Principles and pitfalls of free hormone measurements.
Level 5 - mechanism / opinion, no new human data
Narrative review of laboratory assay principles and reference methods without primary data or systematic search.
PubMed 24094635 · doi:10.1016/j.beem.2013.06.007
What was done
This narrative review outlines the physiological basis (free hormone hypothesis) and analytical challenges of measuring circulating free hormones, using free thyroxine as a primary model. It examines the technical requirements of physical separation methods, mass spectrometry-based reference procedures, and the standardization needs for commercial clinical immunoassays.
What was found
The abstract reports no quantitative results or empirical measurements. It highlights that separating free from protein-bound hormone risks altering the binding equilibrium and requires sensitive quantification of low analyte concentrations. It also emphasizes that mass spectrometry reference methods are necessary to standardize variable commercial immunoassay platforms.
Why it matters
Because free hormone concentrations guide clinical endocrine management, routine laboratory assays must provide accurate and reproducible results. Understanding assay pitfalls and implementing reference-method standardization helps clinicians interpret tests reliably.
Limits
The abstract provides no original quantitative data, sample size, or systematic review methodology. Specific comparative performance metrics among commercially available immunoassays are not detailed.
Cited by
- supports IGF-1 and thyroid hormones circulate bound to specific binding proteins in the body, meaning total circulating hormone levels can appear normal while free, biologically active hormone levels are significantly lower.