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Erectile difficulty: what the bloods can tell you

Headshot of Dr. Nikola Topalovic, MD PhD
Medically reviewed by Dr. Nikola Topalovic, MD PhD · Last reviewed 4 September 2026

Erectile difficulty is treated as a hormone problem far more often than it is one. In men under 60 it is frequently vascular or metabolic — and that makes it an early warning worth investigating properly rather than an embarrassment to work around.

What people notice

  • Reduced or absent morning erections
  • Difficulty maintaining rather than achieving
  • Onset alongside weight gain, rising blood pressure or poor sleep
  • Reduced libido as well as function
  • New difficulty after starting a medication

Symptoms overlap between causes. This list is a prompt to measure, not a diagnosis.

Markers worth measuring

Total and free testosterone
Worth measuring, but a normal result does not exclude a cause — and low libido tracks hormones more closely than erectile function does.
Prolactin
Elevated prolactin causes both low libido and erectile difficulty and is a specific, checkable finding.
HbA1c and fasting insulin
Diabetes and insulin resistance damage the small vessels and nerves involved. This is one of the most common underlying causes.
Full lipid profile and ApoB
Penile arteries are small; endothelial dysfunction shows there before it shows in the coronaries.
TSH, free T4, free T3
Both underactive and overactive thyroid affect sexual function.
Full blood count, liver and kidney function
Systemic disease and anaemia both contribute and are easily excluded.
Vitamin D and ferritin
Common deficiencies that affect energy, mood and libido.

The vascular signal. The arteries supplying the penis are considerably narrower than the coronary arteries, so endothelial dysfunction becomes symptomatic there first. Studies consistently find erectile difficulty preceding a cardiac event by several years in men with vascular disease. That is precisely why a full metabolic and lipid picture belongs in the work-up, not just a testosterone level.

Why morning erections matter to the history. Their presence suggests the vascular and neurological machinery is intact and points towards psychological or situational factors; their absence points towards a physical cause. It is a crude signal, not a test, but it usefully shapes what to look at first.

Medication and lifestyle contributors. Several common medication classes affect erectile function, as do alcohol, smoking, untreated sleep apnoea and poor sleep generally. None of these show up on a hormone panel, which is why the results are read alongside a proper history rather than in isolation.

Scope. FORM measures and explains — we do not prescribe or supply any treatment for erectile difficulty. If function has changed, see a doctor registered where you live; comprehensive bloods make that appointment considerably more productive.

FAQs

Is erectile difficulty usually caused by low testosterone?
Less often than assumed. Low testosterone affects libido more than mechanical function; vascular, metabolic, medication and psychological causes are collectively more common.
Why check heart risk markers?
Because the penile arteries are small and show endothelial dysfunction early. Erectile difficulty can be the first sign of cardiovascular disease years before other symptoms.
Does one panel settle the cause?
No. Bloods rule in and rule out the systemic contributors. The rest comes from a clinical history and examination with your own doctor.
Does FORM provide treatment?
No. We are a pathology testing service. We measure and explain the results; treatment decisions belong to a registered doctor where you live.

Measure it properly, in one morning draw.

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