Serum Thyroxine Resin Uptake of Liothyronine I 125, and Free Thyroxine Index

Raj K. Sarin, MD; Bernhard G. Anderson, MD
Arch Intern Med. 1970;126(4):631-634. doi:10.1001/archinte.1970.00310100077008.
Text Size: A A A
Published online

Thyroxine (T4) in serum was determined by competitive protein-binding analysis, the resin uptake of liothyronine I 125 (RT3) was measured, and a "free T4 index" was calculated as the mathematical product of values for T4 iodine (T4I) and RT3. Pregnant euthyroid patients and normal women taking estrogens had high values for T4I associated with low values for RT3. Sick euthyroid patients tended to have decreased values for T4I with high values for RT3. The free T4 index accurately reflected the state of thyroid function in euthyroid patients with disturbances of T4-binding proteins, as well as in patients with hyperthyroidism or hypothyroidism.


Sign In to Access Full Content

Don't have Access?

Register and get free email Table of Contents alerts, saved searches, PowerPoint downloads, CME quizzes, and more

Subscribe for full-text access to content from 1998 forward and a host of useful features

Activate your current subscription (AMA members and current subscribers)

Purchase Online Access to this article for 24 hours





Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).
Submit a Comment


Some tools below are only available to our subscribers or users with an online account.

Sign In to Access Full Content

Related Content

Customize your page view by dragging & repositioning the boxes below.