Triiodothyronine, Total and Free


T3 and FT3.

To assist in evaluating thyroid function primarily related to diagnosing hyperthyroidism and monitoring the effectiveness of therapeutic interventions.

Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings
Method: Electrochemiluminescent Immunoassay.

AgeConventional UnitsSI Units (Conventional Units × 0.0154)
Cord blood14–86 ng/dL0.22–1.32 nmol/L
1–3 days100–292 ng/dL1.54–4.5 nmol/L
4–30 days62–243 ng/dL0.96–3.74 nmol/L
1–12 mo105–245 ng/dL1.62–3.77 nmol/L
1–5 yr105–269 ng/dL1.62–4.14 nmol/L
6–10 yr94–241 ng/dL1.45–3.71 nmol/L
16–20 yr80–210 ng/dL1.23–3.23 nmol/L
Adult70–204 ng/dL1.08–3.14 nmol/L
Older adult40–181 ng/dL0.62–2.79 nmol/L
Pregnant woman (last 4 mo gestation)116–247 ng/dL1.79–3.8 nmol/L
AgeConventional UnitsSI Units (Conventional Units × 1.54)
0–3 days2–7.9 pg/mL3.1–12.2 pmol/L
4–30 days2–5.2 pg/mL3.1–8 pmol/L
1–23 mo1.6–6.4 pg/mL2.5–9.9 pmol/L
2–6 yr2–6 pg/mL3.1–9.2 pmol/L
7–17 yr2.9–5.1 pg/mL4.5–7.8 pmol/L
Adults and older adults2.4–4.2 pg/mL3.7–6.5 pmol/L
Pregnant women (4–9 mo gestation)2–3.4 pg/mL3.1–5.2 pmol/L

Critical Findings and Potential Interventions

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