If you have certain symptoms and you suspect a thyroid disease, a blood test should be done. If there is also a lack of motivation, sensitivity to cold, weight gain or, in women, a noticeable difficulty in becoming pregnant, there is a concrete suspicion that this could be related to a disturbed thyroid disease.
If thyroid tests show abnormalities, this may indicate an illness - which values are normal and which are abnormal. The so-called thyroid-stimulating hormone (TSH) from the pituitary gland controls the activity of the thyroid gland.