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

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.

Body Composition, Bone & Muscle Longevity

Resources on DEXA, SECA, visceral fat, lean mass, sarcopenia, bone density, exercise and preservation of physical reserve with age.

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.

  • Collagen Peptides for Longevity: Skin, Joints, Bone, and Structural Health

    by Daniel Soule
    Collagen peptides for skin elasticity joint health bone density and connective tissue longevity medicine HormoneSynergy Portland Oregon

    Collagen peptides may support skin elasticity, joint comfort, bone matrix, and connective tissue resilience. Here’s how they fit into a longevity medicine framework.

  • Inflammation and Immune Signaling: Why Regulation Matters More Than “Boosting”

    by Daniel Soule
    Sleep and immune resilience clinical concept HormoneSynergy Longevity Medicine Portland Oregon

    Inflammation is part of normal immune signaling, but chronic low-grade inflammation can alter how the immune system responds over time. A longevity medicine perspective on inflammation, immune regulation, and resilience.

  • Sleep and Immune Resilience: Why Recovery Shapes Immune Function

    by Daniel Soule
    Sleep and immune resilience clinical concept HormoneSynergy Longevity Medicine Portland Oregon

    Sleep plays a central role in immune regulation, inflammation, and recovery. Poor sleep alters immune signaling and reduces resilience over time.

  • Zinc and Viral Illness Duration: What the Evidence Actually Suggests

    by Daniel Soule
    Zinc immune function viral illness duration clinical concept HormoneSynergy Longevity Medicine Portland Oregon

    Zinc plays a role in immune cell function and may influence the duration of certain viral illnesses when used early. Its effects are context-dependent and not universal.

  • Vitamin D and Immune Function: Why Levels Matter for Immune Regulation

    by Daniel Soule
    Vitamin D immune function clinical concept HormoneSynergy Longevity Medicine Portland Oregon

    Vitamin D plays a central role in immune regulation and inflammatory balance. Suboptimal levels are common and can influence how the body responds to illness and stress.

  • Gut Microbiome and Immune Regulation: Why Gut Health Matters for Immune Resilience

    by Daniel Soule
    Gut microbiome and immune regulation clinical illustration for HormoneSynergy® Longevity Medicine Portland Lake Oswego USA

    The gut microbiome plays a central role in immune regulation, inflammation, and barrier function. Learn how gut health shapes immune resilience over time from a longevity medicine perspective.

  • Immune “Boosting” vs Immune Support: What Actually Matters

    by Daniel Soule
    Immune system support vs immune boosting concept in clinical setting HormoneSynergy Portland Oregon longevity medicine

    The idea of “boosting” your immune system is everywhere. The reality is more nuanced—and more grounded in physiology than marketing.

  • Creatine and Metabolic Health: Muscle, Glucose, and Insulin Sensitivity

    by Daniel Soule
    Creatine and metabolic health insulin glucose longevity medicine image HormoneSynergy Portland Oregon

    Creatine is often discussed for muscle, but its role in metabolism is just as important. It may help support glucose handling and insulin sensitivity through its effects on muscle and energy systems.

  • Creatine and Brain Health: Energy, Cognition, and Healthy Aging

    by Daniel Soule
    Creatine and brain health longevity medicine image focused on cognition energy and healthy aging HormoneSynergy Portland Oregon

    Creatine is usually discussed in relation to muscle, but it also plays a role in brain energy metabolism. In longevity medicine, that makes it clinically relevant beyond the gym.

  • Creatine for Women in Longevity Medicine: Strength, Energy, and Aging

    by Daniel Soule
    Creatine for women longevity medicine image focused on strength recovery and healthy aging HormoneSynergy Portland Oregon

    Creatine is not just for men or athletes. It may support muscle, recovery, brain energy, and healthy aging in women across the lifespan.

  • Creatine and Muscle Loss With Aging: Why It Matters Beyond the Gym

    by Daniel Soule
    Creatine and muscle loss with aging image focused on strength muscle preservation and healthy longevity medicine

    Creatine is not just for athletes. In longevity medicine, it may help support muscle, strength, recovery, and functional aging, especially when paired with resistance training.

  • Creatine and Kidney Function: What the Evidence Actually Shows

    by Daniel Soule
    Creatine kidney function and creatinine levels explained in longevity medicine HormoneSynergy Portland Oregon

    Creatine may raise serum creatinine, but evidence shows it does not impair kidney function. Understanding the difference matters.