A Critical Evaluation of Simple Methods for the Estimation of Free Testosterone in Serum

Clicks: 1
ID: 289831
1999
Free PDF
Article Quality & Performance Metrics
Overall Quality
Not rated
Combines reader engagement with the AI quality analysis. This article has not been analysed, so there is no overall score — reader engagement is measured and shown alongside.
AI Quality Assessment
Not analyzed
Readership in this journal

Ranked #251 of 362 articles by views in the journal of clinical endocrinology & metabolism

Most read Least read

Bar heights use a square-root scale. Only the 120 most-read articles are drawn; the journal has 362 in total.

Mint this article as an NFT
Not yet minted

Create a permanent, verifiable on-chain record of this article on the Scimatic Network. The NFT is held in your Journament account, and you can withdraw it to your own wallet at any time.

5 SUSD one-off · no wallet required
Sign in to mint
Abstract
Abstract The free and nonspecifically bound plasma hormone levels generally reflect the clinical situation more accurately than total plasma hormone levels. Hence, it is important to have reliable indexes of these fractions. The apparent free testosterone (T) concentration obtained by equilibrium dialysis (AFTC) as well as the fraction of serum T not precipitated by 50% ammonium sulfate concentration (non-SHBG-T; SHBG, sex hormone-binding globulin), often referred to as bioavailable T, appear to represent reliable indexes of biologically readily available T, but are not well suited for clinical routine, being too time consuming. Several other parameters have been used without complete validation, however: direct immunoassay of free T with a labeled T analog (aFT), calculation of free T (FT) from total T and immunoassayed SHBG concentrations (iSHBG), and the free androgen index (FAI = the ratio 100T/iSHBG). In the view of substantial discrepancies in the literature concerning the free or bioavailable T levels, we compared AFTC, FT, aFT, FAI, and non-SHBG-T levels in a large number of sera with SHBG capacities varying from low, as in hirsute women, to extremely high as in hyperthyroidism. All these indexes of bioavailable T correlated significantly with the AFTC concentration; AFTC and FT values were almost identical under all conditions studied, except during pregnancy. Values for aFT, however, were only a fraction of either AFTC or FT, the fraction varying as a function of SHBG levels. Also, the FAI/AFTC ratio varied as a function of the SHBG levels, and hence, neither aFT nor FAI is a reliable index of bioavailable T. The FT value, obtained by calculation from T and SHBG as determined by immunoassay, appears to be a rapid, simple, and reliable index of bioavailable T, comparable to AFTC and suitable for clinical routine, except in pregnancy. During pregnancy, estradiol occupies a substantial part of SHBG-binding sites, so that SHBG as determined by immunoassay overestimates the actual binding capacity, which in pregnancy sera results in calculated FT values that are lower than AFTC. The nonspecifically bound T, calculated from FT, correlated highly significantly with and was almost identical to the values of non-SHBG-T obtained by ammonium sulfate precipitation, testifying to the clinical value of FT calculated from iSHBG.
Reference Key
openalex_W2098247759 Use this key to autocite in the manuscript while using SciMatic Manuscript Manager or Thesis Manager
Authors Alex Vermeulen, L. Verdonck, Jean‐Marc Kaufman
Journal the journal of clinical endocrinology & metabolism
Year 1999
DOI
10.1210/jcem.84.10.6079
URL
https://doi.org/10.1210/jcem.84.10.6079
Keywords Keywords not found

Citations

No citations found. To add a citation, contact the admin at info@scimatic.org

Comments

No comments yet. Be the first to comment on this article.