The Hormones Dr. Bruice Tests and Treats: An Overview of Your Hormonal System
The endocrine system is one of the most intricate communication networks in the human body—a web of chemical signals produced by multiple glands that regulate virtually every physiological process. When patients seek hormone optimization care, they are often surprised by the breadth of the hormonal evaluation that a comprehensive approach entails. Understanding which hormones matter, what each does, and how they interact with each other provides the foundation for understanding why individualized, whole-system hormonal care produces results that piecemeal approaches cannot.
Sex Hormones: Estrogen, Progesterone, and Testosterone
The sex steroids—estradiol, progesterone, and testosterone—are the most commonly addressed hormones in BHRT. They are produced primarily by the gonads (ovaries in women, testes in men) under the regulatory control of the hypothalamic-pituitary axis, with additional contributions from the adrenal glands.
Estradiol, the primary estrogen in premenopausal women, regulates reproductive function but also profoundly affects the brain, cardiovascular system, bones, skin, and metabolism. Progesterone, produced after ovulation, supports uterine health, sleep, mood, and neuroprotection—and provides the essential counterbalance to estrogen's proliferative effects. Testosterone, present in both sexes at different concentrations, drives energy, libido, muscle maintenance, insulin sensitivity, bone density, and mood.
These three hormones interact continuously: estrogen increases SHBG, which binds testosterone and reduces its free fraction; testosterone can aromatize to estradiol; progesterone competes with cortisol at receptor level. Understanding these interactions—not just measuring each hormone in isolation—is what distinguishes comprehensive hormone care from standard laboratory review.
SHBG: Sex Hormone Binding Globulin
SHBG is a carrier protein produced by the liver that binds sex hormones—particularly testosterone and estradiol—in the bloodstream, rendering them biologically inactive. Only "free" (unbound) hormone can enter cells and exert biological effects. SHBG levels are influenced by estrogen (which raises SHBG), insulin (which lowers it), thyroid status, and body composition. High SHBG effectively reduces free testosterone and free estradiol even when total levels appear normal—a common reason why patients have symptoms of hormone deficiency despite normal-looking total hormone values.
Adrenal Hormones: DHEA and Cortisol
The adrenal glands produce three categories of hormones: mineralocorticoids (aldosterone), glucocorticoids (cortisol), and adrenal androgens (primarily DHEA-S and androstenedione).
DHEA and DHEA-S serve as precursors for sex hormone production and have independent immunomodulatory, metabolic, and neurological effects. DHEA declines dramatically with age—losing 80–90% of peak levels by the 70s—contributing to declines in energy, immune competence, and sex hormone availability.
Cortisol, produced in response to stress and following circadian rhythms, is the body's primary stress hormone. Chronically elevated cortisol—from psychological stress, poor sleep, inflammation, or adrenal dysregulation—suppresses immune function, promotes visceral fat accumulation, suppresses sex hormone production, impairs thyroid conversion, and disrupts sleep. Chronically low cortisol (adrenal fatigue) produces profound fatigue, poor stress resilience, and hypoglycemia. Both patterns are clinically important and often missed without appropriate testing.
Pregnenolone: The Mother Hormone
Pregnenolone is the first product of cholesterol conversion in the steroidogenic cascade—the common precursor from which all steroid hormones are ultimately derived. It also functions as a neurosteroid, modulating memory, mood, and neuroprotection. Like DHEA, pregnenolone declines significantly with age, and deficiency affects the entire downstream hormonal architecture.
Thyroid Hormones: T3, T4, and TSH
The thyroid gland produces thyroxine (T4) and triiodothyronine (T3), which regulate the metabolic rate of every cell in the body. T4 is largely a prohormone that must be converted to active T3 in peripheral tissues (particularly the liver and kidneys). This conversion can be impaired by nutritional deficiencies (selenium, zinc, iodine), inflammation, stress, and certain medications—producing functional hypothyroidism even when TSH and T4 appear normal.
Reverse T3 (rT3) is an inactive form of T3 produced when the body is under stress—it competes with active T3 at thyroid receptors, effectively blocking thyroid activity. An elevated rT3:freeT3 ratio is a significant marker of functional hypothyroidism that standard TSH testing completely misses. Thyroid antibodies (anti-TPO and anti-thyroglobulin) identify autoimmune thyroid disease (Hashimoto's thyroiditis), which is the most common cause of hypothyroidism and requires specific monitoring and, in some patients, treatment modification.
Insulin and Metabolic Hormones
Insulin is a hormone produced by the pancreatic beta cells in response to glucose ingestion. Its primary function is to facilitate glucose uptake into cells—but chronically elevated insulin (from insulin resistance) has profoundly adverse hormonal effects: it suppresses SHBG, stimulates ovarian androgen production (a central driver of PCOS), promotes visceral fat accumulation, and interferes with thyroid hormone conversion. Fasting insulin and HOMA-IR (insulin resistance calculation) provide far more clinical information than fasting glucose or HbA1c alone, and they are included in Dr. Bruice's comprehensive metabolic panel.
IGF-1: Growth Hormone Proxy
Growth hormone (GH), secreted by the pituitary gland, declines progressively with age—losing approximately 14% of secretory capacity per decade. IGF-1 (insulin-like growth factor 1), produced in the liver in response to GH stimulation, is the standard clinical marker of GH status. Growth hormone deficiency contributes to reduced lean mass, increased visceral fat, impaired tissue repair, sleep disruption, and reduced quality of life. IGF-1 is measured as part of the comprehensive metabolic assessment to identify patients who may benefit from growth hormone secretagogue peptide therapy.
How These Hormones Interact
These hormones do not operate in isolated silos—they are deeply interconnected. Cortisol suppresses testosterone production. Insulin suppresses SHBG and stimulates androgen production. Thyroid hormones regulate the speed of all metabolic processes, including hormone production and clearance. Estrogen raises SHBG, affecting free testosterone. Progesterone modulates cortisol receptor sensitivity. Growth hormone supports IGF-1, which supports muscle and bone response to sex hormones.
This interconnectedness is why comprehensive testing—not just a few isolated markers—is essential. And it is why a provider who understands the whole hormonal system produces better clinical outcomes than one focused on any single hormone.
Comprehensive Hormonal Care with Dr. Bruice
Kenton Bruice, M.D., evaluates and treats the full spectrum of hormonal health at his clinics in Denver, Aspen, and St. Louis. His comprehensive testing approach, whole-system clinical perspective, and individualized treatment protocols deliver outcomes that reflect the full complexity of the human hormonal system. Contact Dr. Bruice's office to schedule your comprehensive hormonal evaluation today.