TSH (Thyroid Stimulating Hormone)

Hormone that regulates thyroid function

19/22Providers
Thyroid FunctionCategory
energyReference
Widely Available

19 of 22 providers

Category

Thyroid Function

Reference Range

energy

What is TSH (Thyroid Stimulating Hormone)?

TSH (Thyroid Stimulating Hormone) is a hormone produced by your pituitary gland that regulates your thyroid gland's production of thyroid hormones (T4 and T3). Think of TSH as the "thermostat"for your thyroid:when thyroid hormone levels drop, your pituitary releases more TSH to tell the thyroid to produce more hormone. When thyroid hormone levels are sufficient, TSH drops.

Here's the counterintuitive part that confuses many people:high TSH means your thyroid is underactive (hypothyroidism), while low TSH means your thyroid is overactive (hyperthyroidism). It's an inverse relationship—TSH goes up when thyroid function goes down, like a thermostat cranking up the heat when the house is too cold.

TSH is the single most important initial screening test for thyroid function. However, TSH alone doesn't tell the full story—you also need Free T4 and Free T3 to understand what's actually happening at the tissue level. Some people have normal TSH but low Free T3 due to conversion problems, and they'll have hypothyroid symptoms despite "normal"labs.

Why TSH Alone Isn't Enough

  • Central hypothyroidism:Pituitary gland failure causes low TSH + low thyroid hormones (rare but serious)
  • T4→T3 conversion problems:Normal TSH/T4 but low Free T3 due to stress, selenium deficiency, chronic illness
  • Subclinical hypothyroidism:Elevated TSH with normal Free T4—controversial whether to treat
  • Hashimoto's (autoimmune) thyroiditis:TSH may be normal early on but TPO antibodies are elevated

Optimal vs Standard Ranges

Optimal (Longevity)
0.5-2.5 mIU/L▼
  • Best metabolic function, energy, and symptom control
  • Many functional medicine doctors target this range
Low-Normal (Borderline Low)
2.5-4.0 mIU/L▼
  • Within standard range but may have subtle hypothyroid symptoms
  • Consider retesting in 3-6 months or checking antibodies
Subclinical Hypothyroidism
4.0-10.0 mIU/L▼
  • Thyroid struggling but Free T4 still normal
  • Controversial treatment threshold
  • Consider treatment if symptomatic or trying to conceive
Overt Hypothyroidism
>10.0 mIU/L▼
  • Clear thyroid failure;requires treatment
  • Free T4 will be low
  • Start levothyroxine and retest in 6-8 weeks
Standard lab range: energy
Sources:PMID:37696273, PMID:24195179, PMID:20858880

Scientific Evidence

Hashimoto's thyroiditis:Autoimmune attack on thyroid gland. Most common cause of hypothyroidism in iodine-sufficient countries (5-10% prevalence, 7:1 female:male ratio). Check TPO antibodies.|Iodine deficiency:Rare in developed countries (iodized salt) but most common cause worldwide. Thyroid can't make T4/T3 without iodine.|Thyroid surgery or radioactive iodine treatment:Surgical removal or ablation of thyroid gland for cancer, nodules, or hyperthyroidism.|Medications:Lithium (bipolar disorder), amiodarone (heart arrhythmias), high-dose iodine, interferon.|Pituitary or hypothalamus disorders:Rare. Tumor, trauma, or Sheehan's syndrome (postpartum pituitary necrosis) causes low TSH despite hypothyroidism ("central hypothyroidism").|Congenital hypothyroidism:Born with absent or malfunctioning thyroid gland. Screened at birth in developed countries.

Graves'disease:Autoimmune condition where antibodies stimulate thyroid to overproduce hormone. Most common cause of hyperthyroidism. Associated with bulging eyes (Graves'ophthalmopathy).|Toxic nodular goiter:Thyroid nodules autonomously produce excess thyroid hormone independent of TSH control.|Thyroiditis (inflammation):Subacute, postpartum, or silent thyroiditis causes stored thyroid hormone to leak out, temporarily suppressing TSH. Usually self-limited.|Excessive thyroid hormone medication:Over-replacement with levothyroxine or taking thyroid hormone without medical supervision (weight loss abuse).|Pituitary adenoma (rare):TSH-secreting tumor causes high thyroid hormones + high TSH (opposite of usual pattern).

Source:If starting or adjusting thyroid medication:Retest TSH, Free T4, Free T3 after 6-8 weeks of any dose change.|Once stable on treatment:Retest every 6-12 months to ensure dose remains appropriate.|If subclinical hypothyroidism (TSH 4-10):Retest in 3-6 months to see if it progresses. Check TPO antibodies to assess autoimmune risk.|If optimizing for longevity/symptoms:Retest 3 months after implementing iodine, selenium, or lifestyle changes to assess impact.|Routine screening:Every 5 years starting at age 35, or sooner if family history, autoimmune disease, or symptoms. (PubMed)

TSH as Screening Test

TSH is the most sensitive single test for primary hypothyroidism and hyperthyroidism. A normal TSH has 98% negative predictive value for excluding thyroid dysfunction in ambulatory patients. However, TSH may be normal in central hypothyroidism (pituitary failure) and doesn't reflect tissue thyroid status in T4→T3 conversion disorders.

Source:Garber JR, et al. Clinical practice guidelines for hypothyroidism in adults. Thyroid. 2012;22(12):1200-1235. (PubMed)

Optimal TSH Range Controversy

While standard lab range is 0.4-4.0 mIU/L, population studies show 95% of healthy individuals without thyroid disease have TSH <2.5 mIU/L. The upper limit of 4.0 includes many people with subclinical hypothyroidism. Many functional medicine practitioners target 0.5-2.5 mIU/L for optimal metabolic function.

Source:Wartofsky L, Dickey RA. The evidence for a narrower thyrotropin reference range is compelling. J Clin Endocrinol Metab. 2005;90(9):5483-5488. (PubMed)

Hashimoto's Thyroiditis Prevalence

Hashimoto's is the most common cause of hypothyroidism in iodine-sufficient countries, affecting 5-10% of the population with a 7:1 female:male ratio. It's characterized by elevated TPO and/or thyroglobulin antibodies. Selenium supplementation (200 mcg/day) reduces TPO antibodies by ~40% in multiple trials.

Source:Chiovato L, et al. Hypothyroidism in Context:Where We've Been and Where We're Going. Adv Ther. 2019;36(Suppl 2):47-58. (PubMed)

Subclinical Hypothyroidism Treatment Debate

Subclinical hypothyroidism (TSH 4-10 with normal Free T4) affects 4-10% of adults. Treatment remains controversial. Evidence supports treatment if:TSH >10, elevated TPO antibodies, symptomatic, pregnant/trying to conceive, or progressive TSH rise. For TSH 4-7 without symptoms, watchful waiting may be appropriate.

Source:Bekkering GE, et al. Thyroid hormones treatment for subclinical hypothyroidism:a clinical practice guideline. BMJ. 2019;365:l2006. (PubMed)

Which Providers Test TSH (Thyroid Stimulating Hormone)?

Superpower
Included in panel
Blueprint
Included in panel
Mito Health
Included in panel
WHOOP
Included in panel
Function
Included in panel
InsideTracker
Included in panel
Marek Comp.
Included in panel
Marek Complete
Included in panel
Marek Exec.
Included in panel
Life Ext.
Included in panel
Labcorp
Included in panel
Everlywell
Included in panel
Empirical Health
Included in panel
SiPhox Health
Included in panel
Healthspan
Included in panel
Hims Base
Included in panel
Hims Adv.
Included in panel
Vitality Std
Included in panel
Vitality Elite
Included in panel

Full Provider Comparison

ProviderIncludesAnnual CostBiomarkers
SuperpowerSuperpower✓$199100+ (150 with ratios)
WHOOP Advanced LabsWHOOP Advanced Labs✓$34965
Labcorp OnDemandLabcorp OnDemand✓$39830+
Life ExtensionLife Extension✓$48640+
EverlywellEverlywell✓$444288
Mito HealthMito Health✓$349100+
InsideTrackerInsideTracker✓$76154
Function HealthFunction Health✓$365160+
Marek Health BaseMarek Health Base—$25065
Marek Health ComprehensiveMarek Health Comprehensive✓$49570+
Marek Health CompleteMarek Health Complete✓$895100+
Marek Health ExecutiveMarek Health Executive✓$1950150+
BlueprintBlueprint✓$37580+
Quest HealthQuest Health—$Varies75+
Empirical HealthEmpirical Health✓$190100+
Oura Health PanelsOura Health Panels—$9950
SiPhox HealthSiPhox Health✓$12460
Hims Labs BaseHims Labs Base✓$19950
Hims Labs AdvancedHims Labs Advanced✓$499120+
HealthspanHealthspan✓$418870-80+
Vitality Blueprint StandardVitality Blueprint Standard✓$37585
Vitality Blueprint EliteVitality Blueprint Elite✓$700128

Related Biomarkers

Other biomarkers in the Thyroid Function category:

Free T4 (Thyroxine) Free T3 (Triiodothyronine) TPO Antibodies (Thyroid Peroxidase) Thyroglobulin Antibodies Iodine Selenium T3 Uptake Total T4

Frequently Asked Questions

What is TSH (Thyroid Stimulating Hormone)?

Hormone that regulates thyroid function

What is the optimal range for TSH (Thyroid Stimulating Hormone)?

The standard reference range for TSH (Thyroid Stimulating Hormone) is energy. Optimal ranges may differ based on individual health goals and expert recommendations.

Which blood test providers include TSH (Thyroid Stimulating Hormone)?

19 out of 22 blood testing providers include TSH (Thyroid Stimulating Hormone) in their panels. This biomarker is widely available across major providers.

What category does TSH (Thyroid Stimulating Hormone) fall under?

TSH (Thyroid Stimulating Hormone) is categorized under Thyroid Function. This category includes biomarkers that help assess related aspects of health and wellness.

Medical Disclaimer

This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.

Last reviewed:2026-02-20