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Thyroid Stimulating Hormone (TSH) with Mass Concentration Measurement

Published: August 9, 2026Updated: August 16, 2026

This test measures your thyroid-stimulating hormone, a key hormone that regulates your thyroid function. It helps doctors assess whether your thyroid is working properly.

Quick summary

["Your TSH level helps determine if your thyroid is underactive or overactive."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
24459-0
Short code
TSH 20M p TRH SerPl-mCnc
Synonyms
TSH 20M p TRH SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.4
Ref high
4
Critical range
0.1 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85610
SNOMED
396252006
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Matters

Thyroid-stimulating hormone (TSH) is produced by your pituitary gland and signals your thyroid to produce thyroid hormones (like thyroxine, or T4). Low or high TSH levels can indicate conditions such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). This test is often the first step in diagnosing thyroid disorders.

How the Test Works

Your blood sample is taken from a vein in your arm. The lab uses a sensitive immunoassay method to detect and measure the amount of TSH in your serum. This test does not require fasting.

What to Expect Before the Test

There are no special preparations needed for this test. You can eat and drink normally on the day of your appointment. If you’re on thyroid medication, let your healthcare provider know before the test.

Possible Results and Next Steps

If your TSH level is outside the expected range, your doctor may recommend further testing, such as checking thyroid hormones (like T4 or free T4) or other blood tests to understand the cause of your symptoms.

Reference range

Adult: 0.4-4.0 mIU/LN/A

Specimen: serum

Take your thyroid medication after the blood draw if applicable. No fasting required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

TSH Level

Frequently asked questions

What does a high TSH level usually mean?
A high TSH level often suggests your thyroid is not producing enough thyroid hormones, which can lead to symptoms like fatigue, weight gain, or cold sensitivity. It may indicate hypothyroidism.
What does a low TSH level usually mean?
A low TSH level may indicate your thyroid is producing too much hormone, possibly due to hyperthyroidism, Graves’ disease, or other conditions. Symptoms could include weight loss, anxiety, or rapid heartbeat.
Can TSH levels change over time?
Yes, TSH levels can fluctuate due to factors like stress, pregnancy, certain medications, or thyroid disease progression. Regular monitoring by your doctor can help track changes and guide treatment.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy