Metabolic regulation;
• It affects the functioning of the circulatory system.

The 2006 data of the Polish Central Statistics Office (GUS) demonstrate that statistically every fifth person in Poland had or still has thyroid problems. Many of them fail to see the changes occurring in the body or simply ignore certain symptoms. If you have noticed that your skin has become dry, you feel cold, cannot lose or gain any weight – go to a physician who will use your medical history and examination to make a diagnosis or prescribe additional tests/examinations. Simple blood tests make it possible for a physician to determine whether the thyroid gland produces adequate amounts of hormones.

TSH during pregnancy

Why is the TSH test prescribed during pregnancy? Thyroid hormones are necessary for proper growth of the foetus. Their proper levels determine healthy growth of the brain, as well as the nervous and skeletal systems. The test itself is prescribed in individuals with suspected hyper- or hypothyroidism. During pregnancy, oestrogen and chorionic gonadotropin (hCG) may increase or decrease the production of the thyroid-stimulating hormone (TSH).

How often should the TSH be checked during pregnancy?

Depending on which trimester the woman is in, the range of the norm for TSH may deviate from the standard one. An increased production of thyroid hormones in women generates the demand for iodine. In the event of abnormal TSH values, further procedures, including the frequency of follow-up appointments, are determined by an endocrinologist. Hypothyroidism in pregnant women may increase the risk of miscarriage or premature childbirth.

Hypothyroidism and hyperthyroidism

Hypothyroidism is one of the most common conditions affecting the thyroid gland: The manifestations of hypothyroidism include:

• increased body mass;
• weakening, easy fatigue during exercise, general fatigue;
• excessive drowsiness;
• concentration problems;
• memory disorders;
• feeling of cold, fast freezing (especially of the hands and feet, usually in the afternoon and evening);
• constipation;
• dried skin;
• oedema of the eyelids and hands, thickening of facial features;
• dry and fragile hair;
• hoarseness and husky voice.

Good treatment results are offered by levothyroxine, whose effects are the same as those of the thyroid-produced hormone. It is recommended to follow a healthy, well-balanced diet, rich in adequate amounts of proteins, carbohydrates and fats. Hyperthyroidism commonly affects women at the age between 20 and 40 years.

The symptoms of hyperthyroidism, on the other hand, are as follows:

• weight loss, despite increased appetite;
• feeling of heat;
• hyperhidrosis (excessive perspiration);
• irritability, nervousness, restlessness, anxiety;
• insomnia;
• concentration difficulties;
• trembling of the hands, tongue or eyeballs;
• increased bowel movements, and even diarrhoea;
• accelerated heart rate, palpitations;
• dyspnoea;
• decreased muscle strength;
• hair loss;
• symptoms typical of Graves-Basedow disease: protrusion of the eyeballs, double vision, oedema or reddening of the eyelids or conjunctivae;
• in women - menstrual disorders (dysmenorrhoea), including rare or absent menstruation;
• in men - decreased libido and sometimes erectile dysfunctions.

A physician prescribes drugs that reduce the production of thyroid hormones. Quick detection of problems may protect us against complications, including cardiac arrhythmias or heart failure.