T3

Abbreviation with 2 meanings

T3
Stands forTriiodothyronine
Meanings2
CategoriesMedical

T3 has two meanings. It stands for Triiodothyronine (endocrinology & diabetes) or Tylenol with Codeine No. 3 (drug).

Meanings of T3 at a glance

#T3 stands forContext
1TriiodothyronineMedical › Endocrinology & Diabetes
2Tylenol with Codeine No. 3Medical › Drug

1. Triiodothyronine

Medical · Endocrinology & Diabetes Abbreviations

Active form of thyroid hormone, containing three iodine atoms. Most circulating T3 is made in tissues by converting T4, and levels are measured mainly when hyperthyroidism is suspected, since T3 can be high even when T4 is normal.

Example: TSH suppressed, free T4 normal, free T3 elevated: T3 toxicosis from toxic nodule.

Free T3 measures the unbound hormone. T3 is not useful for diagnosing or monitoring hypothyroidism, because levels stay normal until disease is advanced. Liothyronine is synthetic T3, sometimes combined with levothyroxine. Reverse T3, an inactive form, rises in severe illness but has limited clinical value.

2. Tylenol with Codeine No. 3

Medical · Drug Abbreviations

Informal abbreviation for the combination of acetaminophen 300 mg and codeine 30 mg, sold as Tylenol with Codeine No. 3. ISMP lists it as error-prone because T3 is also the standard abbreviation for the thyroid hormone liothyronine.

Example: Patient requests "T3s" for dental pain; discharge Rx written as acetaminophen-codeine 300/30.

Codeine is converted to morphine by CYP2D6, and ultrarapid metabolizers can develop dangerous morphine levels; the FDA contraindicated codeine in children under 12 in 2017. In the US, acetaminophen-codeine tablets are Schedule III. ISMP recommends writing the full generic names and strengths.

More endocrinology & diabetes abbreviations

  • SIADH – Syndrome of inappropriate antidiuretic hormone secretion
  • SMBG – Self-monitoring of blood glucose
  • T1DM – Type 1 diabetes mellitus
  • T2DM – Type 2 diabetes mellitus
  • T4 – Thyroxine
  • Tg – Thyroglobulin
  • TI-RADS – Thyroid Imaging Reporting and Data System
  • TIR – Time in range

See all 64 endocrinology & diabetes abbreviations →

More drug abbreviations

  • SOF – Sofosbuvir
  • SPS – Sodium polystyrene sulfonate
  • SSKI – Saturated solution of potassium iodide
  • SSZ – Sulfasalazine
  • TAC – Tacrolimus
  • TAF – Tenofovir alafenamide
  • TDF – Tenofovir disoproxil fumarate
  • THC – Tetrahydrocannabinol

See all 170 drug abbreviations →

Edited by the AbbreviationList.com team. Spotted an error or a missing meaning? Contact us.

This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.