Which patients need radioiodine therapy?

The presence of goiter in some cases suggests treatment with radioactive iodine. Radioiodine therapy is one of the effective, safe and relatively affordable methods of treating various forms of thyroid goiter. Radioiodine therapy uses the isotope ¹³¹ I, which belongs to mixed emitters. This isotope goes through the same path of metabolic changes as the stable iodine isotope ¹²⁷ I. Its half-life is 193 hours, which is equivalent to 8 days. Excreted from the body by the kidneys and endocrine glands.

Impact of radioiodine therapy on the course of thyroid cancer

Radiotherapy is carried out for a specific purpose and gives results in thyroid pathologies. How does radioiodine therapy affect the course of thyroid cancer?

Goals and objectives of radioiodine therapy:

Reduce thyroid cancer mortality and recurrence rates.
Affect existing thyroid cancer metastases.
Destroy thyroid tissue and probable tumor foci, if there is no possibility to remove them surgically.
Destroy gland tissue that is overfunctioning and causing thyrotoxicosis. This is how a stable hypothyroid state is achieved.
Improve the quality of diagnosing the presence of tumor recurrence and metastases of thyroid cancer.

Thus, in thyroid cancer, radioiodine therapy is given to improve the patient's prognosis.

Indications and contraindications for radioiodine therapy

There are indications and contraindications for any procedure. So radioiodine therapy is indicated only for certain conditions of the thyroid gland:

Presence of thyroid cancer metastases after thyroidectomy.
Diffuse toxic goiter (Graves-Basedow's disease).
The state of functional autonomy of the thyroid gland.
Presence of distant metastases.
Negative dynamics of thyroglobulin concentration in blood plasma after removal of the gland due to cancer.
Stage N 1b

Contraindications to radioiodine therapy are absolute and general. The absolute ones include pregnancy and lactation, the general ones include acute mental conditions, pulmonary tuberculosis, acute peptic ulcer, hypo- and aplastic anemia, diseases of the liver and kidneys, which are accompanied by violations of their functions.

Requirements before radioiodine therapy. Preparing for the procedure

Before starting radioiodine therapy, it is necessary to eliminate the symptoms of thyrotoxicosis and achieve normal T3 and T4 values. Preliminary therapy with thyreostatics is necessary, since the release of previously synthesized hormones into the blood can provoke the development of radiation thyroiditis and aggravate the symptoms of thyrotoxicosis. But 8-10 days before radioiodine therapy, it is necessary to stop taking thyreostatics in order not to prevent the penetration of ¹³¹I into the thyroid gland, and in order for radioiodine therapy to be effective.

The exception is the subclinical course of thyrotoxicosis. Before radioiodine therapy, the patient is strongly advised to exclude from the diet any foods that contain iodine, as well as taking medications with iodine. Find out if the patient has taken amiodarone.

If there is any doubt about the intake of iodine, or the patient has performed diagnostic studies with the preliminary administration of iodine-containing contrast agents, then it is necessary to find out the concentration of iodine in the urine. If the iodine content in the urine is more than 100 mcg/l, the procedure of radioiodine therapy should be postponed for 2-3 months.

Do I need to stop taking thyroid hormones before radioiodine therapy?

In thyroid cancer, thyroidectomy is a prerequisite before radioiodine therapy, since iodine in the presence of gland tissue will be captured by it, and not by metastases. After thyroidectomy, the procedure is carried out 3-4 weeks after it, but before the appointment of thyroid hormones.

A very important condition for radioiodine therapy is the stimulation of absorption of ¹³¹ I by the administration of thyroid-stimulating hormone.

If the patient is taking thyroid hormone preparations, then levothyroxine sodium should be discontinued 4-5 weeks in advance and liothyronine should be discontinued 2 weeks in advance.

To alleviate the patient's condition and reduce hypothyroidism, liothyronine is prescribed at a dose of 50 mcg per day for 3 weeks. His appointment is canceled 2 weeks before radioiodine therapy.

Recombinant human TSH is administered to the patient for the purpose of exogenous stimulation of TSH production. This makes it possible to prevent a decrease in the quality of life after the abolition of levothyroxine. The introduction of human TSH is carried out in the muscle at a dose of 0.9 mg for 2 days. Radioiodine therapy is carried out one day after the second injection.

The level of TSH in the blood serum must be measured before prescribing I, and it must be greater than the established parameters (more than 30mED/l).

How and where is radioiodine therapy performed? Stages of events

The method of conducting radioiodine therapy includes the following activities:

Preliminary examination of the patient.
Carrying out radionuclide diagnostics with the introduction of a radiopharmaceutical intravenously.
Preparation of the radiopharmaceutical.
Performing radioiodine therapy with oral administration of a radiopharmaceutical.
Dosimetric planning of iodine therapy, monitoring of actual radiation doses during radioiodine therapy, radiation monitoring of patients, personnel and premises.

Radioiodine therapy is carried out only in centers specialized for this purpose, which are able to ensure the environmental and radiation safety of patients, employees and the environment.