10/07/2025
🔬 Deep Dive: SHBG — The Unsung Regulator of Your Hormones
Most people check their testosterone or estrogen levels…
but few realize that SHBG (S*x Hormone–Binding Globulin) determines how much of those hormones are actually usable by the body.
⚙️ What SHBG Does
SHBG is a protein produced by your liver that binds tightly to s*x hormones — especially testosterone, dihydrotestosterone (DHT), and estradiol.
When bound, these hormones are inactive. Only the unbound or “free” fraction exerts biological effects.
Think of SHBG as your hormone traffic controller — it decides how much hormone is “free to act” versus “stored for later.”
📉 Low SHBG — What It Can Mean
Low SHBG can make hormones appear high on lab tests but still leave you symptomatic.
Common functional causes include:
• Insulin resistance or high insulin levels (often seen with metabolic dysfunction or PCOS)
• Obesity
• Hypothyroidism
• Androgen excess
• High growth hormone or cortisol levels
• Inflammation or liver dysfunction
💬 Low SHBG often signals metabolic or inflammatory stress rather than a primary hormone problem.
📈 High SHBG — What It Can Mean
When SHBG is elevated, most of your testosterone or estrogen becomes bound and inactive.
This can cause fatigue, low libido, poor recovery, or menstrual irregularities even if your total hormone levels look fine.
Common functional drivers include:
• Estrogen dominance
• Liver stress or overactivation (especially with excess estrogen metabolism)
• Thyroid hyperactivity or excess thyroid hormone
• Nutrient deficiencies (especially protein or zinc)
• Certain medications (oral contraceptives, anticonvulsants, etc.)
⚖️ Finding the Balance
In functional medicine, we don’t just look at “normal” lab ranges — we aim for optimal:
• Men: typically 20–60 nmol/L
• Women: typically 30–120 nmol/L (varies by age and hormonal status)
But these numbers mean little without context. The key is to interpret SHBG alongside:
• Total & Free Testosterone
• Estradiol
• Albumin
• Insulin or fasting glucose
• Thyroid panel
• Liver function tests
🧠 Bottom Line
SHBG is more than a lab value — it’s a metabolic and hormonal marker that connects your liver, thyroid, insulin balance, and s*x hormones.
When SHBG is off, it’s often a clue that your body’s regulatory systems are out of sync.
Functional tip: balancing insulin, supporting liver health, optimizing thyroid function, and ensuring nutrient sufficiency are key steps to bringing SHBG — and your hormones — back into harmony.