Thyroid Report Reader | Understand TSH, Free T4 & Free T3

Q: Can I use this tool with only TSH?

Yes. The tool gives a basic TSH-based interpretation. However, Free T4 is needed to separate overt and subclinical patterns.

Enter Your Thyroid Test Values

TSH is commonly used as the first test for thyroid function. Free T4 and Free T3 help give a more complete thyroid pattern when available.

TSH (mIU/L)

TSH — Required

Free T4 Optional

Free T4 — Optional

Free T3 Optional

Free T3 — Optional

Different laboratories may use different reference ranges. If your report shows a reference range, enter it here for a more personalised interpretation. Otherwise, standard reference values will be used.

TSH (mIU/L)

TSH Lower Limit

TSH Upper Limit

Free T4 Limits (ng/dL)

Free T4 Lower Limit

Free T4 Upper Limit

Free T3 Limits (pg/mL)

Free T3 Lower Limit

Free T3 Upper Limit

Thyroid Pattern

What This May Mean

Component Results

Possible Explanations

Abnormal thyroid test patterns may be seen with:

Primary hypothyroidism
Subclinical hypothyroidism
Hyperthyroidism or thyrotoxicosis
Subclinical hyperthyroidism
Thyroiditis
Graves' disease
Thyroid nodules
Pituitary-related thyroid disorders
Pregnancy-related changes
Severe non-thyroid illness
Medication effects
Biotin supplement interference
Laboratory assay interference

This tool cannot identify the exact cause.

Suggested Next Steps

🚨 Seek Urgent Medical Care If Abnormal Thyroid Results Are Associated With:

Chest pain · Severe palpitations · Severe breathlessness · Fainting · Confusion or severe drowsiness · High fever with severe illness · Severe weakness · Pregnancy with abnormal thyroid results

Entered Values

ℹ️ Important

This tool provides educational information only. It cannot diagnose thyroid disease or replace assessment by a qualified healthcare professional. Thyroid test results should be interpreted together with symptoms, medications, pregnancy status and medical history.

This tool provides educational interpretation only. Always consult your doctor for personalised medical guidance.

What Is a Thyroid Function Test?

A thyroid function test is a blood test used to assess how the thyroid gland is working. The most common test is TSH. Free T4 and sometimes Free T3 help provide a more complete picture. These tests do not diagnose one specific cause by themselves, but the pattern of results can guide further assessment.

What Does TSH Mean?

TSH is a hormone released by the pituitary gland to signal the thyroid. A high TSH may occur when the thyroid is underactive. A low TSH may occur when thyroid hormone levels are high. TSH is useful as a first test, but it should be interpreted with Free T4 when available.

What Does Free T4 Mean?

Free T4 is one of the main thyroid hormones circulating in the blood. It helps show whether the body has too much, too little or an expected level of thyroid hormone. When TSH is abnormal, Free T4 helps separate overt from subclinical patterns.

What Does Free T3 Mean?

Free T3 is another thyroid hormone. It is not always needed for routine testing, but it may help in some cases — especially when TSH is low and Free T4 is normal. A raised Free T3 with a low TSH may suggest a T3-predominant thyrotoxic pattern.

Why Can Thyroid Results Be Confusing?

Thyroid results may be affected by medicines, supplements such as biotin, pregnancy, severe illness and laboratory factors. Some patterns also involve the pituitary gland rather than the thyroid gland itself. This is why thyroid results should always be interpreted with the full clinical picture.

When Should You Seek Medical Advice?

Medical advice is important if thyroid results are abnormal, symptoms are significant, pregnancy is present, or results do not match the clinical picture. Urgent care is needed if abnormal thyroid results are associated with chest pain, severe palpitations, breathlessness or confusion.

Related Tools & Resources

Frequently Asked Questions

Common questions about thyroid test results — answered by Sineth Hospitals.

What is the most important thyroid test?▼

TSH is commonly used as the first thyroid test. Free T4 is often added when TSH is abnormal or when a fuller thyroid assessment is needed. Free T3 is not routinely required but may be helpful in specific situations, such as when TSH is low with a normal Free T4.

Can I use this tool with only TSH?▼

Yes. The tool gives a basic TSH-based interpretation when only TSH is entered. However, Free T4 is needed to separate overt hypothyroid or hyperthyroid patterns from subclinical patterns. Adding Free T4 gives a more complete and accurate interpretation.

What does high TSH mean?▼

High TSH may occur when the thyroid gland is underactive. Free T4 helps clarify whether the pattern is overt (TSH high, Free T4 low) or subclinical (TSH high, Free T4 normal). High TSH with symptoms warrants medical assessment.

What does low TSH mean?▼

Low TSH may occur when thyroid hormone levels are high. Free T4 and Free T3 help clarify the pattern. Low TSH with a high Free T4 or Free T3 may suggest a thyrotoxic pattern. Low TSH with normal Free T4 may represent subclinical hyperthyroidism or, occasionally, a T3-predominant pattern.

Can this tool diagnose thyroid disease?▼

No. This tool provides educational interpretation only. Diagnosis requires clinical assessment by a qualified healthcare professional who can consider your symptoms, medical history, examination and other investigations alongside your laboratory results.