La TSH (for thyroid stimulating hormon), also called hormone thyréostimulante ou thyroid stimulating hormone, is a hormone made bypituitary gland, in the brain. It regulates the secretion of the hormones T4 and T3 by the thyroid, a gland located at the base of the neck.

These thyroid hormones themselves exert a control over the secretion of TSH (this is called negative feedback): the less there is circulating thyroid hormones, the more the secretion of TSH increases, to stimulate the thyroid. Thus, halving the T4 in the blood increases the TSH concentration by 100!

The TSH test is the best indicator to assess a thyroid disease. It allows to :

• diagnose a hyper or hypothyroidism
• help clarify the cause of the condition (autoimmune, genetics, etc.)
• monitor thyroid disease and the effectiveness of treatment

The TSH assay can therefore be performed in people with various symptoms (such as cramps, skin dryness, chilliness, fatigue or lack of energy, insomnia, anxiety, depression, etc. ), but also at:

• people with goiter
• people without symptoms who have an autoimmune disease (type 1 diabetes, rheumatoid arthritis, etc.)
• patients treated with drugs likely to cause thyroid dysfunction (lithium carbonate, interferon, etc.)
• for an assessment in women over 50 (sometimes even recommended from 35 years old every 5 years)
• patients with dyslipidemia or high blood pressure (initial assessment of hyperlipidemia)
• if you have a family history of thyroid disease

The determination of free T4 is sometimes performed as a second step in the event of an abnormal TSH level.