CDC STANDARDIZED TOTAL T and ESTRADIOL ASSAYS and soon to be FREE TESTOSTERONE!

[madman]

CDC Hormone Standardization Program (CDC HoSt) Certified Estradiol Assays (UPDATED 4/2024)

 

[madman]

Comparability of Free Testosterone Measurements- Results of the Interlaboratory Study

Assessment of free testosterone (FT) has been recommended as a biomarker for diagnosis and management of hypogonadism and female hyperandrogenism. Reliable laboratory measurements are essential for correctly diagnosing and treating these diseases. FT is currently measured using direct commercial...

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[madman]

*The data from the present analyses suggest that the interaction of the three sex hormones with their cognate binding proteins is highly complex and dynamic and influenced by their relative circulating concentrations. Therefore, models of testosterones binding to SHBG, based on the assumption of fixed apparent binding affinity of sex hormones with SHBG, that do not consider the influence of estradiol and dihydrotestosterone on the free testosterone fraction are unlikely to provide accurate estimates of free testosterone fraction.

Modulation of circulating free testosterone fraction by T, DHT and estradiol during TRT

The thread discusses the modulation of circulating free testosterone fraction during Testosterone Replacement Therapy (TRT) and its relationship with other hormones. Here are the main points from the discussion: Free Testosterone Fraction: The thread emphasizes the importance of the free...

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* Collectively, these data highlight the non-linear, concentration-dependent modulation of testosterone repartitioning into bound and free fractions by each of the three sex hormones.

*Our finding that the estradiol, DHT, and testosterone interact to alter free testosterone fraction non-linearly suggests that in men with hypogonadism who are receiving TRT, free testosterone levels should be measured using a reliable method to guide the dose titration. The models that do not consider changes in estradiol and DHT concentrations are susceptible to error in estimating free testosterone concentrations.

*These data suggest that changes in estradiol and dihydrotestosterone concentrations should be considered in evaluating response to testosterone treatment because of their differential influence on free testosterone concentrations in addition to their ability to exert other independent biologic effects. Because of these complex interactions between various sex hormones as well as other ligands with sex hormone binding globulin, direct measurements of free testosterone using a reliable assay, such as the equilibrium dialysis method, may be a superior marker of testosterone’s treatment effect.