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