The HealifyMD glossary

How to use this glossary

Health care has its own vocabulary, and much of it shows up exactly when you're trying to make a decision: on a lab report, in a treatment description, or in a conversation about whether a medicine is FDA-approved. Each entry here explains one term in everyday language, says why it matters in your 40s, 50s and beyond, and points to related terms and pages.

Every definition is written for education, not diagnosis. Reference ranges differ between labs, and a number only means something alongside your symptoms, history and other results. If a term raises a question about your own care, bring it to your clinician.

Lab markers

These are the blood tests most often ordered in hormone, metabolic and longevity care. Each entry covers what the test measures, when it's useful, what can skew it and how it's usually interpreted. A few that come up most often:

• ApoB and lipoprotein(a): measures of the particles that drive plaque in arteries, beyond a standard cholesterol panel.
• HbA1c, fasting insulin and HOMA-IR: ways of looking at blood sugar control and insulin resistance.
• Total testosterone, free testosterone and SHBG: the trio used to judge whether testosterone is truly low.
• Estradiol, FSH and LH: hormones that shift through perimenopause and help explain changes in the ovaries or testes.
• TSH, free T4 and free T3: the thyroid tests, and why the order you check them in matters.
• Ferritin, vitamin D, hematocrit and PSA: markers that matter for energy, bones and safe hormone therapy.

Hormones and the body

These entries explain the hormones themselves and the conditions linked to them. They're useful background when you're reading about menopause, low testosterone, weight change or sleep. Examples include estrogen, progesterone, testosterone, andropause, hypogonadism, vasomotor symptoms such as hot flashes, genitourinary syndrome of menopause, insulin resistance, sarcopenia and aromatization, the process that turns testosterone into estrogen.

Treatments and drug classes

Medicines are easier to understand by class than by brand name. These entries describe how each group of drugs works, what it's approved for, the main side effects and the warnings to know. They include GLP-1 receptor agonists and GIP/GLP-1 dual agonists for weight and blood sugar, PDE5 inhibitors for erectile dysfunction, 5-alpha-reductase inhibitors for hair loss and prostate enlargement, aromatase inhibitors and SERMs that change estrogen activity, GHRH analogs such as sermorelin, and bioidentical hormones.

Where a medicine at HealifyMD is compounded, the entry says so plainly. Compounded medications are not FDA-approved and are not the same as brand-name products.

Regulation and care

Some of the most important words in health care aren't medical at all. They describe how a product is regulated or how care gets paid for, and they can change how much confidence you should place in a claim. Key entries:

• FDA-approved and FDA-cleared: what each label means and which products earn it.
• Compounded medication, 503A pharmacy and 503B outsourcing facility: who makes compounded drugs and how they're overseen.
• Off-label use: prescribing an approved drug for a use not on its label.
• Lab-developed test and reference range: how lab results are produced and judged.
• Prior authorization and letter of medical necessity: the paperwork that often decides insurance coverage.

How these definitions are written

Entries draw on government and professional sources such as the FDA, MedlinePlus, the National Institutes of Health, the CDC and specialty societies, and each one lists its references. Content is reviewed under our editorial policy, with medical review by Dr. Vanessa Niles, R.N., M.D., F.A.C.O.G. We update entries when guidance or regulatory status changes, especially for fast-moving areas such as compounded peptides and weight-loss medicines.