What we measure
This test looks for signs of health issues that can affect erectile function. As well as being influenced by mental health, erectile dysfunction can occur for a number of different reasons, including heart disease, diabetes, and a hormone imbalance. This test can help you figure out whether your symptoms are due to physical causes.
Total Cholesterol
High-density lipoprotein (HDL) cholesterol
High cholesterol is a risk factor for heart disease, which can lead to erectile dysfunction. HDL is known as “good” cholesterol because it helps remove other “bad” types from the body. High HDL can lower your risk of heart disease.
Low-density lipoprotein (LDL) cholesterol
Known as “bad” cholesterol, LDL can build up inside the walls of the arteries and cause them to narrow, making it harder for blood to pass through. This increases the risk of both heart disease and erectile dysfunction.
Non-HDL cholesterol
This is a calculation that tells you how much “bad” (LDL) cholesterol is in your blood. It’s done by subtracting HDL from the total amount of cholesterol present and this figure can be used to assess your heart disease risk.
Total cholesterol to HDL ratio
A calculation of how much “good” (HDL) cholesterol is in your blood, compared to your overall cholesterol level. To get the figure, you divide total cholesterol by HDL. This ratio can communicate your risk of heart disease: a higher ratio means a higher risk.
Thyroid function
Free T4
Free T4 is the main hormone produced by the thyroid gland and if its levels are abnormal, this may mean that the thyroid isn’t functioning properly. Thyroid issues cause hormonal imbalances that can bring on erectile dysfunction.
Thyroid-stimulating hormone (TSH)
When the thyroid produces too many or too few hormones, this can upset the body’s regular balance of hormones and affect sexual function. TSH tells the thyroid how many hormones to make, and if its levels are abnormal this can be a sign the thyroid isn’t working normally.
Diabetes
HbA1c
Having high blood sugar can cause damage to nerves and blood vessels over time, which may reduce blood flow to the penis. This can make it harder to get and stay erect. HbA1c is a measure of your average blood sugar level over the past three months.
Glucose
This is a measure of your blood sugar (glucose) level after a period of fasting. It can help indicate diabetes and whether your metabolism is working normally. Diabetes is a known risk factor for erectile dysfunction.
Prostate
Total prostate-specific antigen (PSA)
PSA is a protein made by the prostate gland. It’s normally present in low amounts but when it’s elevated, this can be a sign of health issues like prostatitis (swollen prostate gland) that can affect sexual function.
Hormones
Testosterone (total)
Testosterone is important for sexual function and libido. It plays a role in driving the body’s response to sexual stimulation, so if its levels are low this can have a dulling effect on your sex drive. Total testosterone measures the overall amount of the hormone in your blood.
Free testosterone
This is a measure of how much testosterone is actively working in the body—it’s “free” to do so because it isn’t attached to proteins. Erectile dysfunction has been associated with low free testosterone levels.
Sex hormone binding globulin (SHBG)
SHBG is a protein that attaches (“binds”) to hormones including testosterone. Once this happens, that hormone can’t be used by your body. SHBG levels can help us understand how much testosterone is bound and how much is available to be used.
Free androgen index (FAI)
FAI is a ratio that’s used to indicate whether you’ve got abnormal levels of male sex hormones (these are called androgens). It’s calculated by dividing total testosterone by SHBG, then multiplying by 100. This figure can tell you how much testosterone is actively working (free) in the body.
Prolactin
Prolactin, a hormone produced by the pituitary gland, is usually present at low levels in people assigned male at birth. When it’s elevated, this can cause a hormonal imbalance that affects sexual function.

This test can help indicate health issues that could affect erectile function.
Erectile dysfunction is defined as the inability to get and/or maintain an erection for long enough to have sex. It’s very common and happens to most people assigned male at birth at some point—but if it keeps happening over time, this can signal an underlying problem.
How we feel about sex—if we’re nervous or stressed, for example—can affect erectile dysfunction but there are also a number of physical explanations for it.
To become and stay erect, for example, there needs to be sufficient blood flow to the penis. Heart disease and diabetes can interfere with this. Throwing off the body’s regular, finely-tuned hormonal balance can also have a knock-on effect on sexual function.
This test can spot signs of health issues that can cause erectile dysfunction, to help you figure out what’s causing your symptoms.
Your results:
what to expect
In your results, you’ll receive a list of measurements that tell you how much of each substance is present in your blood, plus the calculations mentioned above, and whether these readings fall within a normal range.
A normal range is the amount you’d typically see within a healthy person.
If you have an abnormal reading, this signals that something inside the body isn’t working as it should be. This isn’t a diagnosis—only a doctor can diagnose you with a health condition. Rather, your results are a kind of status report that tells you what appears to be working well and what warrants closer investigation.
Blood tests one of the best tools we have for identifying health problems. Your doctor may use your results to inform their diagnosis, decide whether to do more tests, or help determine which treatments may help.

Need help? Speak with an expert
Don’t quite understand your results or simply want to see a doctor? We’ve got you sorted.
Speak to a GP
Book an online consultation with one of our GPs. We offer consultations in both English and Chinese.
Just fill out an online form and find a time that’s convenient.
Get a private prescription
Need to get your medication? Our GPs can write private prescriptions.
Tell the GP what the problem is during your consultation and they’ll take it from there. Prescriptions can be picked up at your local pharmacy.
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FAQs
Yes, this test requires a fasting sample, which means that you can’t eat or drink anything except water for 8-10 hours beforehand.
This test can tell you whether you may have a health issue that can cause erectile dysfunction. Only a doctor can diagnose you, but your blood test results can be used to inform their decision.
Blood tests are usually one of the first steps in investigating a health problem. They can uncover clear signs that something isn’t working as it should be, which can help doctors figure out what’s going on and whether to do any further tests.
Yes, this test is accurate in measuring the amount of each substance within your blood.
Our tests meet high standards for safety, quality, and best practice. We’re CQC registered, which is a quality mark for health services you can trust, UKAS accredited, and use advanced encryption to protect your medical information. Each test is validated by registered clinical scientists and doctors.
An abnormal reading may mean that you’ve got a health issue, so we’d advise speaking with a doctor about what your next steps should be. They can run more tests that confirm or rule out certain diseases, and then determine a treatment plan as necessary.
Usually, they will ask you questions about your medical and sexual history, including about your lifestyle, medications you’re taking, and your relationships. For example, they may ask how you would describe your levels of sexual desire, or how often you experience erectile dysfunction.
They will use these answers to try and determine what’s causing your symptoms and how best they can help you deal with them.
