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Quest Diagnostics Test Code: 859

Total T3 measurements are used to diagnose and monitor treatment of hyperthyroidism and are essential for recognizing T3 toxicosis.

T3, also known as triiodothyronine, is a hormone that is released from the thyroid gland. Together with the hormone T4, they help to regulate body metabolism and energy expenditure rate. T3 is released into the bloodstream from the thyroid gland and travels to its target organs while being bound to plasma proteins. When T3 is bound to plasma proteins, it is in its inactive form. The total measurement of T3 in the blood is measured by the amount of free T3 plus bound T3. This test is performed as a marker of thyroid function, for diseases like hyper and hypothyroidism..

This test is performed in following conditions such as:

Signs and symptoms of hyperthyroidism
• Weight loss
• Increased heart rate
• Anxiety
• Difficulty sleeping
Signs and symptoms of hypothyroidism
• Weight gain
• Dry skin
• Constipation
• Cold intolerance

Also Known As: T3 Total, Triiodothyronine (T3)


Specimen Collected
  • Blood
Estimated Time Taken

Turnaround time for the T3 test is typically 1 business day.