Normal SHBG Levels in Adults
Normal SHBG levels in adult men range from approximately 11-66 nmol/L, with women having higher levels averaging 58.9 nmol/L compared to men at 32.7 nmol/L. 1, 2, 3
Reference Ranges by Sex
Adult Men
- Mean SHBG: 29.4-32.7 nmol/L 2, 3, 4
- Reference interval: 11.5-66.3 nmol/L (2.5th to 97.5th percentile) 4
- Clinical population data shows range of 6-109 nmol/L, with mean 31.8 nmol/L 2
- Only 5.6% of men have SHBG >60 nmol/L 2
Adult Women
- Mean SHBG: 58.9 nmol/L 3
- Women consistently have significantly higher SHBG levels than men (p<0.001) 3
Age-Related Changes
SHBG increases significantly with age in men, requiring age-stratified interpretation: 2, 4
Younger Men (≤54 years)
Older Men (≥55 years)
- Mean SHBG: 36.6 nmol/L (range 11-109 nmol/L) 2
- 9% have SHBG >60 nmol/L 2
- FSH, LH, and SHBG increase significantly with advancing age 4
Clinical Interpretation Considerations
The remarkably wide interindividual variability (nearly 20-fold difference from lowest to highest values) means SHBG must be measured directly rather than assumed when interpreting testosterone levels. 2
Key Clinical Points
- SHBG binds testosterone with high affinity, reducing free testosterone availability for biological activity 1
- When evaluating hypogonadism, both total testosterone AND free testosterone (or free androgen index) must be measured, especially when SHBG abnormalities are suspected 5, 1
- A free testosterone index (total testosterone/SHBG ratio) <0.3 indicates hypogonadism 1
- Men with obesity frequently have low SHBG, which can result in normal free testosterone despite low total testosterone 5
Conditions That Alter SHBG
- Aging 2, 4
- Hyperthyroidism (SHBG serves as a marker of thyroid hormone action at tissue level) 3
- Hepatic disease 1
- Certain medications (anticonvulsants, estrogens, thyroid hormone) 1
- HIV/AIDS 1
SHBG decreases with: 1
- Obesity and insulin resistance 5
- Hypothyroidism 1
- Glucocorticoids, testosterone, anabolic steroids 1
- Acromegaly and Cushing's disease 1
Critical Clinical Pitfall
Relying solely on total testosterone without measuring SHBG can miss functional hypogonadism caused by elevated SHBG or falsely diagnose hypogonadism in obese men with low SHBG but normal free testosterone. 5, 1, 2 The pituitary primarily senses free testosterone rather than total testosterone when regulating the hypothalamic-pituitary-gonadal axis 1, making SHBG measurement essential for accurate assessment of androgen status 1.