What is a normal testosterone level for a man over 40?

Normal Testosterone Levels for Men Over 40

The normal range for testosterone in adult men over 40 is 300-800 ng/dL, with a level below 300 ng/dL considered a reasonable cut-off to support the diagnosis of low testosterone. 1, 2

Reference Ranges and Age Considerations

• The American Urological Association defines testosterone deficiency using a threshold of <300 ng/dL across all adult age groups 1
• The diagnosis of low testosterone requires both consistently low measurements (<300 ng/dL) and the presence of symptoms and/or signs 1
• Age-specific reference ranges show some variation, with men in their 40s typically having slightly higher levels than older men 3
• For men in their 40s, 50s, 60s, and 70s, the normal range (2.5-97.5th percentile) is approximately:
  • 40s: 251-914 ng/dL
  • 50s: 216-876 ng/dL
  • 60s: 196-859 ng/dL
  • 70s: 156-818 ng/dL 3

Proper Measurement Techniques

• The diagnosis of low testosterone should only be made after two total testosterone measurements are taken on separate occasions 1, 2
• Both measurements should be conducted in an early morning fashion (between 8-10 AM) when testosterone levels are naturally at their highest 1, 2
• Fasting morning testosterone levels provide the most accurate assessment 2

Clinical Implications of Testosterone Levels

• Testosterone deficiency in males is associated with:
  • Energy imbalance
  • Impaired glucose control
  • Reduced insulin sensitivity
  • Dyslipidemia
  • Increased abdominal fat mass
  • Reduced lean body mass 1, 2
• Symptoms most associated with testosterone levels ≤300 ng/dL include:
  • Sexual symptoms (decreased libido)
  • Psychological symptoms (decreased energy)
  • Physical symptoms (decreased strength or endurance, decreased ability to play sports, falling asleep after dinner) 4

Common Pitfalls in Testosterone Assessment

• Many men receive testosterone therapy without proper diagnosis - up to 25% of men who receive testosterone therapy do not meet the diagnostic criteria 1, 2
• Nearly half of men placed on testosterone therapy do not have their testosterone levels checked after therapy commences 1, 2
• When evaluating testosterone levels in men with obesity, measurement of morning serum free testosterone is essential, as obesity affects sex hormone-binding globulin levels 1
• Using a single measurement rather than two separate morning measurements can lead to misdiagnosis 1

Therapeutic Considerations

• For men on testosterone therapy, the target trough testosterone level should be maintained within the physiological range of 300-1,000 ng/dL 2, 5
• Clinical trials for testosterone replacement typically target middle-range values between 350-750 ng/dL 5
• Testosterone replacement in men with hypogonadism has demonstrated favorable results including improvements in fasting plasma glucose, insulin resistance, lipid profiles, and body composition parameters 1

Remember that the diagnosis of testosterone deficiency requires both consistently low testosterone levels AND the presence of symptoms/signs - the laboratory value alone is insufficient for diagnosis or treatment decisions 1, 2.