What your number means
These are for adults who are not pregnant, against a usual range from about 0.4 mIU/L to an upper limit of 4.0 to 4.5.
They help you read a report, and they do not replace your doctor.
- Below the range under about 0.4
- Usual adult range about 0.4 to 4.0
- Upper limit, by lab 4.0 to 4.5
- Above the range over 4.5
For adults who are not pregnant. Your report's own range is the one that applies, and pregnancy uses a different one. Scale in mIU/L.
| Your number | What it means | Source |
|---|---|---|
| 0.2 mIU/L | Below the usual range. A low TSH usually points to an overactive thyroid, but early pregnancy and some medicines can lower it too. Your doctor will usually look at T3 and T4 next. | Medline |
| 1.5 mIU/L | Comfortably inside the usual adult range. | ATA/AACE 2012 guideline |
| 3.5 mIU/L | Still inside the usual adult range, towards the top. If you are pregnant or trying to conceive, the limits are different, so read the pregnancy rows below. | ATA/AACE 2012 guideline |
| 4.5 mIU/L | At or just above the upper limit on many reports. A high TSH usually points to an underactive thyroid. Your doctor may repeat it and add T4 and anti-TPO before deciding anything. | Medline |
| 5.5 mIU/L | Above the usual upper limit. When free T4 is still within its range, NICE calls a TSH above the range subclinical hypothyroidism. NICE's treatment recommendations for adults need the raised TSH on 2 separate tests 3 months apart, so your doctor may repeat the test. | NICE NG145 |
| 7 mIU/L | Still above the range and below 10. For adults under 65 whose TSH stays in this band on 2 separate tests 3 months apart and who have symptoms of an underactive thyroid, NICE says a doctor may consider a 6-month trial of levothyroxine (thyroid tablets). That is your doctor's decision, so please do not start, stop or change any medicine on your own. | NICE NG145 |
| 10 mIU/L | Clearly above the usual range. Please show this report to your doctor soon, and do not start, stop or change any medicine on your own. | Medline |
The ranges
Labs print slightly different limits, and the range on your own report is the one your doctor uses.
The American Thyroid Association does not give one fixed number per trimester in 2017. It asks for a range made for pregnant women, and gives fallbacks when there is none.
| Who | TSH | What it means | Source |
|---|---|---|---|
| Adults, not pregnant | From about 0.4, upper limit 4.0 to 4.5 mIU/L | A typical laboratory reference interval. The upper limit is about 4.0 to 4.5 depending on the lab, and the range on your report is the one that applies to you. | ATA/AACE 2012 guideline, Korevaar, Thyroid Research 2018 |
| Pregnancy, your lab has a pregnancy range | Use that range | The American Thyroid Association's first choice is a TSH range made for pregnant women, ideally from your own lab or a population like yours, for each trimester. | ATA 2017 guideline |
| Pregnancy, no pregnancy range available | Upper limit about 4.0 mIU/L | If there is no pregnancy-specific range, the guideline's fallback is an upper limit of about 4.0 mIU/L, mainly in early pregnancy. TSH also tends to run lower in early pregnancy. | ADLM, Clinical Laboratory News |
| Pregnancy, older fixed limit | 2.5 mIU/L first trimester, 3.0 second and third (older guidance) | The 2011 guideline used these fixed upper limits. The 2017 guideline replaced them with the approach above, but you may still see 2.5 or 3.0 printed on some reports. Ask your doctor which limit they are using. | Korevaar, Thyroid Research 2018 |
The first call is free
Tell Puja what's going on and she will tell you honestly whether she can help.
Things to keep in mind
- TSH is the hormone your brain makes to tell your thyroid how hard to work, so a high TSH usually means the thyroid is underactive and a low one usually means it is overactive.
- If your thyroid is underactive, the tablet your doctor prescribes is what corrects TSH, and food cannot replace it. Take it exactly as advised, and ask your doctor how far apart to keep it from meals, chai and other medicines.
- Reference ranges vary somewhat by laboratory, age and pregnancy status, and illness and some medicines can also move TSH. That is one more reason to read it with your doctor.
Where to go next
- To see what eating around it can look like, read weight loss sample diet charts, how Puja works on weight loss.
- Other numbers people ask about: HbA1c normal range.
Read next: Thyroid diet: eating well with an underactive thyroid.
Words from this page, explained
Sources
Every cut-off above comes from one of these, and the one that supports each number is linked beside it.
- Garber et al., Clinical practice guidelines for hypothyroidism in adults, cosponsored by the AACE and the American Thyroid Association (Endocrine Practice, 2012)
- Alexander et al., 2017 Guidelines of the American Thyroid Association for thyroid disease during pregnancy and the postpartum, Thyroid 27(3):315-389
- Korevaar: The upper limit for TSH during pregnancy (Thyroid Research, 2018)
- ADLM Clinical Laboratory News: Managing thyroid disease in pregnant women (2017)
- MedlinePlus: TSH (Thyroid-stimulating hormone) Test
- NICE guideline NG145: Thyroid disease, assessment and management (2019)
This is general information, not medical advice. Follow your doctor on any medicine, its dose and its timing.
Not sure what your TSH means?
Send Puja the report. She will read it with you in plain words, and say what she would look at on your plate. Your doctor stays in charge of the medicine.
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