Goitre contributing factor. In countries that use iodized salt, Hashimoto's thyroiditis is the most common cause. Goitre can also result from cyanide poisoning; this is particularly common in tropical countries where people eat the cyanide-rich cassava root as the staple food. Goitre is treated according to the cause. If the thyroid gland is producing an excess of thyroid hormones (T3 and T4), radioactive iodine is given to the patient to shrink the gland. If goitre is caused by iodine deficiency, small doses of iodide in the form of Lugol's iodine or KI solution are given. If the goitre is associated with
Trace field of a representation of formula_4 (see for example in ). The "invariant trace field" is equal to the trace field of the subgroup formula_7 generated by all squares of elements of formula_4 (a finite-index subgroup of formula_4). The invariant trace field of Fuchsian groups is stable under taking commensurable groups. This is not the case for the trace field; in particular the trace field is in general different from the invariant trace field. Let formula_4 be a Fuchsian group and formula_11 its trace field. Let formula_12 be the formula_11-subalgebra of the matrix algebra formula_14 generated by the preimages of elements of formula_4. The