Thyroid Function Test

A thyroid function test measures TSH (thyroid-stimulating hormone), T3, and T4 levels in your blood to determine whether your thyroid gland is working correctly—with an underactive thyroid affecting 1 in 50 women and 1 in 1,000 men in the UK. Symptoms like fatigue, weight changes, and mood issues are often caused by thyroid imbalance that's easily detected with a simple blood test.

At Blood Test London, comprehensive thyroid testing costs from £245 with results in 2-3 days.

What Does a Thyroid Test Measure?

TSH (Thyroid-Stimulating Hormone)

The most important marker. TSH is produced by your pituitary gland to tell your thyroid how much hormone to make.

Normal range: 0.4-4.0 mIU/L (though optimal is often 0.5-2.5)

Free T4 (Thyroxine)

The main hormone produced by your thyroid. "Free" means the active portion not bound to proteins.

Normal range: 12-22 pmol/L

Free T3 (Triiodothyronine)

The active thyroid hormone that affects metabolism. T4 converts to T3 in your body.

Normal range: 3.1-6.8 pmol/L

Thyroid Antibodies (Advanced Testing)

• TPO Antibodies: Indicate Hashimoto's thyroiditis (autoimmune hypothyroidism)

• TSI Antibodies: Indicate Graves' disease (autoimmune hyperthyroidism)

Book Your Thyroid Test via WhatsApp

Signs You Need a Thyroid Test

Underactive Thyroid (Hypothyroidism) Symptoms

• Fatigue and low energy

• Weight gain despite normal eating

• Feeling cold all the time

• Dry skin and hair

• Constipation

• Depression or low mood

• Brain fog and poor concentration

• Heavy or irregular periods

• Muscle aches

Overactive Thyroid (Hyperthyroidism) Symptoms

• Weight loss despite eating more

• Rapid heartbeat or palpitations

• Anxiety and nervousness

• Trembling hands

• Feeling hot and sweating

• Difficulty sleeping

• Frequent bowel movements

• Light or missed periods

Understanding Your Thyroid Results

Hypothyroidism Pattern

• TSH: Elevated (>4.0 mIU/L)

• Free T4: Low or low-normal

• Free T3: Low or low-normal

Hyperthyroidism Pattern

• TSH: Suppressed (<0.4 mIU/L)

• Free T4: Elevated

• Free T3: Elevated

Subclinical Thyroid Disease

• Subclinical hypothyroidism: TSH elevated, T4/T3 normal (may benefit from treatment)

• Subclinical hyperthyroidism: TSH low, T4/T3 normal (monitor closely)

How to Optimise Thyroid Function

Nutrients for Thyroid Health

Lifestyle Factors

• Manage stress: Chronic stress affects thyroid function

• Quality sleep: 7-9 hours nightly

• Avoid excessive goitrogens: Raw cruciferous vegetables in moderation if hypothyroid

• Regular exercise: Supports metabolism and hormone balance

When Medication Is Needed

• Hypothyroidism: Levothyroxine (thyroid hormone replacement)

• Hyperthyroidism: Anti-thyroid medication, radioactive iodine, or surgery

Get Your Thyroid Checked Today

Our Thyroid Test Options

Basic Thyroid (TSH only) - £245

Best for: Screening if you have no symptoms

Standard Thyroid (TSH, T4, T3) - £275

Best for: Comprehensive assessment

Advanced Thyroid (TSH, T4, T3, Antibodies) - £325

Best for: Autoimmune thyroid investigation, family history

Book Your Thyroid Test

Book via WhatsApp

Price: From £245

Results: 2-3 days

Doctor review: A doctor always reviews every result

Fasting required: No (morning test preferred)

FAQ

How common are thyroid problems?
Very common—affecting approximately 1 in 20 people in the UK, with women 5-10 times more likely than men.

Can thyroid problems be cured?
Hypothyroidism is easily managed with daily medication. Hyperthyroidism may be cured with treatment.

How often should I test my thyroid?
Annually if you have risk factors; every 6-8 weeks if adjusting medication; otherwise when symptomatic.

Does thyroid affect weight?
Yes. Underactive thyroid slows metabolism (weight gain); overactive speeds it up (weight loss).

Can stress affect thyroid results?
Yes. Chronic stress can affect thyroid function and should be considered when interpreting results.

Blood Test London by The Wellness. Comprehensive thyroid testing from £245, results in 2-3 days.