Serum Leptin (Leptin)
Leptin is a peptide hormone synthesized by white adipose tissue that signals systemic energy sufficiency to hypothalamic POMC/CART neurons to suppress appetite and increase basal thermogenesis.
Standard vs. Optimal Reference Rangesng/mL
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.
0.5 - 13.8 ng/mL (Male), 1.1 - 27.5 ng/mL (Female)
General reference distribution across unselected commercial populations.
2.0 - 6.0 ng/mL
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Binds the LepRb receptor in the arcuate nucleus, activating JAK2-STAT3 signaling. In obesity, chronic hyperleptinemia induces SOCS3 feedback inhibition, causing central leptin resistance.
Differential Diagnosis
Elevated Levels (Leptin High)
- •Adipose hypertrophy / Central leptin resistance
- •Severe obesity
- •Chronic low-grade inflammation
Low Levels (Leptin Low)
- •Congenital leptin deficiency (rare)
- •Severe lipodystrophy
- •Extreme leanness / Caloric restriction
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
Strict 10 to 12 hour overnight water-only fasting is mandatory for baseline metabolic quantification. Acute psychological stress, acute infectious illness, and sleep deprivation (<6 hours) transiently elevate cortisol and catecholamines, falsely elevating glycemic markers. For glucose and insulin testing, draw blood into sodium fluoride/potassium oxalate tubes or separate serum promptly within 30 minutes to prevent ongoing in vitro red blood cell glycolysis.
Reflexive Testing Protocol:
- Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and HOMA-Beta calculations
- Continuous Glucose Monitoring (CGM) 14-day wear to evaluate glycemic variability and postprandial excursions
- Fasting C-Peptide and high-sensitivity Troponin/hs-CRP to differentiate insulin resistance from beta-cell exhaustion
- Oral Glucose Tolerance Test (OGTT) with simultaneous 0, 30, 60, and 120-minute insulin assays
- Abdominal ultrasound or FibroScan to evaluate hepatic steatosis and non-alcoholic fatty liver disease (MASLD)
Clinical Citations & Primary Literature (1)
- [1]Leptin Signaling in Energy Homeostasis and Neuroendocrine Function - Cell Metabolism (2021). PMID: 34183819
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Serum Leptin (Leptin) into overall healthspan optimization.