Thyroid Function Test – TSH (Thyroid Stimulating Hormone)
Test Name: TSH (Thyroid Stimulating Hormone) Test
What is the TSH Test?
The TSH test measures the level of Thyroid Stimulating Hormone in the blood. TSH is produced by the pituitary gland and controls the activity of the thyroid gland, which regulates metabolism, energy levels, body temperature, and overall hormonal balance.
This test is the most sensitive and primary screening test for diagnosing thyroid disorders.
Why is the TSH Test Done?
The TSH test helps to:
- Diagnose hypothyroidism (underactive thyroid)
- Diagnose hyperthyroidism (overactive thyroid)
- Monitor thyroid treatment (thyroxine or antithyroid drugs)
- Evaluate unexplained symptoms like:
- Weight gain or weight loss
- Fatigue or weakness
- Hair fall
- Menstrual irregularities
- Anxiety or depression
Normal Range of TSH (Blood Test)
| Age Group | Normal TSH Range |
|---|---|
| Adults | 0.4 – 4.0 mIU/L |
| Pregnant (1st trimester) | 0.1 – 2.5 mIU/L |
| Pregnant (2nd trimester) | 0.2 – 3.0 mIU/L |
| Pregnant (3rd trimester) | 0.3 – 3.0 mIU/L |
⚠️ Note: Normal ranges may vary slightly depending on laboratory methods and reference standards.
Interpretation of TSH Test Results
1. High TSH Level
Indicates Hypothyroidism
- Thyroid gland is underactive
- Common causes:
- Hashimoto’s thyroiditis
- Iodine deficiency
- Post-thyroid surgery
2. Low TSH Level
Indicates Hyperthyroidism
- Thyroid gland is overactive
- Common causes:
- Graves’ disease
- Thyroid nodules
- Excess thyroid medication
Sample Type for TSH Test
- Sample Required: Venous Blood
- Volume: 2–3 ml
- Container: Plain vial / Serum separator tube
Sample Collection Guidelines
- Sample is collected from a vein in the arm
- Follow standard aseptic blood collection procedures
- Serum is separated after clotting
- Avoid hemolysis for accurate results
Precautions During Sample Giving
Patients should follow these precautions:
- Inform the lab about thyroid medications
- Avoid stress and heavy exercise before the test
- Take thyroid medicines after blood sample, unless advised otherwise
- Inform if pregnant or having recent illness
Fasting Rules for TSH Test
- Fasting is NOT required some dr recommanded for fasting condition.
- Test can be done at any time of the day
- Morning sample is preferred for consistency
Home Sample Collection
✔️ Available
✔️ Safe and hygienic
✔️ Suitable for elderly, pregnant women, and working individuals
FAQs & Patient Help
1. Is TSH test enough to diagnose thyroid disease?
TSH is the first screening test. Doctors may also advise T3, T4, Free T3, Free T4, or Thyroid Antibodies for confirmation.
2. Can TSH levels change?
Yes, TSH levels can fluctuate due to:
- Stress
- Pregnancy
- Illness
- Medications
3. How often should TSH be tested?
- Every 6–12 months for stable patients
- As advised by doctor during treatment changes
4. Is the test painful?
Only mild discomfort during blood collection.
When Should You Consult a Doctor?
- Abnormal TSH results
- Persistent symptoms despite normal values
- During pregnancy planning or early pregnancy
Trusted Medical Sources
- American Thyroid Association (ATA)
- Mayo Clinic – Thyroid Function Tests
- National Institutes of Health (NIH)
- Indian Thyroid Society (ITS)
- Harrison’s Principles of Internal Medicine
