Thyroid Function

Total Triiodothyronine (Total T3)

Normal range 80–200 ng/dL (1.2–3.1 nmol/L SI). Specimen: Serum.

Also known as: T3.

80–200 ng/dLReference range

Reference range

Conventionalng/dL

80200

SInmol/L

1.23.1

Specimen	Serum
Conventional range	80–200 ng/dL
SI range	1.2–3.1 nmol/L
Conversion factor	×0.0154 (conventional → SI)
Panel	Thyroid Function

Convert any Total Triiodothyronine (Total T3) result between units on the unit converter.

What is the normal range for Total Triiodothyronine (Total T3)?

The standard teaching reference range for Total Triiodothyronine (Total T3) is 80–200 ng/dL in conventional units, or 1.2–3.1 nmol/L in SI units. This value is measured in serum.

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population — always use the range printed on the actual result.

Above the range

Common causes of a high Total Triiodothyronine (Total T3)

Hyperthyroidism
T3 thyrotoxicosis

Below the range

Common causes of a low Total Triiodothyronine (Total T3)

Hypothyroidism
Non-thyroidal illness

At the bedside

Nursing considerations

Falls in serious non-thyroidal illness (low-T3 syndrome).

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Free Thyroxine (Free T4)0.8–1.8 ng/dL Free Triiodothyronine (Free T3)2.3–4.2 pg/mL Thyroid Peroxidase Antibody (TPO Ab)< 35 (negative) IU/mL Thyroid-Stimulating Hormone (TSH)0.4–4 mIU/L Total Thyroxine (Total T4)5–12 µg/dL