Thyroid hormones which causes the thyroid to enlarge (the resulting medical condition is called "endemic colloid goitre"; see goitre). This has the effect of increasing the thyroid's ability to trap more iodide, compensating for the iodine deficiency and allowing it to produce adequate amounts of thyroid hormone. Most of the thyroid hormone circulating in the blood is bound to "transport protein"s. Only a very small fraction of the circulating hormone is free (unbound) and biologically active, hence measuring concentrations of free thyroid hormones is of great diagnostic value. When thyroid hormone is bound, it is not active, so the amount of free
Pseudo-goitre attached to the thyroid such as a true goitre, also moves along with thyroid. A pseudogoitre is unlikely if the area of fullness moves with swallowing. If pseudogoitre is due to cervical lordosis, the fullness disappears on straightening of the neck. A high-lying thyroid can be excluded by palpation. If the diagnosis is uncertain after clinical examination, an ultrasonogram is taken to rule out pathology of the neck. Pseudo-goitre Pseudo-goitre is the apparent fullness of the front part of the neck. It may be mistakenly diagnosed as thyroid enlargement. The cause for pseudogoitre can be fat tissue of the neck,