Clinical and laboratory aspects of 3,3',5'-triiodothyronine (reverse T3).
Level 5 - mechanism / opinion, no new human data
Narrative review without systematic search or original empirical data
PubMed 33040575 · doi:10.1177/0004563220969150
What was done
Narrative review describing the biological pathways, laboratory measurement techniques (transitioning from radioimmunoassay to mass spectrometry), and clinical contexts associated with serum reverse T3 (3,3',5'-triiodothyronine).
What was found
No quantitative data or statistical estimates are reported in the abstract. The review states that mass-spectrometry methods reduce cross-reactivity interference compared to competitive radioimmunoassays. Serum rT3 concentrations are noted to rise during non-thyroidal illness syndrome, following administration of medications that inhibit its clearance such as amiodarone, and in genetic disorders impacting iodothyronine deiodinases, thyroid transporters, or transport proteins.
Why it matters
It clarifies the diagnostic role of rT3 as a specialized biochemical fingerprint for specific genetic or systemic alterations in thyroid metabolism, rather than a tool for routine thyroid screening.
Limits
As a narrative review, it presents no original patient data, diagnostic threshold metrics, or systematic search criteria. The clinical significance of extranuclear rT3 binding remains unproven, and standard clinical utility remains restricted.
Cited by
- supports T4 can convert into reverse T3 when a person is under high levels of stress.