The Thyroid Function Test checks how well your thyroid gland is working by measuring three key hormones: TSH, Free T3, and Free T4. These hormones control energy, metabolism, and growth. Abnormal results can explain symptoms like fatigue, weight changes, mood shifts, or temperature sensitivity, and may indicate an underactive or overactive thyroid.
Wondering if your unexplained fatigue, weight changes, mood swings, or temperature sensitivity could be linked to how well your thyroid is regulating your body's metabolism?
Overview
Your thyroid is like your body's master thermostat, controlling how fast or slow your metabolism runs, how much energy you have, and even how warm you feel. The Thyroid Function test measures three key hormones—TSH (the signal from your brain telling your thyroid what to do), T4 (the main hormone your thyroid produces), and T3 (the active form that actually gets things done in your cells)—to see if your internal thermostat is working properly.
When your thyroid is out of balance, it can leave you feeling exhausted, struggling with unexplained weight changes, feeling unusually cold or hot, or just "off" in ways that are hard to describe. This test is particularly valuable if you're experiencing these symptoms, have a family history of thyroid issues, or are already taking thyroid medication and need to make sure your dosage is just right. By getting a clear picture of how your thyroid is performing, you and your healthcare provider can work together to optimize your energy levels and overall well-being.
Reviewed by Dr. Vu Tran Bloody Good’s Chief Medical Officer
Symptoms
You may benefit from this test if you experience:
Feeling tired all the time
Extreme fatigue that doesn't improve with rest
Difficulty getting out of bed in the morning
Always feeling cold even in warm weather
Cold hands and feet even in warm weather
Always feeling hot or overheated
Excessive sweating during normal activities
Hair falling out in clumps
Thinning hair all over scalp
Brittle or weak fingernails
Very dry or flaky skin
Difficulty losing weight despite diet and exercise
Unexplained weight gain
Feeling sad or down most of the time
Feeling restless or agitated
Heart palpitations or racing heart
Irregular periods (cycles shorter than 21 or longer than 35 days)
Waking up tired even after full night's sleep
Feeling like tasks require too much effort
Feeling unrefreshed after sleep
Changes in hair texture
Snoring that disrupts sleep
Weight that fluctuates significantly
Inability to warm up
Sweating with minimal exertion
Intolerance to heat
Family history of thyroid problems
Thyroid medication adjustment
Purpose
Essential for anyone experiencing unexplained fatigue, weight changes, mood disorders, hair loss, temperature sensitivity, or heart palpitations. Particularly important for women over 35, those with family history of thyroid disease, autoimmune conditions, or fertility issues. Valuable for monitoring existing thyroid conditions, medication effectiveness, and routine health screening.
How to prepare
Morning collection before 10 AM recommended for optimal TSH accuracy as levels fluctuate throughout the day. No fasting required. Avoid biotin supplements for 3 days before testing. If taking thyroid medication, maintain your usual schedule unless advised otherwise by your healthcare provider. Inform your doctor about any medications, particularly thyroid hormones, steroids, or biotin supplements.
Understanding results
Normal ranges: TSH 0.5-4.0 mIU/L, Free T4 10-25 pmol/L, Free T3 3.0-6.5 pmol/L. Low TSH with high T4/T3 suggests hyperthyroidism; High TSH with low T4 indicates hypothyroidism; Normal TSH with abnormal T4/T3 may indicate subclinical conditions. Results should be interpreted alongside symptoms and clinical presentation. Optimal ranges may differ from laboratory reference ranges for symptom resolution.
After the test
Discuss results with your healthcare provider, particularly if values are outside normal ranges or if you have persistent symptoms. Abnormal results may require additional testing including thyroid antibodies, ultrasound, or more comprehensive hormone panels. Treatment options range from lifestyle modifications to medication. Follow-up testing typically recommended every 6-12 months for monitoring or 6-8 weeks after medication changes.
Frequently Asked Questions
TFT measures thyroid hormones that control metabolism, energy, and numerous body functions, crucial for diagnosing thyroid disorders.
High levels may indicate hyperthyroidism causing rapid metabolism, while low levels may indicate hypothyroidism causing slow metabolism.
Symptoms may include fatigue, weight changes, temperature sensitivity, heart rate changes, mood changes, and hair or skin problems.
Causes include autoimmune diseases, iodine deficiency, medications, radiation exposure, and genetic factors affecting thyroid function.
Treatment may include thyroid hormone replacement for hypothyroidism or anti-thyroid medications for hyperthyroidism, depending on the condition.
Frequency depends on individual risk factors, symptoms, and whether monitoring known thyroid conditions or screening for new problems.
We want you to feel bloody good—inside and out. Regular testing isn’t just about checking your current health; it helps you spot abnormal values you might not know about.
1
Book your referral
Choose the testing that suits your goals. After ordering, you will receive your referral by email.
2
Collect your sample
Easy sample collection at one of our 4000+ partner collection centres throughout Australia. Find nearest
3
Receive your results
View your lab results and receive a personalised review from the secure Bloody Good platform.
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