FT3 and FT4 test at OpenMed Warsaw
The FT3 and FT4 test is one of the basic laboratory tests used in the diagnosis of thyroid diseases. It allows assessment of the concentration of free thyroid hormones in the blood, which are responsible for the proper functioning of many processes taking place in the body. If you notice chronic fatigue, sudden changes in body weight, heart palpitations, or problems with concentration, it is worth considering hormone tests. At OpenMed in Warsaw (Wola), you can have the FT3 and FT4 test done together with the option of a medical consultation and interpretation of the results.
The thyroid is a small gland located in the front part of the neck, yet its influence on the body is very significant. The hormones it produces regulate metabolism, body temperature, the work of the cardiovascular system, the functioning of the nervous system, and the body's energy balance. Disturbances in their concentration can lead to both hypothyroidism and hyperthyroidism.
What are the FT3 and FT4 hormones?
FT3 (free triiodothyronine) and FT4 (free thyroxine) are the biologically active fractions of the hormones produced by the thyroid. The designation "FT" comes from the English word "free," meaning unbound. This means that the test assesses hormones not bound to transport proteins, which are available to cells and directly affect the functioning of the body.
FT4 is the hormone produced by the thyroid in the largest amount and is the source for FT3, which is biologically more active. Analysis of both parameters, most often together with a TSH test, allows the doctor to assess thyroid function more accurately and to detect any abnormalities.
When is it worth having an FT3 and FT4 test?
The FT3 and FT4 test is performed both in first-time diagnosis and during the monitoring of thyroid disease treatment. The doctor may recommend the test in the case of symptoms suggesting hormonal disorders or abnormal TSH results.
The most common indications include:
- chronic fatigue, drowsiness or weakness,
- sudden weight gain or loss without a clear cause,
- heart palpitations, excessive sweating or a feeling of anxiety,
- problems with concentration, memory and mood,
- diagnosis and monitoring of treatment for hypothyroidism or hyperthyroidism.
The test is also frequently performed in women planning a pregnancy, during pregnancy, and in people diagnosed with autoimmune thyroid diseases such as Hashimoto's disease or Graves-Basedow disease.
What does an FT3 and FT4 test look like?
The test involves taking a venous blood sample. It is a quick and safe procedure that takes only a few minutes. In most cases, it is recommended to have the test done in the morning. If the patient takes hormonal medications used in thyroid treatment, it is worth consulting the doctor in advance about how to prepare for the test.
After collection, the sample is sent to the laboratory, where the concentration of FT3 and FT4 is determined. Results are always interpreted in relation to laboratory reference ranges and the patient's clinical situation. The result alone should not be the basis for making a diagnosis on your own.
Interpretation of results and further diagnostics
Abnormal FT3 and FT4 values may indicate various thyroid disorders. Elevated concentrations are most often observed in hyperthyroidism, while lowered ones may suggest hypothyroidism. In practice, the doctor analyses the results together with the TSH level, the patient's symptoms, and additional tests such as thyroid antibodies or a thyroid ultrasound.
At OpenMed, you can have the FT3 and FT4 test done and consult the result with a doctor. This makes it possible to quickly start further diagnostics or treatment if needed.
FT3 and FT4 test - FAQ
It is not necessary, but in most cases it is recommended to have blood drawn in the morning. It is worth asking your doctor or the blood collection point in advance about the specific recommendations.
FT3 and FT4 are hormones produced by the thyroid, while TSH is a hormone of the pituitary gland that regulates the work of the thyroid.
The test assesses thyroid function, however, in the diagnosis of Hashimoto's disease, anti-TPO and anti-TG antibodies are usually also measured and a thyroid ultrasound is performed.
The waiting time depends on the laboratory, but the results are most often available within 1-2 business days.
Most often when hypothyroidism or hyperthyroidism is suspected, during treatment monitoring, and in the diagnosis of hormonal disorders.