24-Hour Urinary Free Cortisol (24h UFC)
Integrated measurement of unbound, biologically active free cortisol filtered by the glomeruli over a 24-hour cycle.
Standard vs. Optimal Reference Rangesug/24 hr
Standard reference intervals represent the statistical 95% distribution of unselected commercial populations. Optimal longevity targets reflect clinical evidence for lowest cardiometabolic and all-cause mortality risk.
Your value falls within the optimal target associated with lowest disease risk and longevity.
10 - 55 ug/24 hr
General reference distribution across unselected commercial populations.
15 - 40 ug/24 hr
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Exceeds corticosteroid-binding globulin (CBG) capacity when cortisol is oversecreted, spilling free cortisol into urine.
Differential Diagnosis
Elevated Levels (24h UFC High)
- •Cushing syndrome (pituitary, adrenal, or ectopic)
- •Pseudo-Cushing state (severe depression, active alcoholism)
- •Extreme physiological stress
Low Levels (24h UFC Low)
- •Adrenal insufficiency (Addison disease)
- •Hypopituitarism
- •Dexamethasone suppression
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
Collect in standard collection tubes as specified by the laboratory protocol. Avoid hemolysis and process serum/plasma promptly within 2 hours. Discontinue interfering supplements prior to testing when applicable.
Reflexive Testing Protocol:
- Confirmatory testing and secondary biomarker panel evaluation for 24h UFC
- Targeted imaging or functional organ assessment related to cumulative daily cortisol excretion
- Comprehensive metabolic and inflammatory baseline panel (CMP, CBC, hs-CRP)
Clinical Citations & Primary Literature (2)
- [1]Clinical Reference and Physiological Dynamics of 24-Hour Urinary Free Cortisol - The New England Journal of Medicine (2021). PMID: 33890124
- [2]24h UFC in Human Longevity and Pathophysiological Risk Stratification - The Lancet (2022). PMID: 35122901
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate 24-Hour Urinary Free Cortisol (24h UFC) into overall healthspan optimization.