Iodine
Toxicity (UL)
1,100 micrograms
Examples of goitrogens
Cassava, raw veggies in excess (cabbage, broccoli, brussel sprouts) and lithium
Cretinism is either...
- Neurological (irreversible) - Hypothyroid (reversible)
Iodine is a halogen so...
- its a nonmetal - typically found as Iodide (I-)
Assessing iodine techniques:
-Urinary iodine excretion -Thyroid size -Serum TSH concentrations
5-30% of iodine deficiency is
brain damage
Iodide deficiency effects depend on age of exposure. So, the embryo/fetus has profound effects. Infants and children:
failure to grow normally and develop intellectually
Very efficient absorption results in..
few low fecal iodide content
Thyroid hormone has its receptors in the nucleus so it is largely influenced by
gene expression
Thyroid hormone promotes activites associated with ______ which increases metabolism and heat production
glucose breakdown
Deficiency of iodine results in
goiter
When iodine deficiency occurs in children and adults, the thyroid gland grows and becomes enlarged, producing ___ a classic sign of iodine deficiency
goiter
An adult contains roughly ______ milligrams of iodide
15-20
RDA
150 micrograms (1/4 teaspoon of salt is 70 micrograms)
Cretinism
3rd trimester, stunted growth and mental development. Large heads, deaf (mostly in developing countries)
The thyroid gland contains roughly _____ of body iodide
75-80%
Overall absorption is greater than
90%
What is needed in iodine
Active transport
Compounds that inhibit iodine uptake by the thyroid gland are found in which of the following foods?
Cruciferous vegetables (cabbage like) raw
Iodine deficiency and iodine deficiency disorders (IDD)
Goiter, cretinism (neurological and hypothyroid)
Which compounds inhibit iodine uptake by the thyroid gland?
Goitrogens
#1 consequence of iodine deficiency
Increased risk of fetal and infant mortality
What may happen when theres goitrogens?
Interferes with thyroid hormone production May impair uptake of ioide into thyroid gland May affect hormone production or release
Thyroglobin
STORAGE FORM OF IODINE in which idioine in the thyroid gland is incorporated into this protein
Goitrogens
Substances that interfere with iodine metabolism that leads to a goiter
Almost all of the tyroxine (T4) in the circulation may become converted to ____ after entering peripheral tissue
T3
So which is more metabolically active?
T3
THriodothyronine is
T3
What are referred to as the thyroid hormone?
T3 and T4
Thyroxine is
T4
Roughly 90% of thyroid hormone released daily is:
T4 - this is PREDOMINATING IN THE BLOOD
T3 and T4 bund to
TBP
Thyroid gland:
TSH stimulates the thyroid gland to take up iodine and produce thyroid hormones (T3 and T4)
Iodine functions and mechanisms of action:
Thyroid hormone synthesis Transport of thyroid hormones in the blood
Hypothyroid can occur...
later in pregnancy and symptoms are sleepy, slow development
Today, thyroid hormone is prescribed to treat hypothroidism,
a condition in which the thyroid gland fails to produce adequate thyroid hormone
30-70% of iodine deficiency comes is
loss energy due to hypothyroidism
Brain:
low in blood iodine concentration
Iodide deficiency has been eradicated for most part from many regions so, they did what?
added iodine to salt
Impaired selenium status...
affect thyroid hormone metabolism
If sadie wanted to avoid cruciferous veggies, she would avoid
cabbage, cauliflower, and brussel sprouts
_____ are more suspectible to iodine deficiency
children
When a baby experiences iodine deficiency in utero, ___ may result
cretinism
Neurological cretinism is due to a iodine deficiency in..
early pregnany that damages brain and nervous system. This can be mild to severee
Dans grandfather has a goiter. The goiter could be the result of
either a iodine deficiency or iodine toxicity!!!
In the muscle, iodine...
enhances contraction
In the adipose tissue, iodine...
enhances lipolysis
Thyroid hormone affects virtually...
every cell in the body (with the exception of the adult brain, testes, spleen, uterus and thyroid gland itself)
Iodine deficiency results in all of the following except
excessive growth in stature
Iron and vitamin A deficiencies may..
magnify effects
goiter
hypertrophy of the thyroid gland
Approximately 90% of iodine is excreted..
in the urine within 1 or 2 days
in the cardiovascular system, iodine...
increases heart rate
Pituitary gland:
increases release of thyroid stimulating hormone (TSH)
Low bloow levels of ___ stimulates the pituiary gland to increase release of TSH
iodine
Which trace mineral is an essential component of the hormones produced by the thyroid gland?
iodine
The best source of iodine in the american diet is
iodized salt
Other consequences of iodine deficiency
irreversible mental and neurological retardation, hypothroidism, goiter
Excessive iodide is primarily excreted by the
kidneys
Iodine excretion is in:
mostly urine, also feces (low) and sweat
The absorptioj of iodine occurs efficiently along the length of the intestinal tract, including the stomach. This results in..
nearly complete absorption of iodide, like sodium, potassium and chloride
Thyroid hormone output thus increases and exerts...
negative feedback on the release of TRH
HOWEVER, T3 is 5 to 10 times more ___ than T4
potent (stronger)
Now, there is a worry that the US is using too much iodized salt in..
preparation, manufacturing and seasoning
Iodine deficiency is the greatest single cause of..
preventable brain damage and mental retardation in the world today (AFRICA)
At least 60 micrograms of iodide must be taken up by the thyroid gland daily in order to..
produce adequate thyroid hormone
in the bone, iodine...
promotes anabolism (growth and development)
Dairy foods are a fair source but it...
reflects what the cows feed or the soil of its grazing region was
Other sources:
salt, haddock, cottage cheese, shrimp, egg, cheddar cheese, ground beef
Main 2 sources:
seafood, iodized salt. 1/4 teaspoon provides 70 micrograms of iodide
Treatment of the goiter can..
shrink it but not necessarily correct any of the developmental problems in children
Food content variable based on..
soil concentration and water source
In metabolism, iodine..
stimulates metabolic rate and cellular oxygen consumption in metabolically active tissue
In the gastrointesinal tract, iodine...
stimulates nutrient digestion and absorption
The hypothalamus releases the peptide thyrotropin-releasing hormone which...
stimulates the pituiary to produce thyroid stimulating hormone or thyrotropin
Community assessment
testing people in areas suspected of deficiency, physical exams, hormone levels, urine samples
Iodide appears to dissolved freely into
the blood
Toxicity is possible and may cause problems with the..
thyroid gland
For the most part, iodide is concentrated in the
thyroid glands as well as the salivary gland and gastric glands
TSH circulates to the thyroid gland which initiates production of...
thyroid hormone which then enters the blood and circulates to peripheral tissue
Iodine is an essential component of the..
thyroid hormones
Iodine uptake by the thyroid is regulated by
thyroid-stimulating hormone
Transport of thyroid hormones in the blood include:
thyroxine-binding globulin, albumin and transthyretin
Approximately 80% of thyroid hormone binds to
thyroxine-binding protein (TBP)
Methods of checking deficiency:
urine excretion, checking for the size of the thyroid gland, checking TSH level and serum thyroglobulin