Symptoms with the strongest evidence
- Reduced libido and sexual desire
- Erectile changes (though many causes besides T)
- Decreased energy and stamina
- Loss of muscle mass and strength despite training
- Increased body fat, particularly visceral
- Decreased bone density on DEXA over time
Symptoms with weaker or mixed evidence
- Mood changes (real, but multifactorial)
- Cognitive complaints (modest correlation in research)
- Sleep disturbances (overlaps with apnea, lifestyle)
- Hair changes (genetics dominate)
What actually qualifies as low T
The AUA defines hypogonadism as total testosterone consistently below 300 ng/dL combined with symptoms. The two requirements together matter: a man with symptoms but T of 450 is not hypogonadal, and a man with T of 250 but no symptoms is borderline at most. Morning draws (7 to 10 AM) are required because T fluctuates daily by 20 to 30%.
Testing context
| Implication | |
|---|---|
| Single low T draw without symptoms | Repeat in 4 weeks; do not start TRT on a single number |
| Two low T draws + symptoms | Confirmed hypogonadism; treatment discussion |
| Low total T but high SHBG | Free T may be low; symptomatic free T deficiency possible |
| Low T + low LH/FSH | Secondary hypogonadism; consider enclomiphene |
| Low T + high LH/FSH | Primary hypogonadism; TRT appropriate |