Iodine
Iodine is an essential mineral of the body which helps in the
production of thyroid hormone in the thyroid gland. Deficiency of
iodine may produce hypothyroidism and goitre. Iodine salts are
used for various other purposes like investigatory works and in
therapeutics.
iodine has many extrathyroidal benefits
Iodine as an antioxidant
β’ Clinical trials indicate that iodine functions as an antioxidant, specific scavenger of hydroxyl radicals and increases the antioxidant status of human serum. Also, it binds to polyunsaturated fatty acids and renders them less susceptible to free radicals.
Apoptosis and cancer
β’ Clinical trials that evaluated the role of iodine in apoptosis and its anticancer effect, found that iodine induces apoptosis in lung cancer and breast cancer cells.
β’ Epidemiological studies have shown that high intake of iodine is associated with low incidence of breast cancer, and low intake with high incidence of breast cancer.
Other functions of inorganic iodine
β’ Clinical trials analyzing the effect of iodine on immune
system observed that iodine suppresses
autoimmunity, strengthens T-cell adaptive immune
system, and protects against abnormal growth of
bacteria in the stomach, especially H. pylori.
Fibrocystic breast disease
β’ Clinical trials evaluated the effect of iodine on fibrocystic disease of the breast, of which one study reported that iodine supplement could successfully treat 70% of patients with fibrocystic breast disease. Other studies reported that iodine affects fibrocystic diseases progression.
Summary
Iodine is found to be essential, not only in functioning of thyroid gland but also has other beneficial effects such as:
β’ Antioxidant activity
β’ Anticancerandapoptosis
β’ Improves immune system
β’ Successfully treats fibrocystic breast disease
There are various radio-isotopes of iodine which are used in
medicine for various purposes.
WARNINGS:
Iodine should not be used by people allergic to iodine. Keep out
of the reach of children. In case of overdose or allergic
reaction, contact a physician or the public health authority.
ADVERSE REACTIONS:
Side Effects
Usually, side effects of iodine happen when people take higher
doses for a long time. You should be careful not to take more
than the recommended dose or take it for longer than you are
told. Side effects are unlikely because of the low dose and the
short time you will be taking the drug.
Possible side effects include skin rashes, swelling of the
salivary glands, and "iodism" (metallic taste, burning mouth and
throat, sore teeth and gums, symptoms of a head cold, and
sometimes stomach upset and diarrhea).
A few people have an allergic reaction with more serious
symptoms. These could be fever and joint pains, or swelling of
parts of the face and body and at times severe shortness of
breath requiring immediate medical attention.
Taking iodide may rarely cause over activity of the thyroid
gland, under activity of the thyroid gland, or enlargement of the
thyroid gland (goiter).
What to Do if Side Effects Occur
If the side effects are severe or if you have an allergic
reaction, stop taking potassium iodide. Then, if possible, call a
doctor or public health authority for instructions.
Iodine-123
HALF-LIFE. 13.2 hrs.
Iodine-123 has similar adverse effects and precautions to
Those of iodine-131 (see below).
Its principal use is in thyroid uptake tests and thyroid imaging
when it is given by mouth or intravenous injection as sodium
iodide.
Sodium iodohippurate is employed intravenously in
tests of renal function and in renal imaging.
Iobenguane (m-iodobenzylguanidine )is given in-
travenously for the localisation of certain tumours, for exam-
ple phaeochromocytomas. and for the evaluation of
neuroblastoma. It is also used for functional studies of the ad-
renal medulla and myocardium.
Various monoclonal antibodies have been labelled with io-
dine-123; potential applications include the detection of ma-
lignant neoplasms.
Iodine-125
HALF-LIFE. 60.1 days.
Iodine-125 has similar adverse effects and precautions to
those of iodine-131 (see below).
Iodine-125 is not very suitable for the external counting of
radioactivity in the thyroid gland because its y-energy is weak
and tissue absorption is high. However, it is very suitable for
radioimmunoassays in vitro and because it has a long half-life
it is preferred as a label for many compounds to detect and
estimate drugs and hormones in body fluids.
Iodine-125 may be used orally as sodium iodide , in the
diagnosis of thyroid disorders.
Sodium iothalamate has been used intravenously in the
determination of glomerular filtration rate and sodium iodo-
hippurate , intravenously for the measurement of effec-
tive renal plasma flow.
Iodine-125. as iodinated human fibrinogen, has been
used intravenously to demonstrate and locate deep vein
thrombosis of the leg. Iodinated fibrinogen has also
been used in the measurement of fibrinogen metabolism in
certain disturbances of blood coagulation.
Iodinated albumin has been used for the determination
of blood or plasma volume.
IODINE-131
A small percentage of patients treated with iodine-131 for
thyrotoxicosis become hypothyroid each year and eventually most
patient will require thyroid replacement therapy.
Hypoparathyroidism has also been reported. Radiation thyroiditis
with soreness may shortly develop after treatment. There may be
severe and potentially dangerous swelling of the thyroid
especially in patients with large goitres and this has on rare
occasions produced asphyxiation. Leukaemia and carcinoma of the
thyroid have occasionally been reported, particularly in young
patients. However retrospective studies have
shown no increased incidence in adults after iodine-131 treat-
ment for thyrotoxicosis.
In the treatment of thyroid carcinoma, the larger doses of
radioactive iodine sometimes cause nausea and vomiting a
few days after ingestion, which may be due to gastritis as
iodine-131 is also concentrated in gastric mucosa. Large
doses depress the bone marrow.
Precautions
The use of sodium iodide is contra-indicated, even in
diagnostic doses, during pregnancy and lactation. Sodium io-
dide should not bt given to patients with large toxic
nodular goitres or to patients with severe thyrotoxic heart dis-
ease. There is some controversy as to whether radio-iodine
therapy exacerbates Graves' ophthalmopathy .
Many drugs have been reported to interfere with thyroid- or
other organ-function studies and checks should be made on
any treatment the patient might be receiving before any esti-
mations are carried out.
Uses and Administration
Iodine radioisotopes are mainly used in studies of thyroid
function and in the treatment of hyperthyroidism
and some forms of thyroid carcinoma.
Iodine radioisotopes can be incorporated into many com-
pounds including liothyronine and thyroxine, triglycerides
and fatty acids, such as triolein and oleic acid, and proteins,
such as iodinated human albumin, with varying degrees of
stability and with little or no change in the biological activity
of the labelled molecule. It is common practice to saturate the
thyroid with non-radioactive iodine when uptake of radiation
by the gland is not desired (see Radiation Protection, p. 1494).
Sodium iodide is given by mouth and by intravenous
injection in studies of thyroid function, particularly in meas-
urements of the uptake of iodine by the thyroid, and in thyroid
scanning. It is also used in the treatment of hyperthyroidism
and in the treatment of malignant neoplasm of the thyroid.
Injections containing iobenguane (m-iodobenzylguani-
dine) may be employed for the localisation and treat-
ment of pheochromocytoma and neuroblastoma.
Human albumin iodinated with iodine-131 is employed in the
determination of the blood or plasma volume.
Sodium iodohippurate is used intravenously for renal
function tests and for renal imaging.
Rose bengal sodium has been given intravenously in
tests of liver function.
Iodinated norcholesterol (6p-iodomethyl-19-norc-
holest-5(10)-en-3p-ol has been used for adrenal scin-
tigraphy by slow intravenous injection.
Various monoclonal antibodies labelled with iodine-131 are
used for the detection of malignant neoplasms and some are
being investigated for therapeutic purposes.
Iodine-131
Half life. 8.04 days.
Adverse Effects
A small percentage of patients treated with iodine-131 for
thyrotoxicosis become hypothyroid each year and eventually
most patients will require thyroid replacement therapy. Hy-
poparathyroidism has also been reported. Radiation thyroidi-
tis with soreness may develop shortly after treatment. There
may be severe and potentially dangerous swelling of the thy-
roid especially in patients with large goitres and this has on
rare occasions produced asphyxiation. Leukaemia and carci-
noma of the thyroid have occasionally been reported, partic-