Iodine
The essential trace element that forms the backbone of thyroid hormone — T4 and T3 are literally named for how many iodine atoms they carry.
Both deficiency and excess cause thyroid dysfunction, and the window is narrower than people assume. Deficiency is re-emerging with reduced iodized salt use and plant-based diets.
Optimal ranges, root causes, and the complete correction protocol — nutrition, supplements, lifestyle, hormones and peptides — plus 100+ other markers.
Unlock everything — $10/mo →📚 WHO/UNICEF/ICCIDD iodine status assessment. American Thyroid Association statement on iodine supplementation.
🩸 Test your Iodine
Order directly through Marek Diagnostics — no doctor's visit needed, drawn at any Quest location in the US. Code CAMERON applies 10% off automatically.
Order this test — 10% off → Browse all 102 markers →What Iodine is usually tested alongside
On its own, one marker is a data point. These panels include Iodine plus the markers that make it interpretable — each names every test, why it is on the list, and loads the whole set into your cart in one click at 10% off.
includes this + 8 more markers — Vegan, vegetarian, or mostly plant-based — whether you've been doing it a decade or three months.
includes this + 10 more markers — Restrictive diet, plant-based, post-bariatric, on a GLP-1, heavy training load, or you just want to stop guessing which supplements you actually need.
What moves your Iodine
1 supplement in the Vault have a documented effect on this marker, or are a reason to have measured it first:
Browse all 237 compounds & 350 supplements →
Would you feel it? Symptoms Iodine helps explain
People rarely search for a marker — they search for how they feel. These are the complaints where this marker is worth checking, and whether it is a first-line test or a follow-up once the obvious causes are ruled out.
Why your Iodine might be wrong
Most abnormal results are interference, not disease. These are the things that measurably move this specific marker — check them before you change anything. Each one says whether the number is wrong and should be repeated, badly timed and should be redrawn, or real with a cause worth explaining.
Spot urinary iodine reflects the last day or so and varies hugely with single foods. Seaweed, dairy or an iodine-containing supplement will dominate the result.
Spot iodine describes populations well and individuals poorly. Repeat over several days if it matters.
CT contrast delivers an enormous iodine load that distorts results and thyroid function for weeks to months.
Note any recent scan with contrast.
What Iodine means in combination
A single marker tells you a little. Combinations tell you the story — these are the named patterns this marker takes part in, and what each one points at.
That is a malabsorption pattern, not a diet pattern. Coeliac disease, atrophic gastritis, H. pylori, pancreatic insufficiency and inflammatory bowel disease all present this way, and correcting the individual nutrients without finding the cause is a treadmill.
Investigate why absorption is failing rather than supplementing indefinitely. Coeliac serology must be done before removing gluten. Any neurological symptom with low B12 or copper needs urgent attention.
The thyroid compensates for a long time before TSH moves, so adequate TSH does not confirm adequate iodine. It matters most in pregnancy, where requirements rise sharply and deficiency affects fetal neurodevelopment.
Correct with a modest dose — a prenatal covers it. Excess iodine is also harmful and precipitates dysfunction in autoimmune thyroid disease, so check thyroid antibodies before supplementing. And a spot urinary iodine reflects the last day, not your status.
What to test next
Markers rarely answer alone. These are the ones that put Iodine in context — each with its own full breakdown.
Frequently asked questions
Serum 40–92 µg/L; urinary iodine is the better population measure Ranges vary by laboratory and assay — always compare to the range printed on your own report.
Optimal ranges, root causes and the full correction protocol are available inside Coach Cam's Peptide Academy.
See the full breakdown inside the Academy.
See the full breakdown inside the Academy.
You can order Iodine directly through Marek Diagnostics without a doctor's visit — drawn at any Quest Diagnostics location in the US. Code CAMERON applies 10% off automatically.