Dr. Kathleen Léger

Dr. Kathleen Léger is a triple board-certified physician in Internal Medicine, Nephrology, and Critical Care Medicine, bringing exceptional clinical rigor to Extension Health’s personalized longevity and performance-focused care.

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Her background spans some of the most complex environments in medicine, where she has spent over a decade managing multi-system conditions that demand precision, nuance, and data-driven decision-making. This depth of experience allows her to see patterns across organ systems—and intervene earlier, smarter, and more holistically.

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Dr. Léger has a strong clinical focus on women’s health and female hormone optimization, with particular interest in how hormonal shifts influence energy, cognition, metabolic health, cardiovascular risk, and long-term aging trajectories. Her approach integrates evidence-based medicine with emerging insights from functional and preventive care to address root causes rather than isolated symptoms.

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She is completing advanced training in Functional Medicine through the American Academy of Anti-Aging Medicine (A4M) and holds a Nutrition Science certification from Stanford University, reinforcing her systems-based, whole-person approach.

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In addition to her clinical work, Dr. Léger is an active researcher and educator, with peer-reviewed publications, leadership roles in clinical trials, and experience developing physician training curricula. She is also involved in global health education initiatives.

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At Extension Health, Dr. Léger partners closely with patients to translate complex data—labs, biomarkers, imaging, and lifestyle inputs—into clear, actionable strategies that support hormonal balance, resilience, and long-term vitality, particularly for women navigating high-performance lives.