LOINC Code 3028-8: T4/Triiodothyronine (T3) uptake index [Mass ratio]

What is this code?

LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Thyroxine/Triiodothyronine uptake index. It is commonly used with the system or sample type Ser/Plas.

When is it used?

• Used in lab systems, EHRs, and clinical data exchange.
• May identify a test, observation, survey item, or clinical document request rather than a diagnosis.
• Status: DISCOURAGED
• Order vs observation: Both

What it does not mean

• The code identifies the observation or test, not the actual result.

Key facts

• Thyroxine (T4)/Triiodothyronine (T3) uptake index [Mass Ratio] in Serum or Plasma
• Thyroxine/Triiodothyronine uptake index
• Chemistry; Endocrine; Endocrinology; Levothyroxine; Levo-thyroxine; L-thyroxine; Mass concentration ratio; Mass ratio; MCRto; Pl; Plasma; Plsm; Point in time; QNT; Quan; Quant; Quantitative; Random; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR; T3; T-3; T3 uptake index; T3U; T3uptake; T4; T-4; thyroid hormone; Thyrox; Thyroxin; Thyrx; Total T3; Total T4; Triodothyrne; TT4

Where you may see this code

You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges.

Common synonyms

Frequently asked questions