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.

  • Triglycerides and Metabolic Health

    Triglycerides clinical illustration showing circulating blood lipids, fat storage, and metabolic health relationship

    Triglycerides are a type of fat found in the blood that reflect how the body stores and uses energy. Elevated levels are often associated with insulin resistance, visceral fat, and increased cardiometabolic risk.

  • Brain Fog, Cognitive Function, and Longevity

    Brain fog cognitive function concept showing contrast between mental fatigue and clarity in calm natural setting HormoneSynergy Portland Oregon USA

    Brain fog is often an early signal of metabolic, hormonal, or inflammatory imbalance. Learn what it means for long-term health.

  • Longevity Medicine: A Preventive Guide to Healthspan, Diagnostics, and Healthy Aging

    Longevity medicine hero image showing diagnostics metabolic health hormones preventive cardiology and healthy aging at HormoneSynergy

    Longevity medicine is a preventive medical approach focused on identifying disease risk before symptoms appear. Learn how advanced diagnostics, metabolic health evaluation, preventive cardiology, hormone assessment, and body composition testing support healthier aging and improved healthspan.

  • Hormones and Muscle Loss After 40: Why Strength Declines With Age

    hormones and muscle loss after 40

    Many adults begin losing muscle mass after age 40 due to hormonal shifts, reduced physical activity, metabolic changes, and lifestyle factors. Understanding how hormones influence muscle maintenance can help guide strategies for preserving strength, metabolic health, and long-term vitality.

  • Bioidentical Hormone Therapy vs Synthetic Hormones: What’s the Difference?

    Bioidentical vs synthetic hormone therapy

    Many patients researching hormone therapy encounter both bioidentical and synthetic hormones. Understanding the differences in structure, formulation, and clinical use can help individuals make informed decisions when discussing hormone therapy options with their physician.

  • Testosterone Therapy for Men Over 40: What to Know Before You Start

    Testosterone Therapy for Men Over 40: What to Know Before You Start

    Testosterone levels often change gradually with age, but symptoms such as fatigue, reduced strength, low libido, and loss of vitality can have many causes. Learn how testosterone therapy for men over 40 is evaluated and when a physician-guided assessment may help.

  • Signs of Hormone Imbalance After 40

    symptoms of hormone imbalance and menopause

    Hormone levels change with age, often affecting energy, sleep, mood, metabolism, and body composition. Learn the common signs of hormone imbalance after 40 and when a medical evaluation may help identify underlying causes and potential treatment options.

  • What Are Bioidentical Hormones? A Preventive Longevity Medicine Guide

    Bioidentical hormone therapy at HormoneSynergy®

    Bioidentical hormones are structurally identical to the hormones your body naturally makes. Learn how personalized BHRT may support energy, sleep, body composition, mood, sexual health, and healthy aging when guided by evidence-based medical evaluation.

  • Triglycerides and Metabolic Health: An Early Warning Sign

    Triglycerides metabolic health concept showing physician reviewing lipid panel and metabolic markers HormoneSynergy Portland Oregon USA

    Triglycerides are more than a cholesterol number. They can reflect insulin resistance and metabolic health early.

  • The 12 Most Important Medical Tests for Longevity, Disease Prevention, and Early Detection

    Medical tests for longevity including blood biomarkers, DEXA body composition scans, and cardiovascular imaging for early disease detection.

    Many serious diseases develop silently for years before symptoms appear. Preventive longevity medicine focuses on identifying health risks early using targeted testing. These twelve medical tests help detect cardiovascular disease, metabolic dysfunction, hormonal imbalance, and other hidden risks long before they become major health problems.

  • Lifestyle Medicine vs Longevity Medicine: Why Prevention Requires More Than Lifestyle Alone

    Lifestyle medicine vs longevity medicine comparison at HormoneSynergy® Longevity Medicine Clinic in Portland and Lake Oswego.

    Lifestyle habits play a powerful role in long-term health, but prevention is not simply about diet and exercise. Evidence-based preventive longevity medicine integrates lifestyle medicine with advanced diagnostics, metabolic evaluation, and targeted medical therapies when needed to detect disease earlier and improve long-term health outcomes.

  • The Three Levels of Preventive Longevity Evaluation

    Doctor discussing the three levels of preventive longevity evaluation with a patient including basic prevention, advanced metabolic testing, and precision longevity medicine assessment

    Preventive longevity medicine often uses a tiered evaluation model that ranges from basic metabolic screening to advanced cardiovascular imaging. Understanding these three levels can help individuals choose the depth of health evaluation that best matches their risk factors and long-term prevention goals.