TSH, fT3, fT4
Thyroid Vital Check
The thyroid gland test measures the values of the parameters fT3, fT4 and TSH. These parameters are crucial for the assessment of thyroid function and the diagnosis of thyroid diseases such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). By measuring these hormone levels, possible disorders can be detected early and treated accordingly.
What is fT3?
fT3 (free triiodothyronine) is a form of the thyroid hormone triiodothyronine (T3) that is freely and biologically active in the blood. It plays a crucial role in regulating metabolism, body temperature, heart rate and growth. fT3 is an important measurement for assessing thyroid function.
What is fT4?
fT4 stands for free thyroxine, a hormone produced by the thyroid gland. It is the biologically active form of thyroxine (T4) and plays a crucial role in regulating metabolism, body temperature and growth. In contrast to bound T4, fT4 circulates freely in the blood and is directly available for hormonal activity.
What is TSH?
TSH (thyroid-stimulating hormone) is a hormone produced by the pituitary gland (hypophysis). It regulates the function of the thyroid gland by stimulating the production and release of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). These hormones are crucial for metabolism, growth and development of the body.
For whom is such a test to be considered?
A thyroid test is particularly suitable for people who exhibit symptoms of a thyroid dysfunction. These include:
- Fatigue
- Weight gain or loss
- Sensitivity to cold or heat
- Hair loss
- Irregular heartbeat
- Changes in the menstrual cycle
- Nervousness and trembling
The test is also relevant for people who already have a known thyroid disease or in whom the suspicion of such a disease exists.
What is it used for?
The thyroid test is used to evaluate the function of the thyroid gland and to diagnose disorders such as hypothyroidism or hyperthyroidism. It helps to determine the extent and cause of the thyroid dysfunction and to monitor the effectiveness of thyroid hormone therapy.
What can be derived from it?
- A low fT3 or fT4 level may indicate hypothyroidism.
- A high fT3 or fT4 level may indicate hyperthyroidism.
- An elevated TSH value usually indicates hypothyroidism, as the pituitary gland tries to stimulate the thyroid gland to produce more thyroid hormones.
- A low TSH value may indicate hyperthyroidism, where the thyroid gland produces too many hormones and the pituitary gland therefore releases less TSH.
Abnormal values of these parameters should be further investigated through additional diagnostic measures and in consultation with a physician.
What is the ideal time for testing?
The thyroid test can be performed at any time of the day, as the values of the hormones fT3, fT4 and TSH in the blood are relatively stable. However, it is recommended to perform the TSH test in the morning, as the TSH concentration is highest at this time.
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Fragen und Antworten zu Freies T4 (fT4)
What is the respective laboratory value?
Free T4 (fT4) is the biologically active form of the thyroid hormone thyroxine, which is produced directly by the thyroid gland. The laboratory value measures the concentration of the unbound (free) T4, which enables the conversion to T3 in the body.
For whom is such a test to be considered?
A fT4 test is recommended for: People with symptoms of thyroid dysfunction (e.g. weight gain, hair loss, insomnia) Individuals with abnormal TSH levels for further investigation Pregnant women or women planning a pregnancy, as thyroid function affects fertility Patients suspected of conditions like Hashimoto's thyroiditis or Graves' disease Monitoring of thyroid hormone replacement therapy
What is it used for?
The test serves to clarify thyroid diseases and to assess thyroid function. It is often performed together with TSH and fT3 to obtain a complete picture.
What can be inferred from that?
An elevated fT4 value indicates an overactive thyroid, which can be characterized by: Nervousness, trembling Insomnia and palpitations Unintentional weight loss. A low value can indicate an underactive thyroid, with symptoms such as: Fatigue, sensitivity to cold Weight gain Dry skin and constipation.
What is the ideal time for a test?
The testing can be carried out at any time of the day, but ideally fasting in the morning to minimize possible influences of medications.
Particularly interesting?
The text translated to English is: fT4 is less susceptible to short-term fluctuations than TSH and therefore provides a more stable statement about thyroid function. The test should be interpreted in conjunction with TSH, as fT4 alone does not allow for a complete diagnosis. Significant weight fluctuations, iodine deficiency or excess can affect the values.
Fragen und Antworten zu Freies T3 (fT3)
What is the respective laboratory value?
Free T3 (fT3) is the biologically active form of the thyroid hormone triiodothyronine, which is formed in the thyroid follicles from thyroxine (T4). The laboratory value measures the concentration of the unbound (free) T3 in the blood, which is directly available for metabolism.
For whom is such a test to be considered?
A fT3 test is recommended for: Patients with symptoms of thyroid over- or underfunction (e.g. nervousness, palpitations, weight fluctuations) People with conspicuous TSH values for further clarification Patients with suspected specific thyroid diseases such as Graves' disease Persons with thyroid nodules or other structural changes in the thyroid Monitoring of thyroid function during therapy or after an operation
What is it used for?
The test is used to assess thyroid function and to differentiate thyroid diseases. It helps to distinguish between a compensated and a decompensated thyroid hyperfunction.
What can be inferred from that?
A high fT3 value can indicate an overactive thyroid (hyperthyroidism), which can cause symptoms such as: Nervousness, trembling Rapid heartbeat and sweating Weight loss despite increased appetite A low value indicates an underactive thyroid (hypothyroidism), which can be characterized by: Fatigue, weight gain Sensitivity to cold and dry skin.
What is the ideal time for a test?
The test can be performed at any time of the day, as the concentration of fT3 does not exhibit a strong circadian rhythm. For patients with fluctuating symptoms, repeated testing may be useful.
Particularly interesting?
fT3 is often tested together with TSH and fT4 to obtain a complete picture of thyroid function. Certain medications (e.g. amiodarone, corticosteroids) and diseases can influence the conversion of T4 to T3 and thus change the values.
Fragen und Antworten zu TSH
What is the respective laboratory value?
TSH is a hormone that is produced in the pituitary gland (pituitary gland) and stimulates the thyroid gland to produce the hormones T3 (triiodothyronine) and T4 (thyroxine). The laboratory value measures the concentration of TSH in the blood and is used to assess thyroid function.
For whom is such a test to be considered?
A TSH test is recommended for: Persons with symptoms of an over- or underactive thyroid gland (e.g. fatigue, weight fluctuations, palpitations) People with a family history of thyroid disorders Women with unfulfilled desire to have children or miscarriages Monitoring of thyroid function during drug therapy or after an operation Newborns, to rule out congenital thyroid disorders
What is it used for?
The test serves the diagnosis and monitoring of thyroid diseases such as hypothyroidism (underfunction) and hyperthyroidism (overfunction). It is also a screening test for the detection of subclinical thyroid disorders.
What can be inferred from that?
A high TSH value indicates an underactive thyroid, which can cause symptoms such as fatigue, weight gain, and sensitivity to cold. A low value indicates an overactive thyroid, which can be accompanied by symptoms such as nervousness, rapid heartbeat, and weight loss.
What is the ideal time for a test?
The test can be performed at any time of the day, however, TSH values show a slight circadian rhythm, with peak values in the early morning hours.
Particularly interesting?
The TSH values should be interpreted in connection with the thyroid hormones T3 and T4. Certain medications and iodine intake can affect the TSH value. TSH is often used as the first test when suspecting thyroid disorders, as it reacts very sensitively to changes in thyroid function.