Assays

By Nelson Vergel — chemical engineer, patient advocate, and 34+ years on TRT | Last updated: July 2026 You feel flat. Training that used to feel easy now drags. You're sleeping enough, your testosterone looks dialed in, and your doctor says your bloodwork is "normal." So why the fatigue? For a...

I have been hammering this home on the forum over the years! Again the only way to know where your FT truly sits is to have it tested using the most accurate assay the gold standard Equilibrium Dialysis especially in cases of altered SHBG! * This case highlights a critical diagnostic pitfall...

https://endo2026.endocrine.org/searchGlobal.asp Background Exogenous estradiol (E2) may be prescribed for transgender females and menopausal women. Automated E2 immunoassays are widely used but bias often exists when compared to mass spectrometry (LC-MS) methods. Lack of assay...

Sit and dwell on that! Think of all those overmedicated men on T-therapy gassed up on FT well beyond their natty genetic set-point and unfortunately many off them off the hop! You can blame all those run of the mill T clinics, kiddie forums loaded with all those numbskulls, throw those blast n...

* The CDC Hormone Standardization Program for Total Testosterone (HoSt-TT) evaluates assay performance against ID-LC-MS/MS using clinically relevant concentrations. * The TSTII assay is CDC HoSt-TT certified, has strong alignment to LC-MS/MS, and shows good correlation of calculated FT with...

* The lack of standardization and harmonization among ferritin assays results in significant variability in clinical values. These assays have different reference ranges and numerous clinical cut-offs for interpreting anemia and iron toxicity. This inconsistency is due to manufacturers using...

https://thebms.org.uk/wp-content/uploads/2025/07/24-NEW-BMS-ToolsforClinicians-Measurement-of-serum-estradiol-JULY2025-B.pdf Summary In summary, it is easy to reach for a blood test when HRT is not perceived to be adequately managing symptoms of the menopause transition. Before an...

ASSESSMENT OF MALE ANDROGEN STATUS: A SURVEY ON MEASUREMENT AND REPORTING OF TOTAL TESTOSTERONE, SEX HORMONE-BINDING GLOBULIN AND FREE TESTOSTERONE IN CLINICAL LABORATORIES ACROSS EUROPE N.Narinx, J. A. Nyamaah, K. David, V. Sommers, J. Walravens, T. Fiers, B. Lapauw, B. Decallonne, F...

https://myadlm.org/advocacy-and-outreach/optimal-testing-guide-to-lab-test-utilization/a-f/estradiol-testing-in-men Estradiol in Men: Optimal Testing Recommendations Measurement of estradiol in men (and children) should be performed by a sensitive liquid chromatography-tandem mass...

https://chronicdisease.org/2024-partnership-for-the-accurate-testing-of-hormones-path-annual-committee-meeting/ On April 25, 2024, the Division of Laboratory Sciences (DLS) Clinical Standardization Programs (CSP) team in the Clinical Chemistry Branch participated in the 2024 Partnership for...

* harmonized reference ranges for total and calculated free testosterone in adults using the Siemens Atellica immunoassay, validated against a reference method. * Reference intervals were adopted from the reference laboratory and verified using 20 male and 20 female healthy samples. *...

Just to be clear! *FT (test code 36170) is calculated by equilibrium dialysis using a modified Vermeulen equation https://testdirectory.questdiagnostics.com/test/test-detail/36170/testosterone-free-dialysis-and-total-ms?cc=MASTER Quest Diagnostics offers the following measurements: TT...

For many years, virtually the only means of studying androgen metabolism in experimental animals or in human subjects was by examination of the urinary steroid metabolites which were presumed to originate from gonadal and adrenocortical androgens. Nevertheless, even though the techniques of...

Hi all. Was wondering which is more "important". Free testosterone or total. I had my annual bloodwork done required by my provider in November of last year. Total testosterone was 1100 ng/dl. Free test was 20.8 pg/mL. E2 was 34 pg/mL. SHBG was 36 nmol/L. I was injecting IM. I switched...

https://academic.oup.com/clinchem/advance-article-abstract/doi/10.1093/clinchem/hvad177/7337000?redirectedFrom=fulltext To the Editor: Testosterone (T) binds to sex hormone-binding globulin (SHBG)and albumin (Alb) to form SHBG-T and Alb-T (1). If total testosterone (TT) is low or SHBG...

BACKGROUND Testosterone is an anabolic steroid produced primarily in the testicles of males and mainly in the ovaries of females. The imbalance of testosterone is the primary cause of hypogonadism in males, hirsutism and virilization in females, osteoporosis, and diabetes mellitus. Accurate and...

High-quality disease biomarker tests are critical for the correct diagnosis and treatment of patients, accurate interpretation of research data, and effective use of research findings in health care. CDC’s Clinical Standardization Program (CDC CSP) assists researchers and laboratories with...

Abstract Objectives: In laboratory medicine, external quality assessment (EQA) schemes have become versatile tools for detecting analytical flaws. However, EQA schemes are lacking for pediatric sex steroid levels. We aimed to investigate the suitability of different estradiol and testosterone...

Only at Excel, are we gonna take you deep! Clinical Utility and Analytical Aspects of Direct Measurements of Free Hormones Using Mass Spectrometry-Based Methods (2022) Mark M. Kushnir, Heather A. Nelson, and Kelly Doyle Background The free hormone (FH) hypothesis states that hormone...

Newly Observed Interference of Oral Biotin with the Free Testosterone Assay? In a Woman with Postmenopausal Virilization (2022) Rafael Caputi, MD and Alejandro Ayala, MD Introduction Approximately 15-20% of US adults take supraphysiologic doses of biotin-containing supplements for common hair...

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