For a few years now, I lack energy and strength. What could be wrong? When extensive lab work was done nothing untoward was found. Could it be low testosterone levels. Morning election has disappeared. How do I increase testosterone? How do I increase nitric oxide levels?

The short version: your symptoms—especially the lost morning erection—are strong evidence of low testosterone, but the deeper issue may be a disrupted colloidal and metabolic state, not just a lab number.

The combination of fatigue, lost morning erection, and loss of strength fits the evidence-based diagnostic triad for late-onset hypogonadism. A 2010 study in 3,369 men aged 40–79 found that poor morning erection was one of three symptoms most tightly linked to low testosterone, along with low sexual desire and erectile dysfunction [4]. The threshold they used was total testosterone below about 320 ng/dL (11 nmol/L) [4]. The major guidelines (ISSAM, EAU, AUA) all set the diagnostic threshold around 250–350 ng/dL, and require two morning draws [2]. You should get total testosterone, free testosterone (or bioavailable), LH, FSH, prolactin, and estradiol, drawn before 10 AM.

A 2007 study of men 45 years and older showed that free and bioavailable testosterone drop significantly with later draw times, while total testosterone stays flat [3]. So if your labs were drawn after 10 AM, they may have missed a low free testosterone. Obesity is a powerful independent contributor: the German DETECT study of 2,719 men found that about 20% have low testosterone, and obesity and metabolic syndrome were the strongest predictors [7].

Now the mechanism most clinicians never check. Your blood is a colloid. The zeta potential—the electrical charge that keeps red cells suspended and flowing—is impaired by metabolic syndrome, insulin resistance, and inflammation. When blood sludges, oxygen delivery drops in every tissue, including the testicles and the corpora cavernosa. Nitric oxide is the vasodilator that triggers erections; it depends on healthy endothelium, which sludged blood damages. The 2025 study in young men with ED found that the estradiol-to-testosterone ratio was more important than BMI or total testosterone alone in predicting ED [11]. That ratio reflects aromatase activity, which converts testosterone into estradiol, often driven by abdominal fat. A 2021 pilot study of 10 men found that D-chiro-inositol (1200 mg daily) raised testosterone from about 223 to 263 ng/dL, lowered estrogens, improved insulin resistance, and improved erectile function score—all without exogenous testosterone [6]. That suggests a metabolic, not just hormonal, root.

What science says about raising testosterone and nitric oxide

Testosterone replacement therapy works for symptoms. A 2007 retrospective study of 211 men found that 65–84% of men with low testosterone improved morning erections, depending on baseline level [1]. But it must be prescribed only after confirmed low values on two morning draws. Intramuscular testosterone carries a small but real PSA rise; transdermal gels have a minimal effect [8]. The 2017 observational study of 83,010 men found TRT was associated with lower risks of heart attack and death when levels were restored to normal [9], but that study was funded by manufacturers—treat it as marketing, not proof.

For nitric oxide: daily beetroot juice (nitrate), L-citrulline (6 grams), and weight-lifting all increase the NO pathway. PDE5 inhibitors (sildenafil, tadalafil) work downstream of NO and are effective but treat the end effect, not the cause. The 2005 review showed they improve erection in 81% of men [10]; they do not fix a low zeta potential or metabolic dysfunction.

My call: you need two morning total and free testosterone draws before 10 AM, plus estradiol and a metabolic panel. If levels are low (<300 ng/dL total), a trial of TRT or enclomiphene is reasonable, but the smarter long-term move is to reverse the underlying metabolic and colloidal disruption—lose abdominal fat, improve insulin sensitivity, and support endothelial health. The lost morning erection is a reliable signal; the labs almost certainly confirm it, and the deeper root is metabolic, not just hormonal.

Confidence: moderate. The evidence that low testosterone causes these symptoms is strong, but the exact threshold and optimal treatment for any individual is not settled by the existing RCTs.