- Physical Examination
- Surgical Examination
- Ophthalmology
- Clinical Skills
- Orthopedics
- Surgery Videos
- Laparoscopy
- Pediatrics
- Funny Videos
- Cardiothoracic Surgery
- Nursing Videos
- Plastic Surgery
- Otorhinolaryngology
- Histology and Histopathology
- Neurosurgery
- Dermatology
- Pediatric Surgery
- Urology
- Dentistry
- Oncology and Cancers
- Anatomy Videos
- Health and Fitness
- Radiology
- Anaesthesia
- Physical Therapy
- Pharmacology
- Interventional Radiology
- Cardiology
- Endocrinology
- Gynecology
- Emergency Medicine
- Psychiatry and Psychology
- Childbirth Videos
- General Medical Videos
- Nephrology
- Physiology
- Diet and Food Health
- Diabetes Mellitus
- Neurology
- Women Health
- Osteoporosis
- Gastroenterology
- Pulmonology
- Hematology
- Rheumatology
- Toxicology
- Nuclear Medicine
- Infectious Diseases
- Vascular Disease
- Reproductive Health
- Burns and Wound Healing
- Kidney Zone Podcast
- Other
Free Triiodothyronine
Abbreviation: Free T3
Panel: Thyroid Tests · All thyroid tests
Typical adult reference range
| Conventional units | 2.3–4.2 pg/mL |
| SI units | 3.5–6.5 pmol/L |
Ranges vary between laboratories and methods — compare your result with the range printed on your own report.
What a high or low result can mean
High free triiodothyronine: high values can be seen in hyperthyroidism.
Low free triiodothyronine: low values may occur in hypothyroidism and in severe non-thyroid illness.
These are associations, not a diagnosis: the same result can have several causes, and your clinician interprets it with the rest of your results and history.
Related tests — Thyroid Tests
Please note: Reference ranges vary between laboratories, and between the methods and instruments they use — the range printed on your own report is the one your result should be compared with. A result outside the range is not by itself a diagnosis, and a result inside it does not rule out illness. These pages are an educational summary, not medical advice: always discuss your results with the clinician who ordered them, who can interpret them in the context of your health and history.