Venous blood test for TSH – Thyroid test
TSH (thyroid stimulating hormone) is a hormone produced by the pituitary gland and plays a central role in regulating the function of the thyroid gland. It works by stimulating the thyroid gland to produce and release the important hormones T3 (triiodothyronine) and T4 (thyroxine)**, which affect the body's metabolism, energy production and many other biological processes.
Analyzing the TSH level is crucial for detecting possible thyroid disorders, such as hypothyroidism (underfunction) and hyperthyroidism (overfunction), as well as for monitoring treatment in people with known thyroid disease.
Why analyze TSH?
A TSH analysis can be used for several purposes:
- Diagnose thyroid diseases – Detect both hypothyroidism and hyperthyroidism as well as autoimmune thyroid diseases such as Hashimoto's thyroiditis and Graves' disease.
- Check treatment effectiveness – People treated with thyroid hormones (e.g. Levaxin) or thyrostatics need regular monitoring of TSH levels.
- Monitor thyroid function – For people with a history of thyroid problems or an increased risk of thyroid disease, e.g. during pregnancy or heredity.
- Investigate symptoms of thyroid imbalance – Such as fatigue, weight changes, hair loss, chills, palpitations, mood swings and difficulty concentrating.
Reference values for TSH
TSH levels may vary slightly between laboratories, but generally the following reference ranges apply for adults:
- Normal TSH: 0.4 – 4.0 mIU/L
- Hypothyroidism (underfunction): TSH > 4.0 mIU/L
- Subclinical hypothyroidism: TSH 4.0 – 10.0 mIU/L with normal T3 and T4
- Hyperthyroidism (overfunction): TSH
It is important to interpret TSH values in combination with symptoms and, if necessary, supplement with analysis of free T3 (Triiodothyronine) and free T4 (Thyroxine) for a more accurate picture of thyroid function.
Factors that can affect TSH levels
TSH levels in the body can vary depending on several factors. High stress and poor sleep can affect thyroid function, which in turn can lead to altered TSH values. Pregnancy is another factor that can affect the level, and pregnant women often need careful monitoring because thyroid hormones play an important role in fetal development.
With increasing age, TSH levels can change naturally, and some individuals may experience a gradual increase without necessarily indicating a thyroid disease. Medications can also play a role, with cortisone, lithium and iodine supplements for example affecting thyroid function and thus TSH levels.
Autoimmune diseases such as Hashimoto's thyroiditis and Graves' disease can also cause changes in TSH levels by disrupting the normal regulation of thyroid hormones. Due to these many variables, it is important not to focus solely on the TSH level when evaluating thyroid function. A thorough assessment should always include clinical symptoms, other relevant hormones and any underlying medical conditions to ensure a correct diagnosis and treatment.
Testing TSH is an important part of evaluating thyroid function and diagnosing hormonal imbalances. Since the thyroid gland affects the entire body – from metabolism to heart function and mental health – a correct assessment of the TSH level can help detect and treat any disorders at an early stage.
If you suspect thyroid problems or want to follow up on your hormonal balance, it is recommended that you take a venous blood test for TSH. For a more comprehensive assessment, it may be valuable to also analyze T4, T3 and relevant antibodies.
