Fields of application of iodide preparations
If the formation of an enlargement of the thyroid gland is to be prevented, a daily intake of 100 μg or also 200 μg iodide is sufficient. If enlargement is already present, 200 μg to 400 μg are taken daily to reduce the size of the thyroid gland. In contrast to children, it has been shown, especially in adolescents and adults with iodine-deficient goiter, that a combination therapy with iodide and thyroid hormones is beneficial in contrast to a pure therapy with iodide.
It was found that a dosage of thyroid hormone (levothyroxine) and iodide in a ratio of 1:2 (for example, 75 μg levothyroxine plus 150 μg iodide) is most effective in reducing thyroid enlargement. In addition to iodide preparations that must be taken daily, there are also preparations that are dosed in such a way that once a week is sufficient.These products are especially suitable for people who cannot guarantee a daily intake or for people with an increased iodine requirement. If iodide is taken preventively, therapy is often necessary for years, often for a lifetime. If an enlargement of the thyroid gland already exists, a therapy over a period of two to four weeks is normally sufficient to reduce the enlargement of the thyroid gland in newborns. For children, adolescents and adults, a longer treatment of 6-12 months or even longer is required.
Contraindications
Iodide must not be used in cases of manifest hyperthyroidism. One speaks of manifest hyperthyroidism when the TSH level in the blood is suppressed, i.e. below the detection limit, and the concentration of the thyroid hormones themselves is increased. In the case of latent hyperthyroidism, i.e. when the TSH level is suppressed and the concentration of thyroid hormones is still normal, a dose of 150 μg iodide per day must not be exceeded.
A dosage of 300 – 1000 μg iodide per day should not be exceeded if a benign, hormone-forming tumor (autonomous adenoma) is present or if it is known that areas of the thyroid gland produce uncontrolled thyroid hormones. This does not apply to treatment before a planned operation. Treatment with iodide should also not be given in cases of inflammation of the vessels (urticaria vasculitis/hypocomplementary vasculitis) and dermatitis herpetiformis Duhring, a chronic inflammation of the skin.
In Hashimoto’s thyroiditis, an autoimmune disease of the thyroid gland, larger amounts of iodine can aggravate the disease or, if predisposed, lead to premature onset of the disease. Therefore, the intake of iodine should be avoided in existing Hashimoto’s thyroiditis. Even if close relatives suffer from this autoimmune disease, a differentiated approach is necessary.
However, the iodine content in the daily diet is no cause for concern. Another autoimmune disease of the thyroid gland is Graves’ disease, where an uncontrolled production of thyroid hormones occurs. Even in the presence of this autoimmune disease, excessive iodine intake should be avoided, as it can worsen the disease. Furthermore, hypersensitivity (allergy) to potassium iodide or another component of the preparation also rules out therapy with iodide.