Is Low Free Testosterone a Significant Cause of Erectile Dysfunction at Lower-Normal Levels?
Low-normal free testosterone is unlikely to be the primary cause of your erectile dysfunction, and psychological factors are more probable contributors when testosterone levels remain within the normal range. 1
Understanding Testosterone's Role in Erectile Function
Testosterone plays a supporting rather than primary role in erectile function. While a minimal threshold of testosterone is required for optimal erectile response, levels at the lower end of normal typically provide sufficient hormonal support for erections. 2, 3
The key distinction is this: Testosterone primarily regulates sexual desire (libido) and coordinates the timing of erections with sexual interest, rather than directly causing the mechanical erectile response itself. 2 The actual erectile mechanism depends predominantly on vascular and neurological factors—blood flow, smooth muscle relaxation, and nerve signaling—which function independently of testosterone once a baseline level is present. 3
Clinical Evidence on Testosterone Levels and ED
The 2018 AUA guidelines specify that testosterone deficiency is defined as total testosterone below 300 ng/dL with accompanying symptoms—not levels at the lower end of normal. 1 If your free testosterone is within the normal range, even at the lower end, this does not meet criteria for hypogonadism. 1
Importantly, the presence of morning and/or nocturnal erections strongly suggests a psychogenic component to ED symptoms that warrants further investigation. 1 If you experience erections during sleep or upon waking, this indicates that your erectile hardware (vascular and neurological systems) is functioning properly, pointing toward psychological rather than hormonal causes. 1
Psychological Factors as Primary Contributors
Multiple guidelines emphasize that psychological factors—including depression, anxiety, relationship conflict, and performance anxiety—are primary or secondary contributors to ED in most cases. 1, 4 The UK guidelines specifically identify clues to psychogenic ED: 1
- Sudden onset of symptoms
- Early collapse of erection during sexual activity
- Good quality spontaneous, self-stimulated, or morning erections
- Problems or changes in relationship dynamics
- Major life stressors
- Premature ejaculation or inability to ejaculate
If any of these patterns match your experience, psychological factors are likely the predominant cause. 1
When Testosterone Actually Matters for ED
Testosterone becomes clinically relevant for erectile function primarily in two scenarios:
- True biochemical hypogonadism (total testosterone <300 ng/dL with symptoms, particularly diminished libido) 1, 5
- Failure to respond to PDE5 inhibitors (medications like sildenafil/Viagra) in men with low testosterone 3, 6
Research shows that approximately 36% of men seeking consultation for sexual dysfunction have true hypogonadism, but this represents men with testosterone levels below the normal range. 5 Animal studies demonstrate that severe testosterone deficiency causes structural penile changes—smooth muscle atrophy, venous leakage, and collagen deposition—but these occur with profound deficiency, not low-normal levels. 3
The Multifactorial Reality of ED
ED is fundamentally a vascular condition and an early marker of cardiovascular disease. 1 The Princeton Consensus Conference identified ED as a substantial independent risk marker for cardiovascular disease, with predictive value equal to cigarette smoking or family history of heart attack. 1 This vascular component is far more commonly the organic cause of ED than hormonal factors. 1, 7
The 2025 European Association of Urology guidelines emphasize that most ED is multifactorial, involving organic (primarily vascular), psychological, and relationship components. 1 With low-normal testosterone, the hormonal contribution is minimal compared to these other factors. 1, 2
Recommended Diagnostic Approach
Rather than focusing on your borderline testosterone level, the appropriate evaluation should include: 1
- Assessment of morning/nocturnal erections (if present, strongly suggests psychogenic cause)
- Cardiovascular risk factor evaluation (blood pressure, glucose/HbA1c, lipids)
- Medication review (many drugs cause ED)
- Psychological screening for depression, anxiety, relationship issues
- Situational factors (does ED occur only with partners, only in specific contexts?)
Treatment Implications
First-line treatment for ED with low-normal testosterone should be PDE5 inhibitors (sildenafil, tadalafil, vardenafil), not testosterone therapy. 1 These medications are highly effective regardless of testosterone level, provided levels are not profoundly deficient. 1
The 2025 EAU guidelines explicitly recommend against testosterone therapy in men with normal testosterone levels (eugonadal men), even for sexual dysfunction, weight loss, or vitality concerns. 1, 5 Testosterone therapy in your situation would be inappropriate and potentially harmful, as it can cause erythrocytosis, cardiovascular risks, and permanent suppression of fertility. 1, 5
If PDE5 inhibitors fail and you have persistent symptoms with low-normal testosterone, then testosterone measurement becomes more relevant. 3, 6 Studies show that testosterone-deficient men who fail PDE5 inhibitor therapy may convert to responders with testosterone replacement, but this applies to men with true deficiency, not low-normal levels. 3
Psychosexual Therapy Consideration
Given that your testosterone is within normal range, psychosexual therapy should be considered as either primary treatment or adjunct to PDE5 inhibitors. 1 Success rates for psychosexual therapy range from 50-80% in motivated patients, and it can address underlying anxiety, relationship issues, and performance concerns that perpetuate ED. 1 This approach targets the more likely cause of your symptoms. 1, 4
Common Pitfall to Avoid
Do not assume that any testosterone level below mid-range requires treatment. 1, 5 Approximately 20-30% of men have testosterone in the low-normal range, but this represents normal physiological variation, not disease. 5 The critical error is treating symptoms with testosterone when the actual cause is psychological, vascular, or medication-related—this delays appropriate treatment and exposes you to unnecessary risks. 1, 5