Jod (Urin): the pathway in the body

Jod (Urin) is part of the pathway “Iodine”. This page shows the whole pathway; the station of Jod (Urin) is highlighted.

Where this laboratory value sits: Iodine in food — mostly as iodide. In food, iodine occurs mainly as iodide, for example in sea fish, seaweed, milk and iodised table salt. Source 1

In brief

Iodine is a trace element that mostly enters the body as iodide in food and is largely excreted in urine. The thyroid gland builds it into its hormones thyroxine (T4) and triiodothyronine (T3).

9 stations · 6 sources

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The pathway step by step

Iodine in food → Iodide in blood In the small intestine, iodide passes almost completely into the blood and spreads through the body water. From there, the thyroid and some other tissues absorb it. Source 1, 2
Iodide in blood → Iodide in urine The kidneys excrete most of the absorbed iodide in the urine. The amount in urine therefore mainly reflects intake over the last few days. Source 1
Iodide in the cell → Iodide in the follicle Pendrin On the opposite side of the cell, the transporter pendrin releases iodide into the follicle space. This is where the thyroid stores the protein thyroglobulin. Source 3
Iodide in the follicle → MIT and DIT TPO · Hydrogen peroxide, Haem (iron) Thyroid peroxidase (TPO) links iodine to tyrosine units of thyroglobulin, forming mono- and diiodotyrosine. For this, the enzyme needs hydrogen peroxide, supplied by DUOX2. Source 3, 4
MIT and DIT → T4 and T3 TPO The same TPO couples two iodinated units together. This forms thyroxine (T4) and, in smaller amounts, triiodothyronine (T3) – both still attached to the carrier protein. Source 3
T4 and T3 → T4 in blood Proteases The cell reabsorbs thyroglobulin. Proteases in the lysosome cut the hormones out, and the cell releases them into the blood; iodide from the remaining units is reused. Source 3
T4 in blood → T3 in the target cell Deiodinases · Selenium In the tissues, deiodinases remove one iodine atom from T4; this produces T3, which binds to the thyroid hormone receptor. These enzymes carry selenium in their active site. Source 5, 4

Cofactors in this pathway

Selenium — Component of the deiodinases, which convert T4 to T3 in the tissues Source 4, 5In the ORY catalogue as a laboratory value: Selen
Iron — Haem iron in the active site of thyroid peroxidase (TPO) Source 4, 3In the ORY catalogue as a laboratory value: Eisen
Tyrosine — Building block of thyroglobulin to which TPO attaches the iodine Source 3In the ORY catalogue as a laboratory value: Tyrosin
Sodium — Its gradient drives the sodium-iodide symporter (NIS) Source 2In the ORY catalogue as a laboratory value: Natrium (intrazellulär)
NADPH — Electron donor of DUOX2, which forms hydrogen peroxide for TPO Source 3

Sources

Zimmermann MB, Andersson M. Assessment of iodine nutrition in populations: past, present, and future. Nutr Rev 2012 · PubMed 23035804
Portulano C, Paroder-Belenitsky M, Carrasco N. The Na+/I- symporter (NIS): mechanism and medical impact. Endocr Rev 2014 · PubMed 24311738
Carvalho DP, Dupuy C. Thyroid hormone biosynthesis and release. Mol Cell Endocrinol 2017 · PubMed 28153798
Köhrle J. Selenium, Iodine and Iron-Essential Trace Elements for Thyroid Hormone Synthesis and Metabolism. Int J Mol Sci 2023 · PubMed 36834802
Gereben B, Zeöld A, Dentice M et al. Activation and inactivation of thyroid hormone by deiodinases: local action with general consequences. Cell Mol Life Sci 2008 · PubMed 17989921
Serrano-Nascimento C, Nunes MT. Perchlorate, nitrate, and thiocyanate: Environmental relevant NIS-inhibitors pollutants and their impact on thyroid function and human health. Front Endocrinol (Lausanne) 2022 · PubMed 36339434

Whole pathway: Iodine

Related pathways

Thyroid hormones — iodide in the cell
Vitamin C — Selen, Eisen
8-OHdG — Selen, Eisen
Borrelia — Selen, Eisen
IgG antibodies to food — Selen, Eisen

As of 2026-09-16. Draft written by Claude to schema v2; sources checked in PubMed; expert review pending
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