Explore Dr. Retzler’s HormoneSynergy® Longevity Medicine Resource Library

Longevity Medicine, Functional Wellness & Anti-Aging Insights from HormoneSynergy®

Welcome to the HormoneSynergy® Longevity Medicine Blog, a physician-guided clinical library led by Dr. Kathryn Retzler. Our articles cover the systems that most often shape health with age: metabolic health, hormones, cardiovascular and kidney risk, body composition, bone and muscle, brain health, sleep, gut health, nutrition, supplements, and the biology of aging.

The library is organized around clinical questions rather than trends. Some articles review new research. Others explain testing, treatment, nutrition, or a condition patients commonly encounter. Across the collection, the standard is the same: evidence first, appropriate uncertainty, and enough clinical context to separate useful medicine from wellness marketing.

Start with the HormoneSynergy® Longevity Medicine Framework

New & recently updated:

Metabolic Health & Insulin Resistance

Clinical resources on insulin resistance, glucose regulation, metabolic syndrome, visceral fat, prediabetes, obesity and GLP-1-based care within a broader longevity medicine plan.

Kidney Health & Cardiovascular-Kidney-Metabolic Health

Kidney health belongs in the same clinical conversation as blood pressure, diabetes, insulin resistance, obesity and cardiovascular risk. These resources cover early detection, CKD, albuminuria, nutrition and CKM health.

Gut Health, Microbiome & Immune Signaling

Clinical education on the microbiome, intestinal barrier, fiber, inflammation, gut-brain signaling, immune biology and the growing connections between gut, metabolic and kidney health.

Food Quality, Vitamins, Supplements & Wellness Claims

Evidence-based guidance on nutrient gaps, supplement quality, interactions, food claims and longevity products, with an emphasis on where supplementation helps and where marketing outruns the evidence.

  • Phthalates and Hormone Disruption

    phthalates and hormone disruption showing a calm personal care product scene with subtle endocrine health imagery in HormoneSynergy®

    Phthalates are common chemicals used in plastics and personal care products, and they remain one of the most important endocrine disruptor topics in modern health. This guide explains what phthalates are, where exposure commonly happens, and why a practical longevity medicine approach focuses on reducing repeated unnecessary exposure.

  • BPA and Hormone Disruption: What It Means for Metabolism, Fertility, and Longevity

    Clinical editorial banner for BPA and hormone disruption showing a calm home food-storage scene with glass containers and subtle endocrine health imagery in HormoneSynergy®

    Bisphenol A (BPA) is one of the most widely studied endocrine disruptors. This guide explains how BPA affects hormone signaling, metabolism, fertility, and long-term health—and how a practical longevity medicine approach addresses exposure and resilience.

  • The Longevity Medicine Decision Framework: What Actually Matters vs What’s Noise

    Longevity medicine decision framework pyramid showing foundational health priorities like nutrition, strength training, aerobic fitness, sleep, and metabolic health compared to wellness tools in a clinical setting

    Confused by wellness trends, biohacking, and recovery tools? This guide shows what actually matters for longevity, what to prioritize, and how to evaluate health decisions without falling for hype.

  • Lifestyle Medicine vs Wellness Marketing: Research, Hype, Biohackers, and the Search for a Shortcut

    Editorial image contrasting foundational lifestyle medicine with wellness marketing tools in a clean clinical setting

    Modern wellness culture is full of bold claims, polished influencers, and expensive tools promising better energy, faster recovery, and longer life. This article explains the difference between real lifestyle medicine and predatory wellness marketing through the lens of HBOT, cold plunges, infrared sauna, and red light therapy.

  • Hyperbaric Oxygen Therapy (HBOT) in Longevity Medicine: Medical Uses vs Wellness Marketing

    Hospital-grade hyperbaric oxygen chamber in a clean clinical setting representing HBOT and longevity medicine

    Hyperbaric oxygen therapy is a legitimate medical treatment for specific conditions, but it is also one of the most overextended tools in wellness marketing. This guide explains the difference between true medical HBOT and mild hyperbaric chambers, what the evidence actually supports, and where the claims go too far.

  • Red Light Therapy in Longevity Medicine: Clinical Uses vs Marketing Claims

    Red light therapy panel in a clean clinical setting representing photobiomodulation and longevity medicine

    Red light therapy is widely promoted for skin, hair, recovery, inflammation, hormones, mitochondria, and anti-aging. This guide breaks down where photobiomodulation is legitimate, where the evidence is strongest, and where the claims move past the research.

  • Cold Plunges and Longevity: What the Research Actually Shows

    Cold plunge tub in a clean clinical wellness setting representing cold exposure research and longevity medicine

    Cold plunges are widely promoted for resilience, metabolism, recovery, and longevity, but many of the claims move ahead of the evidence. This guide breaks down what cold exposure may help, where the research is limited, and how it fits into real longevity medicine.

  • Infrared Sauna and Heat Therapy in Longevity Medicine: What the Research Actually Shows

    infrared sauna heat therapy in a clean clinical setting representing cardiovascular and longevity benefits

    Infrared sauna is often promoted for detox, fat loss, and longevity—but what does the evidence actually support? This guide breaks down heat therapy, cardiovascular health, and where claims go too far.

  • Libido and Hormone Transitions: Why Desire Changes Over Time

    Libido and hormone transitions illustration showing changes in desire related to hormones, stress, and physiology in longevity medicine

    Libido is influenced by hormones, brain function, stress, and metabolic health. During hormone transitions, changes in desire are common and often reflect broader physiologic shifts rather than a single issue.

  • Female Sexual Health and Hormones: Understanding Desire, Physiology, and Change

    Female sexual health and hormones illustration showing hormonal balance, vascular function, and brain signaling in longevity medicine

    Female sexual health is shaped by hormones, brain function, vascular health, and nervous system balance. In longevity medicine, changes in libido and function are often early indicators of broader physiologic shifts rather than isolated issues.

  • Erectile Dysfunction and Cardiovascular Risk: Why Blood Flow Matters More Than You Think

    Erectile dysfunction and cardiovascular risk illustration showing arterial blood flow and vascular health in longevity medicine

    Erectile dysfunction is often treated as a performance issue, but in many cases it is an early warning sign of cardiovascular disease. In longevity medicine, ED reflects vascular health, endothelial function, and systemic risk.

  • Healthy Bones and Muscles: A Longevity Medicine Approach to Strength, Density, and Aging Prevention

    Healthy Bones and Muscles: A Longevity Medicine Approach to Strength, Density, and Aging Prevention

    Bone loss and muscle decline are not inevitable. This guide explains how to preserve strength, prevent fractures, and build long-term resilience through nutrition, exercise, hormones, and longevity medicine strategies.