TSH (Thyroid-Stimulating Hormone)
The pituitary's signal to the thyroid. It moves inversely to thyroid output — a high TSH means the body is shouting for more thyroid hormone.
The standard thyroid screen and a frequent explanation for stubborn fatigue, weight gain, cold intolerance, hair thinning, constipation and poor recovery. Thyroid disease is 5–8× more common in women.
The plan of attack
In this order. Most people start at step four, which is why they change five things at once and learn nothing.
- Confirm the number is real
Biotin (B7). Biotin interferes with the streptavidin-biotin immunoassays most hormone tests run on. Depending on the assay design it pushes the result falsely HIGH or falsely LOW — there is no single direction to correct for. Hair, skin and nail products are the usual source, and doses in those are far above the RDA. Stop biotin 48–72 hours before the draw, and check every supplement label rather than just the one labelled biotin. - Read it with its partner
Never interpret TSH alone. Order with Free T4, Free T3, and TPO antibodies — TSH can look normal while conversion is broken. Draw it alongside: Free T4 (Thyroxine), Free T3 (Triiodothyronine), Reverse T3. - Work out which direction is yours
If it's high — Hypothyroidism. High TSH with normal Free T4 = subclinical hypothyroidism.
If it's low — Hyperthyroidism or over-replacement — anxiety, palpitations, heat intolerance, muscle loss, bone loss. - Fix it in this order
Nutrition. Adequate iodine (seafood, dairy, iodized salt — but excess iodine can worsen autoimmune thyroid disease), selenium (2 Brazil nuts/day), zinc and iron. Avoid chronic severe caloric restriction, which suppresses thyroid output.
Lifestyle. Restore calories if dieting hard, manage stress (cortisol impairs conversion), sleep, and treat gut issues affecting absorption.
Supplements. Selenium has trial evidence for lowering TPO antibodies in Hashimoto's. Zinc and iron support T4→T3 conversion. Stop biotin 48–72h before any thyroid draw — it causes badly false results.
Hormones. Levothyroxine (T4) is standard; some patients need combination T4/T3 therapy. Dosing and monitoring belong with a physician — self-medicating thyroid hormone risks arrhythmia and bone loss.
Compounds. No peptide treats thyroid disease. Note aggressive cutting protocols (including on GLP-1s) can suppress thyroid output — check Free T3 and Reverse T3 if you stall.
Work down the list, not across it. Adding a compound on top of an unfixed diet is why generic protocols fail. - Retest
6–8 weeks after any dose change; annually if stable. Change one thing at a time, or the retest can't tell you which thing worked.
How to fix it
📚 American Thyroid Association guidelines for hypothyroidism. FDA Safety Communication — biotin interference with immunoassays.
🩸 Test your TSH (Thyroid-Stimulating Hormone)
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Order this test — 10% off → Browse all 102 markers →What TSH (Thyroid-Stimulating Hormone) is usually tested alongside
On its own, one marker is a data point. These panels include TSH (Thyroid-Stimulating Hormone) 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 + 7 more markers — Fatigue, cold intolerance, weight change, hair loss, constipation, low mood, or a 'normal TSH' that never explained how you feel. Women are 5–8x more likely to be affected.
includes this + 11 more markers — Persistently exhausted despite adequate sleep, and either haven't been tested or were told everything is normal.
What moves your TSH (Thyroid-Stimulating Hormone)
2 compounds and 12 supplements 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 TSH (Thyroid-Stimulating Hormone) 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 TSH (Thyroid-Stimulating Hormone) 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.
Biotin interferes with the streptavidin-biotin immunoassays most hormone tests run on. Depending on the assay design it pushes the result falsely HIGH or falsely LOW — there is no single direction to correct for. Hair, skin and nail products are the usual source, and doses in those are far above the RDA.
Stop biotin 48–72 hours before the draw, and check every supplement label rather than just the one labelled biotin.
TSH is pulsatile and diurnal — it peaks overnight and falls through the morning. An 8am and a 2pm draw can differ by roughly a third, which is enough to move someone in or out of the reference range.
Draw early morning, and always at the same time when tracking.
Taking your dose before the draw measures the tablet, not your steady state. Separately, iron, calcium, magnesium and coffee all block absorption — a dose that 'stopped working' is usually one taken with breakfast.
Draw before your morning dose. Keep the tablet four hours from iron and calcium.
Non-thyroidal illness syndrome moves TSH in either direction during any significant illness, and it is not thyroid disease.
Do not diagnose a thyroid problem from a panel drawn while unwell.
What TSH (Thyroid-Stimulating Hormone) 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.
Female pattern shedding is very often nutritional and thyroidal before it is hormonal. Each of these alone can shed hair; together they reliably do.
Ferritin above 50 is the usual threshold for regrowth — normal is not the same as sufficient here. Fix all three and give it 3–6 months; the hair cycle is slow and nothing shows in weeks.
Metabolic adaptation to sustained energy deficit. The body shunts T4 into inactive reverse T3 and down-regulates the whole endocrine axis. TSH stays normal, so a basic thyroid panel misses it entirely.
Restore calories and carbohydrate, take a genuine diet break, deload, sleep. Check ferritin and selenium — both are required for conversion. This is physiology, not a broken thyroid.
Antibodies typically precede dysfunction by years. A normal TSH today does not mean nothing is happening — it means the gland is still compensating.
This is the window where it is worth acting. Monitor TSH and Free T4 every 6–12 months, ensure selenium is adequate, and address gut and vitamin D status. The Autoimmune Thyroid protocol covers the evidence and the noise.
The gland is being pushed harder to produce the same output. Whether to treat is genuinely contested; whether it explains your symptoms is a separate question worth taking seriously.
Check TPO — antibodies change the calculus considerably. Confirm on a second draw (TSH swings across the day and is highest early morning). Fix ferritin, selenium, iodine and energy intake before concluding the gland is the problem.
What to test next
Markers rarely answer alone. These are the ones that put TSH (Thyroid-Stimulating Hormone) in context — each with its own full breakdown.
Frequently asked questions
0.45–4.5 mIU/L Ranges vary by laboratory and assay — always compare to the range printed on your own report.
Many functional practitioners consider 1.0–2.0 mIU/L ideal, arguing the upper reference limit is inflated by undiagnosed thyroid disease in the reference population. This is a genuine area of clinical debate.
Hypothyroidism. High TSH with normal Free T4 = subclinical hypothyroidism.
Hyperthyroidism or over-replacement — anxiety, palpitations, heat intolerance, muscle loss, bone loss.
You can order TSH (Thyroid-Stimulating Hormone) directly through Marek Diagnostics without a doctor's visit — drawn at any Quest Diagnostics location in the US. Code CAMERON applies 10% off automatically.