Thyroid

TSH (thyroid stimulating hormone)

Updated 2026-10-14Written for education by the Zenlo Health editorial teamHow we review
Quick answerTSH (thyroid stimulating hormone) is the standard first test for thyroid function. A high TSH usually means an underactive thyroid, and a low TSH usually means an overactive one.
Fasting and prepNo fasting needed. If you take biotin, ask your clinician about pausing it first, since it can interfere with some thyroid assays.
Typical turnaroundUsually 1 to 2 days.
Also calledtsh test, thyroid test

What it measures

Your pituitary gland releases TSH to tell your thyroid how hard to work. When thyroid hormone runs low, TSH climbs. Labs often add free T4, free T3, or thyroid antibodies when TSH is abnormal.

Who should consider it

  • People with fatigue, weight change, cold or heat intolerance, or hair and skin changes
  • Anyone with a family history of thyroid disease
  • People on thyroid medicine who need monitoring

How to read your result

  • Many labs list about 0.4 to 4.0 mIU/L as typical. Ranges vary.
  • A mildly high TSH often needs a repeat test and free T4 before any treatment.
  • Symptoms count as much as the number.

Reference ranges differ between labs. Use the range printed on your own report.

What to do next

If TSH is off, free T4 and thyroid antibodies (TPO) clarify the cause.

Where to order TSH

These sellers include an independent physician order. You pay online and visit a partner lab. Availability, price, and lab network vary, so confirm at checkout.

Private MD Labs

Online lab seller
  • Says 4,500+ Quest and Labcorp locations
  • Every order reviewed by a physician. Says you pay $1 to start and the rest after results.
  • Secure online portal with plain-English explanations. Says many results arrive overnight.
Visit site Read review

HealthLabs

Online lab seller
  • Says 4,500+ labs, including Quest and Labcorp
  • Online or by phone. No doctor referral or insurance needed.
  • Secure HealthLabs account. Says 1 to 3 business days.
Visit site Read review

Walk-In Lab

Online lab seller
  • Lab network not named on its homepage
  • Online, no insurance or doctor order needed. Shows a $6 physician fee per order on popular tests.
  • Online account. Turnaround not stated on its homepage.
Visit site Read review

Quest Health

Lab-run
  • Quest, 2,000+ locations
  • Buy online and book a Quest appointment. An independent provider is involved.
  • Online as soon as ready, with an email alert. Provider discussion included at no extra cost.
Visit site Read review

Seller details come from each seller's own site and can change. Confirm price, lab location, and state availability at checkout.

Questions people ask

Is TSH enough to check my thyroid?

It is the best single screening test. If it is abnormal or symptoms persist, free T4 and antibodies add detail.

Can I test TSH without a doctor?

Yes. Online sellers offer TSH alone or in thyroid panels. Bring any abnormal result to your clinician.

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