SHBG (Sex Hormone Binding Globulin): What You Need to Know

Understanding your hormone levels goes beyond just measuring testosterone or estrogen. SHBG (sex hormone binding globulin) plays a critical role in determining how much of your sex hormones are actually available for your body to use.

What Is SHBG?

SHBG is a protein made by your liver. It binds tightly to three sex hormones found in both men and women: estrogen, dihydrotestosterone (DHT), and testosterone. SHBG acts as a transport protein, carrying these hormones throughout the bloodstream to the tissues that need them.

Why SHBG Matters for Testosterone

While SHBG binds to multiple hormones, testosterone is the critical hormone when it comes to testing and clinical significance. SHBG controls the amount of testosterone that your body tissues can use. When testosterone is bound to SHBG, it is not available for your cells — only free and loosely bound testosterone (bioavailable testosterone) can be utilized.

This is why two people with the same total testosterone level can feel very different. The person with lower SHBG has more free testosterone available for their body to use.

What Affects SHBG Levels?

SHBG concentrations fluctuate based on several factors including sex, age, body weight, liver health, and thyroid function. A decrease in SHBG results in higher free testosterone and bioavailable testosterone, while an increase reduces the amount of usable hormone.

Conditions Associated with Low SHBG

Reduced SHBG levels may correlate with:

• Obesity
• Type 2 diabetes
• Hypothyroidism
• Acromegaly (excessive growth hormone production)

Conditions Associated with High SHBG

Elevated SHBG levels may relate to:

• Hepatitis
• Hyperthyroidism
• HIV

Why SHBG Testing Matters

If you are experiencing symptoms of low testosterone — fatigue, reduced libido, difficulty building muscle, or mood changes — but your total testosterone appears normal, SHBG testing may reveal the missing piece. High SHBG can effectively reduce your usable testosterone even when total levels look adequate on paper.

At Rewind Anti-Aging, we include SHBG in our comprehensive hormone panels to get the full picture of your hormonal health and develop targeted treatment plans that address the root cause of your symptoms.