Radioactive Iodine use for thyroid problems

Written by: Matan Feldman, 203723606
Biological Introduction:
The thyroid gland is found in the neck, below the thyroid cartilage:
The thyroid gland controls how quickly the body uses energy, creates
proteins, and controls how sensitive the body is to hormones. It
participates in these processes s by producing thyroid hormones, mainly
triiodothyronine (T 3 ) and thyroxine (T 4 ) – both are synthesized from
iodine (and tyrosine). The thyroid is composed of spherical follicles that
selectively absorb iodine (such as I - ions) from the blood for production
of thyroid hormones, but also for storage of iodine in thyroglobulin. In
fact, iodine is necessary for other important iodine-concentrating
organs
as breast, stomach and more. 25% of all the body's iodide ions are in the
thyroid gland.
There are 3 common disorders related to the thyroid gland:
* Hyperthyroidism - the clinical condition of increased thyroid hormones
in the blood.
* Hypothyroidism - a condition in which the thyroid gland does not make
enough thyroid hormones.

* Thyroid nodules: generally benign thyroid neoplasms, but may also be
thyroid cancers. There most common types of thyroid cancers are
papillary carcinoma and follicular carcinoma.
The treatment with RAI (Radioactive Iodine):
The RAI treatment is based on the fact that the thyroid accumulates
iodine and uses it in order to produce the mentioned hormones, which are
required for normal body function. This RAI is just like the iodine found
in foods such as fish and iodized salt, except that it releases an electron,
or beta particle, which creates its therapeutic action.
There are two radioactive isotopes which are commonly used in patients
with thyroid disorders: s: I-123, which is harmless to thyroid cells, and I-
131, which destroys thyroid cells.
The radiation emitted by each of them can be detected from outside the
patient's body in order to gain information about thyroid function and
take pictures of the size and location of thyroid tissues. The RAI is given
to the patients by mouth in pill or in liquid form.
Usually, the harmless to thyroid cells I-123 is used to take pictures and
determine the activity of the intact thyroid gland (Thyroid Scan and
Radioactive Iodine Uptake - RAIU). One benefit of the use of I-123 is the
fact that there are no special radiation precautions necessary after a
thyroid scan or RAIU.

I-131 can also be used to take pictures of the thyroid gland, although it is
rarely used due to its harmful effects on thyroid cells.
The hyperthyroidism disease used to be treated by the use of Beta
Blockers drugs, but due to the side-effects of these drugs, and the
problematic use of drugs in many countries, some patients prefer the RAI
iodine-131 treatment. RAI is used in order to destroy a part of the thyroid
gland or the whole gland, since the radioactive iodine is selectively taken
up by the gland and gradually destroys the cells of the gland. The RAI
treatment may take up to several months to have its effect, beginning
about two weeks after the treatment.
Alternatively, the gland may be partially or entirely removed surgically,
but iodine treatment is usually preferred by patients, because the surgery
is invasive and also risks the nerves controlling the vocal cords and the
parathyroid. If the entire thyroid gland is removed, another thyroid
disease appears – Hypothyroidism, which is treated by thyroid hormone
replacement.
The I-131 RAI is also given in order to shrink thyroid glands that are
functioning normally but are causing problems because of their size, as
with the Goiter brochure.
Large doses of I-131 are used to destroy thyroid cancer cells.
Radiation safety precautions after the RAI treatment:
Although the treatments with 131-I are generally safe, it's obvious that
RAI produces some radiation. Therefore, patients must do their best to
avoid radiation exposure to others, particularly to pregnant women and
young children. Patients may have to stay isolated in the hospital for
about 24 hours to avoid exposing the radiation to others. The amount of
radiation exposure markedly decreases as the distance from the patient
increases.
Patients who need to travel in the days after I-131 RAI treatment are
carrying a letter of explanation from their physician, because radiation
detection devices used at airports or in federal buildings could identify
the smallest radiation levels.

The relevant section of the course is (obviously) Nuclear
Physics, Radio activeness.
Sources:
Wikipedia –
* http://en.wikipedia.org/wiki/Thyroid
* http://en.wikipedia.org/wiki/Hyperthyroidism
* http://en.wikipedia.org/wiki/Thyroid_neoplasm
Hadassah institute's website -
* http://www.hadassah.org.il/NR/rdonlyres/4420F310-F6CE-4F5F-
B1D2-
755A25A1052E/3012/%D7%97%D7%95%D7%91%D7%A8%D7%AA
%D7%9E%D7%99%D7%93%D7%A2%D7%99%D7%95%D7%93%D7
%A8%D7%93%D7%99%D7%95%D7%90%D7%A7%D7%98%D7%99
%D7%91%D7%9914105.pdf
American Thyroid Association's website –
*
http://www.thyroid.org/patients/patient_brochures/radioactive_iodine.htm
l
Others –
* http://www.abiliko.co.il/index2.php?id=1157&lang=HEB
* http://www.endocrinologist.com/Radioactive.html
* http://www.endonurses.org/toolbox/pdf/patient_education/ATA%20RadioactiveIRAI.pdf