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Sex Hormone-Binding Globulin (SHBG) Blood Test: A Key Marker of Men’s Hormonal Balance

The Sex Hormone-Binding Globulin (SHBG) Blood Test, part of the PlexusDx Men’s Hormone Blood Test, provides critical insight into hormone regulation and availability in the body. SHBG is a protein made by the liver that binds tightly to sex hormones, including testosterone and estrogen, transporting them through the bloodstream. While this process is essential, it also determines how much of these hormones are biologically active and available for use by the body.

Because SHBG directly influences hormone activity, its measurement offers deeper understanding when evaluating men’s health, particularly in situations where total testosterone levels don’t match symptoms like low libido, erectile dysfunction, infertility, mood changes, or loss of muscle mass.

Why SHBG Matters in Men’s Health

Testosterone testing is common in men’s health evaluations, but total testosterone alone can be misleading. This is because much of testosterone is bound to proteins like SHBG or albumin. Only a small percentage, known as free testosterone, is biologically active and able to exert its effects in tissues. SHBG plays a major role in controlling that balance.

  • High SHBG: Too much SHBG binds excess testosterone, leaving less available as free testosterone. This can cause symptoms of low testosterone even if total levels appear normal.
  • Low SHBG: Insufficient SHBG may increase free testosterone levels, sometimes contributing to acne, excess hair growth, or hormonal imbalances. In men, low SHBG is also linked to insulin resistance, metabolic syndrome, and obesity.

By measuring SHBG alongside total and free testosterone, doctors and patients gain a more accurate picture of true hormonal balance and function.

Common Reasons to Check SHBG Levels

The SHBG blood test is often ordered when symptoms suggest hormonal imbalance but total testosterone results don’t provide clear answers. Reasons include:

  • Unexplained low libido or erectile dysfunction despite normal testosterone levels.
  • Infertility evaluations, since SHBG can affect sperm production through testosterone availability.
  • Monitoring metabolic conditions such as obesity, type 2 diabetes, or insulin resistance, which are linked to low SHBG.
  • Thyroid disorders, as both hypothyroidism and hyperthyroidism can influence SHBG production.
  • Assessing hormone replacement therapy outcomes in men undergoing testosterone treatment.

Factors That Influence SHBG Levels

SHBG is not static and can be affected by several internal and external factors, including:

  • Sex hormones: Higher estrogen increases SHBG, while higher testosterone tends to lower it.
  • Thyroid function: Hyperthyroidism raises SHBG; hypothyroidism lowers it.
  • Insulin and diet: High insulin and poor metabolic health reduce SHBG levels.
  • Liver health: Since SHBG is made in the liver, conditions like fatty liver disease or liver dysfunction affect its production.
  • Age: SHBG tends to increase with age, altering the balance between total and free testosterone.

Reference Ranges for SHBG

Reference ranges for SHBG can vary by laboratory, but typical ranges for adult men are:

  • Standard reference range: 10 – 57 nmol/L
  • Functional/optimal range (men): 20 – 40 nmol/L

Values outside of these ranges may indicate underlying hormonal, thyroid, or metabolic conditions and should be interpreted alongside other hormone tests such as total testosterone, free testosterone, and albumin.

Symptoms of Imbalanced SHBG Levels

Because SHBG alters hormone availability, imbalances can mimic low or high testosterone symptoms:

  • High SHBG (low free testosterone): Fatigue, decreased sex drive, erectile dysfunction, muscle weakness, infertility, mood changes.
  • Low SHBG (high free testosterone): Acne, excessive body hair, possible links to metabolic syndrome, insulin resistance, obesity, fatty liver disease.

How the SHBG Test Works

The PlexusDx SHBG test is performed using a simple at-home dried blood spot collection on an ADX card. This convenient method eliminates the need for a traditional blood draw, while still providing laboratory-quality results. After collection, the sample is mailed to the lab for analysis, with results delivered securely online.

This process is fast, accurate, and minimally invasive, making it easy to check SHBG and other hormones from the comfort of home.

How SHBG Testing Fits Into a Men’s Hormone Panel

The PlexusDx Men’s Hormone Blood Test doesn’t just measure SHBG—it evaluates multiple biomarkers that together give a complete picture of male hormone health. By combining SHBG with total testosterone, free testosterone, estradiol, and other key markers, the panel helps identify whether symptoms are due to hormone deficiency, binding imbalances, or other related health issues.

Improving SHBG Balance Naturally

If SHBG results are abnormal, several lifestyle and medical approaches may help:

  • Weight management: Reducing excess body fat improves insulin sensitivity, which can normalize SHBG.
  • Balanced nutrition: Diets rich in whole foods, adequate protein, and micronutrients support liver and hormone health.
  • Exercise: Both resistance training and aerobic exercise can help regulate hormone levels.
  • Addressing thyroid or liver conditions: Proper management of these conditions is essential for SHBG regulation.
  • Medical treatment: In some cases, doctors may adjust or prescribe hormone therapies based on SHBG and testosterone levels.

Key Takeaways

  • The SHBG Blood Test measures the protein that regulates how much testosterone and estrogen are active in the body.
  • High SHBG can lower free testosterone, causing symptoms of low testosterone even when total levels are normal.
  • Low SHBG is linked to metabolic health issues like insulin resistance and obesity.
  • Testing SHBG provides clarity when symptoms and testosterone results don’t align.
  • The PlexusDx Men’s Hormone Blood Test uses at-home dried blood spot collection for convenient, accurate hormone testing.

Final Thoughts

The Sex Hormone-Binding Globulin (SHBG) Blood Test is an essential tool for understanding men’s hormone health. By going beyond total testosterone and evaluating hormone availability, it helps uncover hidden imbalances that affect energy, fertility, mood, and sexual health. With the convenience of at-home dried blood spot collection, PlexusDx makes it easier than ever to gain actionable insights into your hormone balance and overall well-being.