Complete Testing & Optimization Guide
Optimal ranges, provider comparison, and strategies to improve your TSH (Thyroid Stimulating Hormone) levels
Included in 9 of 10 major testing providers
Thyroid Function
energy
Abnormal TSH (Thyroid Stimulating Hormone) levels can indicate underlying health issues that may go undetected without proper testing. Regular monitoring helps catch problems early when they're most treatable.
Understanding your TSH (Thyroid Stimulating Hormone) levels enables targeted interventions, tracks treatment effectiveness, and helps optimize your overall health and performance.
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.
Bottom line: TSH and Free T4 alone miss people with conversion problems. Free T3 is the only way to know if you have enough active thyroid hormone at the tissue level.
| Range Type | Level | Clinical Significance |
|---|---|---|
| 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
<0.4 mIU/L
Treat Underlying Hypothyroidism (if TSH >2.5-4.0)
Optimize Thyroid-Supporting Nutrients
Address Hashimoto's Thyroiditis (if TPO antibodies elevated)
Lifestyle Factors
Note: Treat Hyperthyroidism (if TSH <0.4)
Note: Persistent fatigue, low energy despite adequate sleep|Weight gain or inability to lose weight|Cold intolerance (always feeling cold, cold hands/feet)|Brain fog, poor concentration, memory problems|Depression, low mood, anxiety|Dry skin, brittle nails, hair loss or thinning (especially outer third of eyebrows)|Constipation, sluggish digestion|Slow heart rate (bradycardia)|Muscle weakness, joint pain|Heavy or irregular menstrual periods|Infertility or difficulty conceiving|Puffy face, swelling around eyes|High cholesterol (especially LDL)
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.
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.
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.
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.
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.
| Provider | Includes Test | Annual Cost | Total Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ |
 WHOOP Advanced Labs | — | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $468 | 83 | |
| ✓ | $798 | 100+ | |
 InsideTracker | ✓ | $680 | 48 |
 Function Health | ✓ | $499 | 100+ |
| ✓ | $900 | 70+ | |
| ✓ | $1150 | 110 | |
| — | $Varies | 75+ |
Choose from 9 providers that include this biomarker in their panels
TSH (Thyroid Stimulating Hormone) is a thyroid function biomarker that Hormone that regulates thyroid function The normal reference range is energy. Regular testing helps track changes and identify potential health issues early.
9 out of 10 major blood testing providers include TSH (Thyroid Stimulating Hormone) in their standard panels. These include Superpower, Blueprint, Mito Health and others.
For most people, testing TSH (Thyroid Stimulating Hormone) 2-4 times per year is recommended to establish baseline levels and track trends. If you have abnormal results or are actively working to optimize this biomarker, more frequent testing (quarterly) may be beneficial. Always consult with your healthcare provider for personalized testing frequency recommendations.
The standard laboratory reference range for TSH (Thyroid Stimulating Hormone) is energy. However, many functional medicine practitioners recommend tighter "optimal" ranges for peak health and performance. Your ideal range may vary based on your age, sex, health goals, and other individual factors. Work with a healthcare provider familiar with optimal ranges to determine your target levels.
Most direct-to-consumer blood testing services that include TSH (Thyroid Stimulating Hormone) provide the physician order as part of their service. However, some states have restrictions on direct-to-consumer testing. Check with your chosen provider about availability in your state and whether they provide the necessary physician authorization.
Primary screening test for thyroid disorders. Elevated TSH indicates hypothyroidism;low TSH suggests hyperthyroidism. Affects metabolism
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs and before making decisions about blood testing.
