Final: Iodine (I) Flashcards
(25 cards)
What is the function of iodine?
Synthesis of thyroid hormones thyroxine and triiodothyronine (regulate energy metabolism)
When is thyroid production increased?
During cold weather
When is thyroid hormone levels the highest (body-wise)?
In lactation and growth
What 3 processes does production of thyroid hormone involve?
- Active transport of iodide from plasma across thyroid cell mem. (inhibited by cyanogenic goitrogens)
- Synthesis of thyroid hormones (inhibited by cruceiferous goitrogens)
- Secretion of thyroid hormones
How much iodine is absorbed and where does unabsorbed iodine go?
80-90%; excreted in urine and milk
What happens to milk iodine content when dietary iodine content increases?
it also increases
What are diet sources of iodine?
Forage and grains (depend on soil)
Seafood = high
Thyroid glands
What happens as a result of iodine deficiency?
Reduction in thyroid hormone production
Enlargement of the thyroid = goiter
What signs can iodine-deficient newborns show?
Hairless, weak, or dead
What signs does a mother show that gives birth to an iodine-deficient animal?
Shows no signs; took up all iodine from circulation, leaving the fetus deficient
What is hyperthyroidism in cats blamed on?
High iodine content of cat food due to thyroid glands being in rendered meat and bone meal
What are inorganic sources of iodine?
Iodides of Na, K, and Ca
(K iodide is easily oxidized and volatilizes before the animal can ingest it)
Salt licks
What is goiter?
Lack of thyroxine that stimulates the pituitary gland to make TSH –> enlargement of thyroid
What are goitrogens?
Compounds that interfere with synthesis or secretion of thyroid hormones
What are the 2 types of goitrogens?
- Cyanogenic goitrogens
2. Progoitrins/Goitrins
What do cyanogenic goitrogens do and what are some examples?
Impair iodide uptake by thyroid gland.
Soybeans, beet pulp, corn, sweet potato, white clover, millet
What can be done to overcome cyanogenic goitrogens?
Increasing supplemental iodine
Whatdo progoitrins/goitrins do and what are some examples?
Inhibit thyroperoxidase
Rape, kale, cabbage, turnips, mustard, onions
What can be done to overcome progoitrins/goitrins?
Offending feedstuff needs to be reduced or removed from diet (cannot supplement with iodine)
How does foot rot relate to iodine deficiency?
High iodine levels will prevent bacteria from occurring thus preventing foot rot
What does excess iodine do to ruminants?
Depression Salivation Oculonasal discharge Tachycardia Hyperthermia Circulatory collapse Abortion
What effect does iodinated casein have on cows?
Feed addtive with iodine attached to tyrosine residues of casein = boost milk production
- Works for 2-3 weeks, then cow dies
What is Frank’s iodide?
Old IV tx for “lumpy jaw”
What is a diet treatment for hyperthryroid cats?
Hill’s y/d diet
