LOINC Code 73557-1: Free T4 (BldCo) [Mass/Vol]
73557-1 is a LOINC code used to identify Free T4 (BldCo) [Mass/Vol] in laboratory and clinical observation data. You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges. LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Thyroxine.free. It is commonly used with the system or sample type BldCo.
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.free. It is commonly used with the system or sample type BldCo.
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: ACTIVE
- Order vs observation: Both
What it does not mean
- The code identifies the observation or test, not the actual result.
Key facts
- Thyroxine (T4) free [Mass/volume] in Cord blood
- Thyroxine.free
- In newborn infants, the reference range for free thyroxine varies with gestational age at time of birth, and is also different in cord blood.
- Blood - (umbilical) cord; Chemistry; Cord (umbilical) blood; Cord bld; Cord blood; Endocrine; Endocrinology; FR; FreeT4; FT4; Gyn; Gynecology; Level; Levothyroxine; Levo-thyroxine; L-thyroxine; Mass concentration; Non-protein bound; OB; ObGyn; Obstetrics; Point in time; QNT; Quan; Quant; Quantitative; Random; T4; T-4; T4 Free; thyroid hormone; Thyrox; Thyroxin; Thyrx; Total T4; 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.
Related SNOMED CT concepts
Related observations and tests
Common synonyms
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from LOINC. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.