Biomarker
Klotho (Serum)
Last updated 2026-07-02· Last reviewed 2026-07-02· 1 min read
Reviewed by the Ultimate Longevity Bible editorial team. Educational reference — not medical advice. See disclaimer.
Physiology
- Produced primarily by the kidney; also expressed in brain choroid plexus.
- Regulates phosphate homeostasis (FGF23 co-receptor), vitamin D metabolism, insulin/IGF-1 signalling, and Wnt signalling.
- Circulates as soluble α-Klotho (secreted or shed) at 200–1,500 pg/mL in adults.
Evidence for use as a biomarker
- Declines with age, CKD, and cardiovascular disease.
- Predicts all-cause mortality independent of eGFR in older adults.
- Lower levels associated with cognitive impairment.
Analytical caveats
- ELISA assays vary in what they detect (α-Klotho vs β-Klotho, cleaved vs full).
- Standardisation lags behind research use.
- Not yet available in routine hospital labs.
Actionable implications
None validated. Interventions being explored: exercise (modest elevation), lithium (in animal models), and direct Klotho protein therapy (preclinical).
- Klotho KL-VS Variant — Gene.
- IGF-1 (Insulin-Like Growth Factor 1) — Biomarker.
- MoCA (Montreal Cognitive Assessment) — Biomarker.
- Best Supplements for Longevity (Evidence-Backed Only) — Best-of guide.
- The Blue Zones Solution — Dan Buettner (2015) — Book.