Value of Free Thyroxine Index

James V. Felicetta, William L. Green, David S. Cooper, E. Chester Ridgway, Farahe Maloof

Research output: Contribution to journalLetterpeer-review

2 Scopus citations


To the Editor: We wish to point out an error in the tabulation of normal reference laboratory values recently published in the Case Records of the Massachusetts General Hospital.1 The normal range for the free thyroxine index (fT4I) is given as 1 to 4 ng per 100 ml, and the method of Sarin and Anderson2 is cited. However, Sarin and Anderson calculated the fT4I as the product of the serum thyroxine (T4) and the triiodothyronine (T3) resin-uptake ratio, the latter being the ratio of the observed T3 resin uptake to a.

Original languageEnglish (US)
Pages (from-to)1480-1481
Number of pages2
JournalNew England Journal of Medicine
Issue number26
StatePublished - Jun 26 1980
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)


Dive into the research topics of 'Value of Free Thyroxine Index'. Together they form a unique fingerprint.

Cite this