Quick answer: the TSH normal range widens with age because the upper limit climbs, from 3.60 mIU/L at 20 to 29 to 4.70 at 60 to 69, 5.60 at 70 to 79 and 6.30 at 80 and over in thyroid-healthy, antibody-negative Americans, while the lower limit stays near 0.4. In pregnancy the American Thyroid Association's 2026 guideline prefers lab- and trimester-specific ranges and uses 4.0 mIU/L as the diagnostic threshold when those are not available.
2.5th to 97.5th percentile of the NHANES III reference population (13,296 people), Boucai, Hollowell and Surks, Thyroid 2011, Table 1. mIU/L is the same number as µIU/mL.
TSH normal range by age: the full table
The chart comes from NHANES III, the national survey behind most US TSH ranges. The reference population excludes anyone with thyroid disease, thyroid medicine, TPO or thyroglobulin antibodies, or a TSH above 10 or below 0.1 mIU/L. The last column keeps people with antibodies, which is closer to the mix of patients a lab actually sees.
| Age | 2.5th percentile | Median | 97.5th percentile | 97.5th, including antibody-positive |
|---|---|---|---|---|
| 13 to 19 | 0.41 | 1.30 | 3.78 | 3.98 |
| 20 to 29 | 0.40 | 1.30 | 3.60 | 3.98 |
| 30 to 39 | 0.38 | 1.25 | 3.60 | 4.17 |
| 40 to 49 | 0.44 | 1.40 | 3.90 | 4.75 |
| 50 to 59 | 0.49 | 1.50 | 4.20 | 5.07 |
| 60 to 69 | 0.46 | 1.66 | 4.70 | 5.56 |
| 70 to 79 | 0.47 | 1.74 | 5.60 | 7.11 |
| 80 and over | 0.44 | 1.90 | 6.30 | 6.90 |
All values in mIU/L. Across all ages the reference range was 0.42 to 4.30. The authors' regression found the 97.5th percentile rises by about 0.031 mIU/L for every year of age, while the lower limit barely moves. A Scottish study of 153,127 people without thyroid disease (TEARS) found the same shape: the 97.5th percentile went from 3.98 mIU/L at 31 to 40 to 5.94 over 90, and the 2.5th percentile fell slightly, from 0.51 to 0.31.
Why TSH rises with age
Surks and Hollowell showed the whole TSH distribution shifts upward in older people, not just a tail of people with thyroid disease. Among Americans without thyroid disease, 10.6% of 20 to 29 year olds had a TSH above 2.5 mIU/L, against 40% of people 80 and over, and 14.5% of the over-80s were above 4.5. Seventy percent of older people with a TSH above 4.5 were still inside their age-specific range, so a single adult range overstates mild (subclinical) hypothyroidism in older adults. Among people with a TSH above 4.5, the share with thyroid antibodies fell from 67.4% at 40 to 49 to 40.5% at 80 and over: a high TSH in an older person is less often autoimmune.
Race and sex
The same NHANES data show lower TSH in Black Americans: the all-ages reference range was 0.36 to 3.70 mIU/L, against 0.49 to 4.60 in White and 0.46 to 4.37 in Mexican American participants. Women had slightly lower 2.5th and 50th percentiles than men. Few labs adjust for any of this, so it is worth asking how your result compares with people like you. For what a high or low TSH means, see the main TSH guide.
TSH normal range for children and teens
Babies and young children run higher than adults, especially in the first month of life. These are ARUP's pediatric ranges:
| Age | TSH (mIU/L) |
|---|---|
| 0 to 3 days | 5.17 to 14.60 |
| 4 to 30 days | 0.43 to 16.10 |
| 1 to 24 months | 0.62 to 8.05 |
| 2 to 6 years | 0.54 to 4.53 |
| 7 to 11 years | 0.66 to 4.14 |
| 12 to 19 years | 0.53 to 3.59 |
| 20 and over | 0.27 to 4.20 |
TSH normal range in pregnancy by trimester
The pregnancy hormone hCG stimulates the thyroid in the first trimester, so TSH usually drops. The American Thyroid Association (ATA) has changed its advice three times:
ATA 2011 guideline, Recommendation 2, for labs without their own trimester ranges. The 2017 and 2026 guidelines moved away from these fixed limits.
| Guideline | What it says about TSH in pregnancy |
|---|---|
| ATA 2011 | Use trimester-specific ranges; if the lab has none, use 0.1 to 2.5 (first), 0.2 to 3.0 (second) and 0.3 to 3.0 mIU/L (third trimester) |
| ATA 2017 | Prefer local, trimester-specific ranges; if unavailable, lower the non-pregnant range in the first trimester (about 0.4 off the lower limit and 0.5 off the upper) or use an upper limit of about 4.0 mIU/L |
| ATA 2026 | Use lab- and trimester-specific ranges where available; otherwise 4.0 mIU/L is the diagnostic threshold for hypothyroidism. Women already on levothyroxine: a reasonable target is 0.5 to 2.5 mIU/L |
Under the 2026 guideline, subclinical hypothyroidism with a TSH above 10 mIU/L warrants treatment, milder cases in the first trimester may be treated after a confirmatory test, and cases found later are monitored every 4 to 6 weeks, according to a 2026 review of the ATA and UK RCOG updates. In pregnancy, TSH is a test to manage with your obstetrician, not on your own.
Worked examples: the same TSH at 35 and at 76
TSH 5.2 mIU/L with a normal free T4. At 35, that is above the lab range (4.20) and the NHANES 97.5th percentile for 30 to 39 (3.60). It fits mild (subclinical) hypothyroidism, and a TPO antibody test is the usual next step. At 76, the same number is flagged high by the lab but sits inside the NHANES range for 70 to 79 (up to 5.60). The Boucai paper's own worked example puts the range for a 75-year-old White woman at 0.51 to 5.22 mIU/L, and for a 22-year-old Black man at 0.37 to 3.46. Either way, repeat the test with free T4 before anyone talks about treatment, and make that decision with your doctor.
TSH 0.3 mIU/L at 68. Below the 2.5th percentile at every age (0.38 to 0.49), and the lower limit does not loosen with age. A low TSH in an older adult deserves follow-up with free T4 and free T3, because an overactive thyroid raises the risk of heart rhythm problems and bone loss.
How to get a TSH result you can compare
- Test in the morning, and at the same time of day when you retest; TSH varies over the day (MedlinePlus).
- Stop biotin for 2 days before the test (ATA). It can make thyroid results look abnormal.
- Repeat an out-of-range TSH with free T4 before acting on it.
- Compare against an age-appropriate range as well as the one printed on your report, and bring both to your doctor.
How to test TSH at home
SiPhox Health includes TSH on five of its six panels; Hormone Focus is the only one without it.
| SiPhox panel | Thyroid markers | Per test with shipping |
|---|---|---|
| Thyroid Focus | TSH, free T4, free T3, TPO and thyroglobulin antibodies, 2 ratios | $149 |
| Longevity Essentials | TSH | $149 |
| Heart & Metabolic | TSH | $149 |
| Ultimate 360 | The full Thyroid Focus set plus 55 other markers | $274 |
| GLP Optimization | TSH, free T4, TSH:T4 ratio | $224 |
| If you are | Test | Choose |
|---|---|---|
| Under 50 with tiredness, weight change or feeling cold | TSH, free T4, free T3, TPO antibodies | Thyroid Focus ($124 + $25) |
| Over 65 with a borderline-high TSH on a past test | Repeat TSH with free T4 and antibodies to see whether it is autoimmune | Thyroid Focus ($124 + $25) |
| Screening thyroid alongside heart and metabolic health | TSH | Longevity Essentials or Heart & Metabolic |
| Pregnant or trying to conceive | Trimester-specific TSH and free T4 | Your obstetrician or clinic |
Our at-home thyroid test guide compares SiPhox with other kits, and the hypothyroidism blood test page explains which markers answer which question.
A note on home samples: SiPhox's partner lab tests capillary blood collected from the upper arm. SiPhox says its results show a 95% to 99% correlation with venous draws in its own quarterly comparisons against Labcorp and Quest, but it has not published a study of the EasyDraw device, and results come without an included doctor review. If a result would change a treatment decision, confirm it with a venous test through your doctor.
Thyroid Focus
A full thyroid workup including both thyroid antibodies, plus core lipids.
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Longevity Essentials
The default panel: heart, metabolic, hormone and inflammation markers in one draw.
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Heart & Metabolic
Lipids plus kidney and liver function: the panel for cardiovascular and metabolic risk.
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Frequently asked questions
What is a normal TSH level for a 70-year-old?
In the NHANES III reference population, 0.47 to 5.60 mIU/L at 70 to 79, with a median of 1.74. Many labs still print one adult range with an upper limit of about 4.2 to 4.5, so a 70-year-old can be flagged high while normal for their age.
Is a TSH of 4.5 normal for an older adult?
For people 60 to 69 the 97.5th percentile is 4.70 mIU/L, and at 70 to 79 it is 5.60, so 4.5 is within the age range. Under 50 it is above it. Repeat it with free T4 and TPO antibodies and discuss it with your doctor.
Does TSH increase with age?
Yes. The median rises from 1.30 mIU/L in your 20s to 1.90 at 80 and over, and the upper limit rises by about 0.031 mIU/L per year of age (NHANES III).
What should TSH be in the first trimester?
The ATA's 2026 guideline prefers your lab's own trimester-specific range; without one, 4.0 mIU/L is the diagnostic threshold. The older 2011 fixed range was 0.1 to 2.5 mIU/L. Women already on levothyroxine aim for 0.5 to 2.5.
What is a normal TSH for a teenager?
ARUP uses 0.53 to 3.59 mIU/L for ages 12 to 19. In NHANES III, antibody-negative 13 to 19 year olds ranged from 0.41 to 3.78.
Sources
- Boucai L, Hollowell JG, Surks MI. An approach for development of age-, gender-, and ethnicity-specific thyrotropin reference limits (NHANES III). Thyroid 2011
- Surks MI, Hollowell JG. Age-specific distribution of serum thyrotropin and antithyroid antibodies in the US population. J Clin Endocrinol Metab 2007
- Hollowell JG et al. Serum TSH, T4 and thyroid antibodies in the United States population (NHANES III). J Clin Endocrinol Metab 2002
- Vadiveloo T et al. Age- and gender-specific TSH reference intervals in people with no obvious thyroid disease in Tayside, Scotland (TEARS). J Clin Endocrinol Metab 2013
- Stagnaro-Green A et al. Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and postpartum. Thyroid 2011
- Alexander EK et al. 2017 Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and the postpartum. Thyroid 2017
- Korevaar TIM et al. American Thyroid Association 2026 guidelines for thyroid disease in preconception, pregnancy, and postpartum. Thyroid 2026
- Athanasiadou KI et al. Navigating the RCOG 2025 and ATA 2026 guideline updates on the management of thyroid disorders during pregnancy. Case Rep Womens Health 2026
- ARUP Laboratories Test Directory: Thyroid stimulating hormone
- MedlinePlus Lab Tests: TSH (thyroid stimulating hormone) test
- American Thyroid Association: Thyroid function tests
- SiPhox Health: panel comparison (checked 29 Sep 2026)
- SiPhox Health: Thyroid Focus panel