Triiodothyronine, Serum

Optimal Result: 2 - 4.4 pg/mL, or 1.3 - 2.86 nmol/L.

From Healthmatters.io Team

Lab Results Explained and Tracked

Triiodothyronine (T3) is the most biologically active thyroid hormone in humans. It is sometimes called total triiodothyronine because it includes both free triiodothyronine and triiodothyronine bound to proteins. Triiodothyronine acts on almost every cell in the body, binding to thyroid hormone receptors and setting the metabolic rate of cells. Triiodothyronine is critically important for the growth and development of fetuses, infants, and young children. While the thyroid gland produces triiodothyronine, about 80% is created from the other active thyroid hormone, thyroxine. More than 99% of triiodothyronine is bound to proteins in the serum, the rest is free triiodothyronine (free T3).

Normal Ranges for Total T3:

Adult (> or =20 years): 80-200 ng/dL
0-5 days: 73-288 ng/dL
6 days-2 months: 80-275 ng/dL
3-11 months: 86-265 ng/dL
1-5 years: 92-248 ng/dL
6-10 years: 93-231 ng/dL
11-19 years: 91-218 ng/dL

Sources:

http://www.ncbi.nlm.nih.gov/books/NBK285568/

http://www.uptodate.com/contents/laboratory-assessment-of-thyroid-function

http://www.ncbi.nlm.nih.gov/pubmed/12625976

https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8613

http://dx.doi.org/10.1001/jama.1990.03440110095035

http://www.uptodate.com/contents/thyroid-function-in-nonthyroidal-illness

http://www.ncbi.nlm.nih.gov/pubmed?term=7920008

http://www.ncbi.nlm.nih.gov/pubmed/6687730

http://www.uptodate.com/contents/overview-of-thyroid-disease-in-pregnancy

http://www.uptodate.com/contents/diagnosis-of-and-screening-for-hypothyroidism-in-nonpregnant-adults

https://www.uptodate.com/contents/diagnosis-of-hyperthyroidism

http://www.uptodate.com/contents/thyroid-hormone-synthesis-and-physiolog

Lab Results Explained and Tracked

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What does it mean if your Triiodothyronine, Serum result is too high?

Elevated triiodothyronine levels may indicate hyperthyroidism, thyroid hormone resistance syndrome, or triiodothyronine toxicosis. Serum triiodothyronine levels can be expected to increase during normal pregnancy, but other tests may be necessary to rule out hyperthyroidism. Elevated triiodothyronine may cause symptoms of hyperthyroidism including excessive appetite, anxiety, heart palpitations, shortness of breath, sweating, weight loss, emotional disturbances, and intolerance to heat.

Some specific causes of high triiodothyronine are:

Hyperthyroidism
Euthyroid hyperthyroxinemia
Triiodothyronine toxicosis
Acute thyroiditis
Pregnancy
Familial dysalbuminemic hyperthyroxinemia
Drugs that increase TBG (e.g. estrogens, tamoxifen, opioids)
Synthetic triiodothyronine treatment

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What does it mean if your Triiodothyronine, Serum result is too low?

Decreased triiodothyronine levels in the serum usually indicate hypothyroidism or chronic or subacute thyroiditis. Any serious illness can decrease triiodothyronine levels. Abnormally low triiodothyronine may cause symptoms of hypothyroidism including weakness and fatigue, cold intolerance, shortness of breath, weight gain, constipation, cognitive problems, dry skin, hoarseness, and swelling (edema).

Some specific causes of low triiodothyronine are:

Hypothyroidism
Chronic thyroiditis
Subacute thyroiditis
Nephrotic syndrome
Drugs that decrease TBG (e.g. anabolic steroids, glucocorticoids)

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Triiodothyronine, Serum

All Your Lab Results. One Simple Dashboard.

What does it mean if your Triiodothyronine, Serum result is too high?

All Your Lab Results. One Simple Dashboard.

Import, Track, and Share Your Lab Results Easily

Import, Track, and Share Your Lab Results

What does it mean if your Triiodothyronine, Serum result is too low?

Article Review & Sources

Bring All Your Lab Results Together — In One Place

Gather Your Lab History — and Finally Make Sense of It

Finally, Your Lab Results Organized and Clear

Advanced Plan

Unlimited Account

Pro Monthly

What's included in a Healthmatters membership

Import Lab Results from Any Source

See Your Health Timeline

Understand What Your Results Mean

Enter Your Lab Reports Yourself — Always Free Enter Your Lab Reports — Always Free

Visualize Your Results

Export Your Complete Lab History in a Single File Export Your Complete Lab History

Comprehensive Data Entry Service for Your Reports Data Entry Service for Your Reports

Securely Share With Anyone You Trust

Let Your Lab Results Tell the Full Story

Once your results are in one place, see the bigger picture — track trends over time, compare data side by side, export your full history, and share securely with anyone you trust.

Bring all your results together to compare, track progress, export your history, and share securely.

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All Your Lab Results.
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