Triiodothyronine

ChemistryAlso known as: T3 24h Ur-mRateAlso known as: T3 24h Ur-sRateAlso known as: T3 Msmt SerPlnmol/L

Measures the active thyroid hormone triiodothyronine (T3) in blood.

Normal Range

Consult your provider

nmol/L

Abnormal Levels

Consult your provider

Specimen Type

Blood

Why This Biomarker Matters

T3 is the most biologically active thyroid hormone, directly influencing metabolism and energy. Abnormal T3 levels can cause fatigue, weight changes, and temperature regulation problems and require prompt evaluation.

Overview

Triiodothyronine (T3) is one of the main thyroid hormones and is the more active form compared to T4. A T3 test measures circulating T3 levels and helps assess thyroid function, particularly in evaluating hyperthyroidism, monitoring thyroid medication, and investigating fatigue or weight changes. T3 affects metabolism, energy production, and body temperature. Low T3 levels may indicate hypothyroidism or a metabolic adaptation, while high T3 suggests overactive thyroid function.

Technical Information (LOINC Codes)

Standardized laboratory codes for this biomarker

3053-6Primary

Triiodothyronine (T3) [Mass/volume] in Serum or Plasma

ng/dL

83125-5

Triiodothyronine (T3) [Moles/volume] in Serum or Plasma by Immunoassay

nmol/mL

26879-7

Triiodothyronine (T3) [Mass/volume] in Saliva (oral fluid)

ng/dL

14930-2

Triiodothyronine (T3) [Moles/volume] in Serum or Plasma

nmol/L

83124-8

Triiodothyronine (T3) [Mass/volume] in Serum or Plasma by Immunoassay

ng/mL

97164-8

Triiodothyronine (T3) [Mass/time] in 24 hour Urine

ug/(24.h)

97165-5

Triiodothyronine (T3) [Moles/time] in 24 hour Urine

mmol/(24.h)

Available Lab Tests

Order tests that measure this biomarker

T3 Free Tracer Dialysis

$268.40

Total T3

$18.76

Results in 1-2 business days