Erectile dysfunction tests and diagnosis: getting to the bottom of your erection issues

Written with
Dr Matthew Chan

If you’re like us, the word ‘tests’ probably gets your mind racing. This can put us off getting to the bottom of our erection issues, and may send us into a downward spiral of worry.

So, before we begin, we want you to know that in most cases, getting an ED diagnosis is a pretty straightforward process. You’ll probably only need a small handful of the tests we talk about in this post. Often a quick chat, followed by a few basic tests (and maybe a physical exam), are all that’s needed to tell your doctor what’s going on.

But here at Mojo HQ, we like to be thorough. So we’ve worked with medical doctor Matthew Chan to create a mega list of how ED is diagnosed and tested. We’ve covered all the bases, so you can feel ready to make the move to next base.

Before we begin: ED diagnosis 101

There are many causes of ED, and they can be both physical and psychological. To make things more complicated, when you have a physical root cause of ED, you will also likely have psychological components to your issue. This is because it can get into your head and knock your confidence.

To get a proper diagnosis for ED, you should explore both possibilities, so you can put together a treatment plan that’s tailored to your specific needs.  

No one should have to face ED alone. And when it comes to getting a diagnosis, a qualified doctor is the best starting point to help you in your quest.

Here’s a summary of how you can help them help you:

1. Answer questions and give a medical/sexual history low-down

Questions may include details about your experience with ED, lifestyle, general health, medical history, and mental health.

This will help them form a picture of how your body and mind are working, and identify what could be putting them under unusual stress.

You can delve more into the questions that your doctor may ask you (as well as questions you may want to ask your doctor) here.

2. Fill out an ED questionnaire

If you turn up to your doctor’s appointment with a completed copy of the IIEF (International Index of Erectile Function) questionnaire, you’ll have given them a good starting point.

Don’t sweat if you can’t or don’t have time though – your doctor will make sure they get all the info they need and talk you through the next steps.

3. Run through some ED tests

Your doctor will want to carry out some tests to identify any potential physical issues (such as diabetes or heart issues) that might be leading to your ED.

If physical causes have been ruled out, then it’s likely that you’re experiencing psychological erectile dysfunction.

4. Refer you to a specialist if needed

If physical erectile dysfunction is suspected, you may be referred to a specialist such as a urologist or physiotherapist.

If psychological ED is a prime suspect, you may be referred to a specialist like a psychosexual therapist or psychiatrist.

For any lifestyle changes needed, you may be referred to a specialist such as a lifestyle coach or nutritionist.

Being referred to these specialists will allow you to carry out any further tests if needed, and get you started on the most suitable treatment plan. You’ll be on your way to getting better erections.

Can tests for ED reveal other health issues?

It’s true: ED can be a warning sign of other conditions, especially as we grow older. But that doesn’t mean there’s always something bigger going on.

It’s just another reason why it’s so important to listen to what your body is telling you and always get the advice, tests, and support you need.

Read on to find out more about the tests available (and more importantly, what each test is for).

Physical exams for erectile dysfunction

These checks for physical ED won’t necessarily be carried out by every doctor. But depending on the questions and answers covered, your physician may feel like a physical exam is needed. This may include:

  • General health and wellbeing checks

These include blood pressure and pulse rate checks. These might give subtle hints to the doctor of any underlying issues that might be related to your ED or generally affecting your health.

  • Penis checks

This exam looks for things like phimosis (where the foreskin is too tight), Peyronie’s disease (where the penis is curved when erect), or other abnormal changes (such as an injury) that could be causing erectile dysfunction.

  • Other physical checks

A thorough doctor may also look at your hands, face, chest, abdomen, and listen to your heart to look for general signs of conditions like heart disease and diabetes that can cause ED.

Blood test panel for physical causes of ED

Moving onto one of our favorite topics: bodily fluids (nothing sexy this time).

Our blood is packed full of information that can be helpful to cross off some important physical causes of ED.

When it comes to venous sampling, a needle is inserted into a vein to collect a sample of blood (those with weaker dispositions, look away at this point).

We’ve listed these venous blood tests below. You can ignore the fancy names and skip to the part about what doctors are actually looking for when they send your red stuff off to the lab.

Serum testosterone level (hormone test)

  • This tests for: Low testosterone
  • What to expect: Typically done in the morning when testosterone levels are at their highest, as low testosterone can be a cause of ED

Thyroid (T3, T4, TSH) function (hormone tests)

  • This tests for: Thyroid issues
  • What to expect: Measures thyroid hormone levels in the blood; abnormalities may indicate a disturbance that can relate to ED

Serum prolactin level (hormone test)

  • This tests for: Prolactin levels
  • What to expect: Prolactin is a hormone produced in the pituitary gland; if too much is produced, this can lead to ED. This test is usually done in the morning when prolactin levels are at their highest. This test is very rarely needed

Full blood examination (FBE)

  • This tests for: Anemia
  • Also known as: Full Blood Count (FBC) or Complete Blood Count (CBC)
  • What to expect: Measures red blood cell count (carries oxygen), white blood cell count (fights intruders), and platelet levels (helps blood to clot) in your blood. If red blood cell levels are low, this could indicate anemia, which may be a cause of ED

Fasting blood glucose test

  • This tests for: Diabetes
  • What to expect: Usually done after not eating overnight to check your ‘lowest’ blood sugar levels. If these are low, it could be a sign of diabetes – an underlying cause of erectile dysfunction
  • Alternatives: Random blood glucose test (done at any time to check blood sugar level) or HbA1c test (a blood marker that gives an idea of sugar levels over the last three months)  

Fasting lipids test (cholesterol levels, triglyceride levels)

  • This tests for: Heart disease, such as atherosclerosis (a cholesterol plaque buildup in blood vessels)
  • What to expect: Usually done after not eating overnight to get an accurate measure. If lipid levels are high (especially certain subtypes like LDL), this could be a sign of atherosclerosis, which can affect blood flow to the penis

Serum creatinine level test

  • This tests for: Kidney disease
  • What to expect: Measures creatinine levels in the blood; the higher the creatinine level, the worse your kidneys are at filtering your blood – which can lead to ED (but this is uncommon)

Depending on the assessments carried out, as well as your age, many of these won’t apply to you. Your doctor will advise you which ones you need (if any at all).  

Testing yourself for erectile dysfunction

We would always recommend going to a qualified professional – like your doctor – to carry out any ED tests in the most safe and reliable way.

But, we understand that for obvious reasons, a lot of men would prefer to test themselves from the privacy of their bedrooms. These ED self tests can include:

Home blood testing kits

You can order these online, but if you go down this road, please make sure you do your homework and choose a trustworthy provider (it’s worth comparing prices, too).

These kits usually involve collecting blood from your fingertip into a tube, and then sending this off to a lab (a finger-prick test is less invasive but can also be less accurate).

Your best bet is leaving this to the doctor. As well as performing the blood tests, they’ll be able to factor in your personal circumstances and give you a lot of supporting wisdom that you’ll miss out on by doing it yourself.

The stamp test

This involves sticking an old-fashioned roll of stamps around your penis at night. We’ve not made that up, we promise.

If the chain is broken when you wake: hey, you might have had an erection. Or just rolled over. Hard to tell.

For these reasons (and the sheer difficulty of getting hold of stamps that went out of production in the ’80s), we reckon the stamp test is nothing to write home about.

Overnight erection tests

Some ED tests may involve checking for your nighttime erections. If you get an erection in the night (or notice you have morning erections), this can sometimes be a reassuring sign that your penis is in good physical working condition.

However, important newsflash! Some people don’t notice that they’ve had a boner every single night or every single morning, and that doesn’t mean there’s something wrong with them.  

This fact alone is a good reason to be slightly skeptical of tests that rely on monitoring the nighttime wanderings of your penis.

But when we said complete list, we meant it. So here you go:

The nocturnal penile tumescence (NPT)

This test is something that can be done at home or in a sleep lab.

It uses two stretchy rings connected to an electronic device to track nocturnal erections from the base of the penis and just under the head.  

Clinicians only use the NPT test in very unclear cases, so it really isn’t something we would recommend as a first port of call. If your doctor thinks you’re in that camp, they will tell you.

The Stamp Test falls under this category too. It’s a version of the NPT test – but we wouldn’t lose sleep over this one.

Advanced tests for ED

They’re rarely needed, but it can be reassuring to know there are a bunch of great specialists out there who can investigate your ED further, if it’s tricky to diagnose at first.

Electrocardiogram (ECG)

If an initial blood test flags potential heart problems, more tests may be carried out, such as an ECG. This is where electrodes are placed on the chest and limbs measuring heart electrical activity. This can flag abnormal rhythms or heart function.

Bulbocavernosus reflex

A physical exam that tests the nerve function to your penis. This gives your doctor an idea if there’s any disruption to the nerve connections from the brain to the penis (these disruptions could be caused by any neurological condition or injury).


Sometimes performed with an injected dye to check blood flow to and in the penis. And good to keep after as psychedelic wall art.


A non-invasive test that uses sound waves to check the penis for tissue scarring and to measure the blood flow. If there’s impaired blood flow to or from the penis, this could be a cause of ED.

Venous leak tests

If the veins in your penis can’t hold the blood there during an erection, you’ll lose it. This is known as venous leak, and there are a few tests that can help identify and understand it:

  • Dynamic infusion cavernosometry where fluid is pumped into the penis to measure how severe the leak is
  • Cavernosography where dye is injected into the penis so it can be X-rayed, revealing venous leak or damaged arteries

Mojo has your back

If you do rule out physical causes of your issues, Mojo has expert-led content to help you get better erections.

We’ve put a whole fleet of sexual health experts to work, creating a raft of content to share their knowledge with you in bite-sized chunks that help you make real improvements day by day.

If you’d like more support, our Community is here and always open. You’ll find other guys asking a lot of anonymous questions and sharing experiences that might make you go: “oh yeah, me too.”

Mojo aims to provide useful wellbeing resources to its users; however, you should not solely rely on opinions or advice available on the Website or given by the Community. Always seek advice from a qualified medical doctor or other healthcare professional before acting.

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