Davis's Lab & Diagnostic Tests

Triiodothyronine, Total

Triiodothyronine, Total is a topic covered in the Davis's Lab & Diagnostic Tests.

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

Serum collected in a gold-, red-, or red/gray-top tube. Plasma collected in a green-top (heparin) tube is also acceptable.

Normal Findings:
(Method: Immunoassay)

AgeConventional UnitsSI Units (Conventional Units × 0.0154)
Cord blood14–86 ng/dL0.22–1.32 nmol/L
1–3 d100–292 ng/dL1.54–4.5 nmol/L
4–30 d62–243 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

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