Appropriate Ordering of Free T3 & T4, How Do We Compare to Other Centres, What’s Our Data Telling Us?

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Appropriate Ordering of Free T3 & T4, How Do We Compare to Other Centres, What’s Our Data Telling Us?


While measures of free T4 (fT4) and free T3 (fT3) have replaced previous measurements of total T4 and total T3 levels, they are only indicated in certain clinical instances.

At Women’s College Hospital (WCH) in Toronto, 65% of fT4 and 59% of fT3 measurements were ordered in the setting of a normal TSH. This high proportion of “unnecessary” free thyroid hormone tests inspired the creation of a resource stewardship intervention aimed at reducing fT4/fT3 testing by 50% to promote high-value care.

Firstly, an educational program was rolled-out to engage and inform health care professionals of appropriate indications for free thyroid hormone testing. Secondly, a laboratory reflex-fT4 system was implemented, in which fT4 was only processed if the TSH was outside of the laboratory reference range or clinical justification was provided on the laboratory requisition; fT3 was only processed if justification was provided. Overall, free thyroid hormone testing was reduced by 54%, which was sustained over 6 months. The hospital has benefited from significant cost-savings, physician satisfaction has been high, and patient outcomes have not been adversely affected. The successes of this project have led to its expansion to other institutions in Toronto, including St. Michael’s Hospital (SMH) and University Health Network (UHN).

The Less is More with T3 & T4 toolkit contains the key ingredients of their approach.

Laboratory data for clinicians in Regina and surrounding areas also indicate that fT3 and fT4 tests are being used inappropriately within our local area, exemplified by high volume use by some practitioners.

Continued investigation into the fT3 and fT4 usage data which was shared last month in the Physician’s Newsletter has allowed for further breakdown of the groups to identify those who are deemed to be high users based on their annual number of tests ordered. While the majority of clinicians order none or only a few (1-5) of these tests each year (80% for fT3 and 60% for fT4), the remaining groups are likely to be using some or many of these tests unnecessarily. For example, the Area Division Lead for Endocrinology, Dr. Jeremy Fitzgerald, ordered 42 fT3 tests and 235 fT4 tests in 2016. While it is important to recognize the needs of individual patients in a clinician’s practice when determining appropriate use of these tests, it is likely that clinicians ordering more than this are doing so unnecessarily. There is significant variation in practice, zero to 1,968 tests for primary care physicians.

We will be contacting clinicians determined to be high users to better understand the rational for the utilization of these tests. As well, the group of clinicians that do not utilize will be contacted for the purpose of understanding of how they manage and monitor their patients.

Submitted by Robert Parker, Program Manager, Antimicrobial & Clinical Stewardship