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T4 (Thyroxine), Total
Quest Diagnostics1 test optionFrom $10.21
T4 (Thyroxine), Total
Quest DiagnosticsCatalog information reviewed: August 24, 2026 by the Sunridge Medical clinical team.
What this laboratory test evaluates
DetailsT4 (Thyroxine), Total – This test is crucial for diagnosing thyroid conditions such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). By measuring the total level of thyroxine (T4) in the blood, it helps in understanding thyroid function and identifying potential issues.
What patients is this test right for?This test is typically ordered for individuals showing symptoms of thyroid dysfunction.
Symptoms of Hypothyroidism:• Fatigue
• Weight gain
• Cold intolerance
• Dry skin
• Constipation
• Depression
Symptoms of Hyperthyroidism:• Weight loss
• Heat intolerance
• Nervousness
• Insomnia
• Hand tremors
• Irregular heartbeat
What type of sample is required for this test?1 mL serum. A simple blood draw is needed.
Additional test information
This test is crucial for diagnosing thyroid conditions such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). By measuring the total level of thyroxine (T4) in the blood, it helps in understanding thyroid function and identifying potential issues.
Collection and processing
- Sample type: Serum
- Fasting: No
- Estimated laboratory processing: Results should be available in 2 – 5 business days after the sample is collected
How Sunridge uses laboratory information
Sunridge considers the medical question, symptoms, history, medications, prior results, and whether the finding could change care before recommending testing. A laboratory result is not interpreted in isolation and does not establish a diagnosis by itself.
Before requesting this test
Availability, collection requirements, eligibility, and processing estimates can change. Sunridge reviews each request and, when appropriate, creates the order through Fullscript. Follow the current instructions supplied with the approved order.
Common questions about this laboratory test
- What sample does this test require?
- The listed sample type is Serum. Confirm current collection instructions in the approved order.
- Does this test require fasting?
- The current catalog record lists fasting as: No. Follow the instructions supplied with the approved order.
- How long does laboratory processing usually take?
- Results should be available in 2 – 5 business days after the sample is collected. Timing can change after collection or if a laboratory requires additional review.
About this test
DetailsT4 (Thyroxine), Total - This test is crucial for diagnosing thyroid conditions such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). By measuring the total level of thyroxine (T4) in the blood, it helps in understanding thyroid function and identifying potential issues.
What patients is this test right for?This test is typically ordered for individuals showing symptoms of thyroid dysfunction.
Symptoms of Hypothyroidism:• Fatigue
• Weight gain
• Cold intolerance
• Dry skin
• Constipation
• Depression
Symptoms of Hyperthyroidism:• Weight loss
• Heat intolerance
• Nervousness
• Insomnia
• Hand tremors
• Irregular heartbeat
What type of sample is required for this test?1 mL serum. A simple blood draw is needed.
Additional details
This test is crucial for diagnosing thyroid conditions such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). By measuring the total level of thyroxine (T4) in the blood, it helps in understanding thyroid function and identifying potential issues.
Highlighted health areas
- Metabolic function
- Women's health
- Hormones
- Thyroid
- Men's health
Biomarkers and report focus
The exact analytes and report format can change. Confirm the current contents in the Fullscript order before payment.
- Free T4 Index (T7)
- T4 (Thyroxine), Total