How to normalize Sex Hormone-Binding Globulin (SHBG) and increase free testosterone levels?

Normalizing SHBG and Increasing Free Testosterone

To normalize Sex Hormone-Binding Globulin (SHBG) and increase free testosterone levels, focus on weight management through regular physical activity and dietary modifications, as these are the most effective non-pharmacological interventions. High SHBG levels bind testosterone, reducing its bioavailability and potentially causing symptoms of low testosterone despite normal total testosterone levels.

Understanding SHBG and Free Testosterone

SHBG is a protein that binds to sex hormones, particularly testosterone, reducing the amount of free (bioavailable) testosterone in circulation. When SHBG is elevated:

• Only about 2% of total testosterone circulates as free testosterone 1
• Normal total testosterone levels may coexist with low free testosterone (occurs in 17.2% of men with erectile dysfunction) 2
• This condition becomes more common with age (26.3% in men over 60) 2

Factors That Affect SHBG Levels

Factors that increase SHBG:

• Advanced age 2
• Oral estrogens and contraceptives 3
• Hyperthyroidism 3
• Liver disease/cirrhosis 2
• HIV infection 2
• Malnutrition/low BMI 3

Factors that decrease SHBG:

• Obesity/higher BMI 4
• Insulin resistance 4
• Regular physical activity 3
• Certain androgens 5

Strategies to Normalize SHBG and Increase Free Testosterone

1. Weight Management

• Weight reduction for overweight or obese individuals is the most effective strategy to lower SHBG 3, 4
• Calorie restriction has been shown to reduce insulin levels, which subsequently increases SHBG 4
• Note that very low BMI can also increase SHBG, so aim for a healthy weight range

2. Physical Activity

• Regular exercise improves metabolic health and can help normalize SHBG levels 3
• Resistance training is particularly effective for increasing testosterone production

3. Dietary Modifications

• Focus on balanced nutrition with adequate protein intake
• Avoid excessive alcohol consumption
• Ensure sufficient zinc and vitamin D intake, which support testosterone production
• Avoid liquorice and grapefruit juice, which can affect hormone metabolism 6

4. Medication Review

• If on oral contraceptives or hormone replacement therapy, consider:
  • Discontinuing or switching to non-hormonal options 3
  • Changing from oral to transdermal administration routes (which have less impact on SHBG) 3

5. Medical Evaluation

For persistent issues, medical evaluation should include:

• Comprehensive hormone panel: total and free testosterone, SHBG, estradiol, FSH, LH 3
• Thyroid function tests: TSH, free T4 3
• Liver function tests 3
• Morning cortisol and ACTH to evaluate adrenal function 3

Monitoring Progress

• Measure SHBG and free testosterone levels every 3-6 months 3
• Use calculated free testosterone (cFT) rather than free androgen index (FAI), as FAI correlates poorly with actual free testosterone levels 7, 1
• Monitor for improvement in symptoms (energy levels, libido, erectile function)

Important Considerations

• Age significantly affects SHBG levels, with older men (>60 years) having higher SHBG and lower free testosterone despite normal total testosterone 2
• Total testosterone alone is insufficient to exclude hypogonadism, particularly in older men 2
• If considering testosterone replacement therapy, this should only be done under medical supervision and after confirming hypogonadism 6

By focusing on these strategies, particularly weight management and regular physical activity, most individuals can effectively normalize SHBG levels and improve free testosterone availability.