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.

  • I Heard You Say I’m Adorable. Now Let’s Talk About Hearing Loss.

    Freshly groomed black Shepadoodle puppy Aria listening alertly beside her doghouse in a HormoneSynergy editorial image about age-related hearing loss, hearing aids, and brain health.

    Aria’s ears were the last of her senses to come online, but they now detect every compliment, treat bag, and suspicious sound in the house. Humans are not always so fortunate. Hearing often fades gradually with age, and the consequences reach well beyond turning up the television.

  • Red Meat, Pancreatic Cancer, and What the New Study Actually Found

    Red Meat, Pancreatic Cancer, and What the New Study Actually Found

    A new meta-analysis found a weak association between higher red-meat intake and pancreatic cancer—but no statistically significant association for processed meat. The practical advice remains sensible. The headline circulating online does not.

  • Does Hormone Therapy Cause Thyroid Cancer? Not So Fast.

    Midlife woman discussing menopausal hormone therapy and thyroid cancer research with a clinician in a preventive medicine consultation.

    A large observational study found a modest association between menopausal hormone therapy and thyroid cancer, particularly after five years of use. It did not prove that hormone therapy causes thyroid cancer—and it is not a reason to abruptly stop treatment.

  • Seed Oils Are Not Poison. The Fryer Is Not Innocent.

    Commercial deep fryer contrasted with olive oil and whole foods in a home kitchen, illustrating the difference between repeatedly heated fryer oil and thoughtful cooking for metabolic and cardiovascular health.

    Seed oils have become a convenient villain for nearly every modern metabolic problem. The evidence does not support calling them poison, but it does support asking harder questions about repeated frying, oxidized oils, ultra-processed food, excess calories, and the dietary pattern surrounding them.

  • I Can See Clearly Now. Humans, Apparently, Have More Complicated Problems.

    Aria, a freshly groomed black Shepadoodle puppy, looking through a glass door with her eyes clearly visible in a HormoneSynergy editorial image about aging eyesight and healthy vision.

    Aria’s first real grooming uncovered two very important things: her eyes and an even more adorable face. It also raised a serious question. Eyes change with age, but how much vision loss is actually inevitable—and how much can humans prevent?

  • Hormones, Weight Loss and Detoxification: Where Sulforaphane Fits

    Physician discussing hormone metabolism, weight loss and sulforaphane with a patient alongside cruciferous vegetables and liver metabolism imagery.

    Hormones are metabolized, some environmental pollutants are stored in body fat, and significant weight loss can change their circulation. Those facts are real. They do not mean everyone using hormone therapy or a GLP-1 medication needs a detox program. Here is a more practical look at liver function, the gut, estrogen metabolism, fat loss, glucoraphanin and sulforaphane.

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  • Apparently, I Need Friends: Dogs, Connection and Healthy Boundaries

    Aria, a black Shepherd-Doodle puppy, learning about friendship, social connection, training and healthy boundaries with other dogs.

    Aria has been thinking about friendship, dog parks, training, boundaries, and why Dr. Retzler and Daniel approach her social life so differently. One encourages connection; the other watches for risk, rough play, and damage to the new wood floors. Somewhere between freedom and protection, Aria is learning that healthy relationships—canine and human—depend on trust, movement, good judgment, and knowing when to stay, pause, or leave.

  • Postmenopausal Bleeding Is Never "Just Hormones"

    Postmenopausal bleeding and hormone therapy evaluation showing the uterus, transvaginal ultrasound, endometrial biopsy and progesterone protection from HormoneSynergy®.

    Bleeding after menopause is often caused by benign conditions or changes in hormone therapy, but it can also be the first sign of endometrial cancer. Updated 2026 ACOG guidance now recommends a more comprehensive initial evaluation for most patients. Here is what women using menopausal hormone therapy should know about ultrasound, biopsy, progesterone protection, endometrial thickness, and when bleeding needs investigation.

  • Every Time You Move, Your Muscles Send Signals Your Whole Body Can Hear

    An older woman and man performing resistance exercises as subtle anatomical pathways illustrate myokines carrying signals from contracting muscles to organs throughout the body.
    By Daniel Soule, Owner and Clinic Director, HormoneSynergy® Most of us were taught to think of muscle as the machinery that moves the body. It hel...
  • Your Gut Has a Clock. Stop Feeding It at Midnight.

    A quiet kitchen at night with a clock and closed refrigerator, representing late-night eating and gut circadian rhythm.

    Late-night eating is not just about calories or willpower. The gut has its own circadian timing system, and eating during the body’s biological night may interfere with digestion, motility, glucose handling, and sleep.

  • CoQ10 and Statins: Helpful Support, Not a Statin Replacement

    Middle-aged woman discussing CoQ10, statins, muscle symptoms, and heart health with a clinician in a longevity medicine consultation.

    Statins can lower CoQ10 levels, but that does not mean everyone on a statin needs a supplement. Here is where CoQ10 may help, where the evidence is mixed, and why it belongs in a bigger cardiovascular longevity conversation.