Triiodothyronine
(T3)

Sample type:-

Serum (preferred)

Plasma (lithium heparin)

Uses: -

1. helps diagnose thyroid conditions, specifically hyperthyroidism.

2. Evaluating cases in which FT4 is borderline elevated.

3. Predicting outcome of antithyroid drug therapy in patients with Graves disease.

4. Monitoring T4 replacement therapy—is better than T4 or FT4, but TSH is preferred to both.

Precautions :-

• No special precautions but the doctor may need the patient to stop taking any medicines before the test. Certain medicines can raise or lower T3 levels.

• If a red-top tube or plasma is used, transfer separated serum or plasma to a plastic transport tube.

Interfering factors :-

1) T3 test results are often compared with T4 and TSH test results to help diagnose thyroid disease.

2) If you’re not pregnant or suffering from liver disease, elevated T3 levels might indicate thyroid issues.

3) T3 regulates the body’s metabolism, activates cells, and enables vital organs to function.

4) Variations in TBG and other binding proteins can affect T3. Such increases may be found with use of oral contraceptives, pregnancy, and other binding protein abnormalities. Fasting causes T3 and TSH to decrease.

5) Values below the lower limit of the expected value range can be caused by a number of conditions, including nonthyroidal illness, acute and chronic stress, and hypothyroidism.

Pre analytical errors:-

1. Citrate plasma specimen ,Unlabeled or mislabeled specimen .

The Corrective action

• Reject the sample and another one is requested.

Post analytical errors:-

1. Write wrong name on the report.

2. Send wrong results to the patient.

The Corrective action:-

1. make sure that the name and all data are right

2. Communicate to the patient and apologize for this mistake and sent the right report to him.

Reference range:-

Total T3 : 87–178 ng/dL

Free T3 : 2.5–3.9 pg/mL