Měření jódu
Distribuce
- Jodid rychle absorbován a distribuován v ECT, slinách, mléku, žaludku a mléčné žláze
Distribuční prostor
- Asi 25 litrů (asi 25 % tělesné hmotnosti)
Intestinální absorption
- Ingested iodine is considered to be high (> 90 %) [1]
- Jodidový / jodátový iont v žaludku na jodid (Ganong, 2005)
Dermal iodine:
- Only very small quantities of iodine are absorbed through an intact skin
- Iodine can be absorbed by wounds and abrasions.
- Enhanced absorption occurs through
- Denuded skin, decubitus ulcers,
- Mucosal surfaces with high absorptive capacity (vagina)
- Large areas of intact skin [10]
Vylučování jódu
- Hlavně ledviny
- Steady state, the urinary iodine (UI) excretion represents more than 90 % of the dietary intake
- Therefore a good indicator of recent iodine intakes
- UI concentration has also been used to define the iodine status of a population. [1]
- Vylučují do moči 80-90 % přijatého jódu (Ganong, 2005)
- Stolicí, potem a dechem
- Mnohem méně jódu než ledvinami (Zamrazil, 1999)
Do mléka
- Quarter of the iodine taken by the mother can be secreted in the milk within 24 hours.
- Potassium iodate
- Can partially block transport of radioiodine in the milk.
- The same criteria should apply when selecting a dose of potassium iodate to protect a lactating mother
- As that used for other young adults under 40 years of age
- [ www.medicines.org.uk/emc/medicine/5234#gref ]
Oral: Iodine
- Appears to be inactivated by combination with gastrointestinal contents.
- Absorption is poor due to rapid conversion of iodine to iodide
- Absorbed iodine is rapidly converted to iodide and is stored in the thyroid as thyroglobulin [10]
Metabolism of Iodine
- Is an easily oxidizable substance
- Food that is present in the digestive tract, will oxidize iodine to iodide
- Which is not corrosive to the gastrointestinal tract [10]
Normální plazmatická hladina jódu
- Cca 0,3 mcg/100 ml
Sledování metabolismu jódu
- Značený jód 131 I a 125 I ve stopových dávkách
Využití jódu k syntéze hormonů a skladování v tyreoglobulinu
- Asi 75 mcg jodidu denně
Thyroglobulin
- Useful biomarkers of iodine status
- Depending on age and population group and their iodine status [6]
Thyroid hormone T4 (thyroxine or 3,5,3,5-tetraiodothyronine)
- Useful biomarkers of iodine status
- Depending on age and population group and their iodine status [6]
Thyroid-stimulating hormone in serum
- Useful biomarkers of iodine status
- Depending on age and population group and their iodine status [6]
Ukazatel příjmu jódu
- Jodurie
Vstup jódu do štítné žlázy
- Denně asi 115 mcg jodidu
Renal clearance of iodide/iodate
- Is usually in the range of 30 to 50 ml of serum/minute
- Is closely related to glomerular filtration
- Is little affected by the iodate load
- Most radioiodine not taken up by the thyroid gland after a single oral bolus of iodate
- Is excreted in the urine over the subsequent 48-hour period.
- [ www.medicines.org.uk/emc/medicine/5234#gref ]
