TSH
Measures pituitary TSH, the usual first blood test for how hard your thyroid is being asked to work. Helps flag under- or overactive thyroid patterns before deeper tests.
Your thyroid sets the idle speed for energy, weight, temperature, and mood. TSH is the signal from the pituitary that tells the thyroid to make more or less hormone. When the thyroid is sluggish, TSH usually climbs. When the thyroid is overactive, TSH often drops. Doctors start here because it is sensitive, cheap, and easy to repeat; free T4 and other tests fill in the rest of the picture when TSH looks off.
Self-Pay Price Comparison
| Provider | Price | vs. Highest | Order |
|---|---|---|---|
Quest QuestHealth self-pay | $44.10 | Save $4.90 | Order · Quest |
LabCorp Labcorp OnDemand | $49.00 | Highest | Order · LabCorp |
GoodLabs Discount lab network | $5.00Best value | Best price | Order · GoodLabs |
What This Test Measures
This order returns pituitary TSH as a single number in microunits per milliliter. Here is what that line is actually reading:
Pituitary signal that tells the thyroid to make more or less hormone; a high value usually means the gland is being pushed harder for an underactive pattern, a low value usually means the gland is already flooded with hormone or the signal is damped by medicines or illness.
How to Read Your Results
Your report prints TSH next to a reference band that shifts slightly by lab and life stage. Here is how to read the three flags people see most often:
| Marker | Normal Range | If Flagged | What It Might Mean |
|---|---|---|---|
| TSH (general adult screen) | Often about 0.5-5 microunits per milliliter (uIU/mL); some labs use a higher upper limit for older adults (MedlinePlus Medical Encyclopedia, TSH test). | high | A high TSH usually fits an underactive thyroid, but medicines, recovery from illness, and pituitary problems can twist the story. MedlinePlus notes experts disagree slightly on the upper limit. One result in isolation rarely tells the full story. |
| TSH (treated hypothyroidism) | Many treated adults aim between about 0.5 and 4.0 uIU/mL unless pregnancy, thyroid cancer follow-up, or pituitary disease changes the plan (MedlinePlus Medical Encyclopedia, TSH test). | abnormal | Out-of-range TSH on levothyroxine usually means the dose needs review, but timing of the draw and brand switches also move the number. |
| TSH (low) | Same reference band as above; values below the lab low limit are flagged low. | low | Low TSH often goes with an overactive thyroid, too much thyroid hormone, or certain medicines (steroids, dopamine, opioids per MedlinePlus). Imaging iodine and supplements that contain thyroid hormone can also suppress TSH. |
When to Order
Annual baseline
Some adults add TSH to routine labs, especially with family thyroid disease, autoimmune illness, or new cholesterol issues.
Fatigue, weight change, cold or heat intolerance
Those symptoms overlap many problems, but TSH is the usual first thyroid blood check when the story fits.
Fast heartbeat, tremor, anxiety, or unexplained weight loss
Hyperthyroid pattern symptoms; TSH plus free T4 sorts most cases.
Starting levothyroxine or changing the dose
Repeat TSH shows whether replacement is enough, too much, or still settling.
Planning pregnancy or early pregnancy
MedlinePlus notes trimester-specific targets; your doctor may want TSH in a tighter band than the usual adult screen.
Prep & Logistics
- Fasting
- Typically no fasting
- Sample
- Blood draw
- Results
- Usually 24-48 hours; many portals update the same day or the next.
- Referral
- Often self-order (check local rules)
- Markers
- TSH in microunits per milliliter (often shown as mIU/L or uIU/mL depending on the lab).
Tests That Pair With This One
Thyroid hormone level when TSH is off, symptoms disagree with TSH, or dose changes need a second number.
Active T3 when hyperthyroid symptoms persist or TSH and free T4 still do not match the story.
Total T3 backup when panels still report it or protein shifts make free T3 hard to interpret alone.
FAQ
Is TSH enough or do I need free T4 on the first draw?
Most screening starts with TSH alone—it is sensitive and cheap. Add free T4 when TSH is off, symptoms do not match the number, or you are adjusting thyroid medication and need the pair.
My TSH is 6. Am I broken?
A mild bump can be early hypothyroidism, lab variation, or recent illness. Your doctor often repeats the test, checks free T4, and looks at symptoms before starting medicine.
I take biotin for hair. Does that matter?
MedlinePlus warns that biotin can skew thyroid blood tests. Tell the lab and your doctor; they may ask you to stop biotin for a few days before the draw.
Why test in the morning?
MedlinePlus notes TSH drifts through the day; morning draws are easier to compare visit to visit.
Sources
Prices pulled directly from provider websites and verified by hand. Reference ranges sourced from MedlinePlus. Not generated by AI.
- GoodLabs - product page (pricing context)(verified 2026-03-23)
- Quest - consumer lab shop (pricing context)(verified 2026-03-23)
- LabCorp OnDemand - TSH (pricing context)(verified 2026-03-23)
- MedlinePlus - TSH (thyroid-stimulating hormone) test overview
- MedlinePlus Medical Encyclopedia - TSH test (reference range, medicines, pregnancy notes)
- Clinical context: LabRecon editorial team. Not medical advice. For informational use only.
Third-generation immunometric assay for thyroid-stimulating hormone. Primary screen for hypothyroidism and hyperthyroidism.