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Thyroid Stimulating Hormone (TSH) with Immunoassay Method

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

This blood test measures your thyroid-stimulating hormone, a key hormone that helps regulate your metabolism and energy levels by signaling your thyroid gland to produce thyroid hormones.

Quick summary

["Your TSH helps doctors check if your thyroid is working properly."]

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

Key facts at a glance

LOINC
73204-0
Short code
Pioglitazone ind plt IgM SerPl Ql FC
Synonyms
Pioglitazone ind plt IgM SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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 Is Done

Your doctor may order a TSH test to evaluate thyroid function, diagnose conditions like hypothyroidism (low thyroid activity) or hyperthyroidism (overactive thyroid), or monitor thyroid treatment. It’s often the first test for thyroid issues due to its sensitivity and ease.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the blood draw if your test includes other thyroid-related measurements. Wear comfortable clothing and bring your ID for the appointment.

How the Test Works

A small needle will draw blood from a vein in your arm. The sample is sent to a lab where an immunoassay detects TSH levels in your serum or plasma. Results are compared to standard reference ranges to assess thyroid function.

What the Results Mean

High TSH levels often indicate hypothyroidism, while low levels may suggest hyperthyroidism or other thyroid disorders. Your doctor will interpret results in context with your symptoms and other tests.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

TSH is a critical biomarker for thyroid health. Abnormal levels can signal underlying conditions requiring treatment, such as thyroid nodules, pituitary disorders, or autoimmune diseases. Regular monitoring with TSH helps manage long-term thyroid conditions effectively.

Short name

TSH Level

Frequently asked questions

What causes TSH levels to be checked?
TSH levels are checked if you have symptoms like fatigue, weight changes, cold intolerance, or hair loss, or if you have a family history of thyroid disease. Doctors also use it to monitor thyroid replacement therapy or screen for thyroid issues during pregnancy.
What do TSH results outside the normal range mean?
Results outside the typical range may indicate an underactive or overactive thyroid. Your doctor will discuss these findings with you and may recommend further tests or adjustments to your treatment plan.
Can lifestyle factors affect TSH test results?
Yes, stress, diet (especially iodine intake), and certain medications (like lithium or amiodarone) can influence TSH levels. Your doctor may ask about these factors when reviewing your results.
  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