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.

  • Triglyceride-to-HDL Ratio: What It Can Tell You About Metabolic Health

    Triglyceride-to-HDL ratio illustrated with fasting insulin, ApoB, remnant particles, and metabolic health markers.

    The triglyceride-to-HDL ratio is a useful clue to insulin resistance and triglyceride-rich lipoprotein metabolism, but it is not a stand-alone cardiovascular risk test. Its greatest value comes from interpreting it alongside fasting insulin, ApoB, remnant cholesterol, body composition, and the rest of the metabolic picture.

  • Why Normal Cholesterol Labs Can Miss Cardiovascular Risk

    Why normal cholesterol labs can miss cardiovascular risk visualization for HormoneSynergy longevity medicine

    A standard lipid panel remains useful, but LDL-C alone can underestimate atherogenic particle burden. ApoB, non-HDL-C, Lp(a), metabolic markers, calculated risk, and selective plaque imaging can reveal what “normal cholesterol” misses.

  • ApoB vs LDL-C: What Actually Matters for Cardiovascular Risk?

    Conceptual preventive cardiology image showing LDL-C and ApoB lab vials with different particle patterns, representing cholesterol content versus atherogenic particle number.

    LDL-C measures how much cholesterol is being carried inside LDL particles. ApoB provides an estimate of how many atherogenic particles are circulating. Most of the time the two move together, but when they do not, ApoB can reveal cardiovascular risk that a standard cholesterol panel may underestimate. Metabolic health, triglycerides, Lp(a), family history and imaging add important context without making atherogenic particle exposure irrelevant.

  • Omega-3 and Triglycerides: What the Evidence Shows

    Physician reviewing a lipid panel with a patient beside salmon, olive oil, walnuts, greens, and RetzlerRx® Pure Omega supplements.

    EPA and DHA can lower triglycerides, but formulation quality, concentration, dose and the person’s broader metabolic health all influence how omega-3 support should be used.

  • Type Five and Longevity: From Knowing to Embodying

    Enneagram Type Five longevity image showing knowledge becoming embodied health practice, movement, prevention, and sustainable care in the HormoneSynergy approach.

    Type Fives often bring curiosity, independence, analysis, and a deep desire to understand complex systems. In health, that can be a real strength. But when knowledge stays in the mind and never becomes lived practice, the body may remain under-cared for. In longevity work, the growth path for Type Five is learning to translate insight into embodied action.

  • Magnesium for Metabolic Health and Sleep: A Longevity Medicine Perspective

    Magnesium and metabolic health with sleep and nervous system regulation shown in a clean clinical dashboard for longevity medicine

    Magnesium plays an important role in insulin sensitivity, energy production, nervous system regulation, and sleep quality. This guide explains how magnesium fits into a physician-led longevity medicine approach to metabolic health, recovery, and healthy aging.

  • The Story Keeping You Stuck

    The Story Keeping You Stuck hero image for HormoneSynergy® Longevity Medicine showing a narrow industrial corridor with distant light representing old patterns, internal pressure, and the possibility of change

    Many people don’t stay stuck because they don’t know what to do—they stay stuck because they keep repeating the same story about themselves. This article explores how identity, past experiences, and internal narratives shape behavior—and how awareness can begin to change it.

  • Muscle Mass, Glucose Control, and Longevity

    Muscle mass, glucose control, and metabolic health visualization in a clinical longevity medicine setting

    Muscle mass plays a major role in glucose disposal, insulin sensitivity, metabolic resilience, and healthy aging. In longevity medicine, preserving muscle is not just about strength or appearance. It is a core part of metabolic health.

  • Mitochondrial Function and Energy Production in Longevity Medicine

    Mitochondrial function and cellular energy production visualization in a clinical longevity medicine setting

    Mitochondria drive energy production at the cellular level. When function declines, it may affect metabolism, recovery, and long-term resilience.

  • MASLD (Formerly NAFLD): What Fatty Liver Tells Us About Metabolic Health

    MASLD formerly NAFLD fatty liver, visceral fat and metabolic health illustration for HormoneSynergy longevity medicine

    Fatty liver is often discovered by accident, sometimes with completely normal liver enzymes. Now called metabolic dysfunction-associated steatotic liver disease, or MASLD, it can offer an early look at insulin resistance, visceral fat, cardiovascular risk, and the metabolic changes occurring well before more obvious disease appears.

  • ALT and AST and Liver Health in Longevity Medicine

    ALT and AST liver enzyme visualization in a clinical longevity medicine setting

    ALT and AST are commonly used liver enzymes, but even mild elevations may reflect deeper metabolic stress. In longevity medicine, they help provide early insight into liver and cardiometabolic health.

  • ApoA1 and HDL Function in Longevity Medicine

    ApoA1 and HDL function visualization in a clinical longevity medicine setting

    ApoA1 is the main protein component of HDL and helps reflect HDL function, cholesterol transport, and vascular resilience. It offers a more useful view of protective lipid physiology than HDL cholesterol alone