What is α-Tetrahydrocortisol (α-THF) And Why Does the Hormone Zoomer Test for It?

Cortisol 5α-reduction metabolite

α-Tetrahydrocortisol (α-THF) is a urinary metabolite formed when the body breaks down cortisol via 5α-reduction and subsequent enzymatic steps. Measuring α-THF gives insight into cortisol clearance pathways and enzyme activity that shape stress-hormone turnover.

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α-Tetrahydrocortisol (α-THF)

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About α-Tetrahydrocortisol (α-THF)

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About α-Tetrahydrocortisol (α-THF)

Overview and History

α-THF is a steroid metabolite produced when cortisol undergoes enzymatic reduction (notably 5α-reductase) and further modification before renal excretion. Biochemically, it is classified as a tetrahydro-metabolite of cortisol and is measured in urine as part of steroid metabolite profiling. Historically, urinary tetrahydro-metabolites have been used in research and clinical chemistry to map adrenal output and steroid-processing enzymes. α-THF itself is biologically inactive; its value is as a marker that reflects prior cortisol exposure and the activity of hepatic and peripheral steroid-metabolizing enzymes.

Interpreting Highs and Lows

Higher urinary α-THF can reflect increased cortisol turnover or greater activity of 5α-reductase and related reduction pathways, or a shift in how cortisol is being cleared. Lower α-THF may indicate reduced cortisol metabolism via the 5α-reductase route, lower overall cortisol production, or a shift toward alternative clearance pathways. Interpretation requires comparison with other panel components—salivary cortisol rhythms, total urinary cortisol/cortisone and their metabolites, and enzyme ratio patterns—to distinguish whether differences arise from production, timing, or metabolic routing.

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α-THF is included in the Hormone Zoomer to characterize cortisol metabolism and the activity of specific steroid-transforming enzymes. As part of the panel, it helps separate changes in cortisol production from changes in clearance pathways, enriching the report’s view of stress-hormone timing and metabolic routing to support more precise clinical interpretation.

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α-Tetrahydrocortisol (α-THF) FAQs

What is α-Tetrahydrocortisol (α-THF) and why is it important?

α-THF is a urine marker produced when cortisol is metabolized by reduction enzymes. It doesn’t act as a hormone itself but shows how cortisol was processed and cleared. That information helps clarify patterns of stress-hormone turnover that relate to energy, sleep, and metabolic regulation.

What does it mean if my α-Tetrahydrocortisol (α-THF) levels are low?

Low α-THF suggests less cortisol being processed through the 5α-reduction pathway, which could come from lower cortisol output or from metabolism shifting to other pathways. Alone it’s not definitive; comparing α-THF with total cortisol, cortisone, other metabolites, and diurnal measurements helps determine whether the finding reflects production, timing, or altered enzyme activity.

What does it mean if my α-Tetrahydrocortisol (α-THF) levels are high?

Elevated α-THF may indicate increased cortisol turnover or heightened activity of 5α-reductase and related reduction pathways. High values are best interpreted alongside salivary cortisol patterns, total urinary cortisol/cortisone, and other metabolites to understand whether the pattern reflects greater cortisol exposure, altered clearance, or enzyme shifts.

Why is α-Tetrahydrocortisol measured in the Hormone Zoomer?

Measuring α-THF helps providers distinguish between changes in cortisol production and changes in how the body clears cortisol. Within the Hormone Zoomer’s integrated panel, α-THF adds enzyme- and pathway-level detail that refines interpretation of stress rhythms, metabolic routing, and potential contributors to symptoms.

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