Understand your testosterone levels with a test that comes with clinician review. Heracles offers a straightforward first step, with results considered alongside your symptoms and health history.
This guide explains when to test, how to prepare and what the main hormone results mean. Start your Heracles testosterone test.
Take your sample in the morning, fasting and outside acute illness, following the collection instructions. A low result is repeated on a separate day. Your clinician uses your symptoms, medical history and related hormone results to decide what happens next.
Testing is most useful when symptoms or signs raise a reasonable suspicion of deficiency. These include reduced libido, fewer spontaneous erections, erectile dysfunction accompanied by other features, reduced body hair, small testes, infertility, gynaecomastia, hot flushes, low-trauma fracture or a combination of physical and psychological symptoms.
Testing may also be appropriate in selected conditions associated with hypogonadism, guided by a clinician. The European Association of Urology lists pituitary disease, testicular disorders, certain medicines, anabolic-steroid exposure, obesity, chronic disease and metabolic conditions among relevant causes or associations.
In men with a conventional sleep pattern, total testosterone should be measured in the morning. The joint UK position statement advises a morning, fasting sample and states that samples taken later than 11am should not be used to diagnose male hypogonadism. The EAU guideline specifies a morning window of 7am to 10am.
The reason is biological variation. Testosterone secretion follows a daily rhythm and is usually highest after sleep and earlier in the waking day, especially in younger men. A late sample can make a normal level look low.
Night-shift workers and men with disrupted sleep do not fit neatly into a clock-time rule. They should tell the clinician and laboratory about their sleep-wake pattern. Timing may need to be based on the biological morning after adequate sleep, but interpretation is less standardised and should follow the clinical protocol rather than an improvised home rule.
Yes, when the test is being used to diagnose testosterone deficiency under the UK joint position statement. Food intake can lower measured testosterone, so a non-fasting result may create a false impression of deficiency. Follow the laboratory's fasting instructions, which normally permit plain water.
Do not stop prescription medicines in order to “improve” the result. Record what you take and let the clinician decide whether a medicine affects testosterone or the assay. That includes opioids, glucocorticoids, testosterone, anabolic steroids, selective oestrogen receptor modulators, hCG, supplements and medicines affecting the pituitary or liver.
Acute illness can temporarily suppress testosterone. A test taken during a fever, significant infection, hospital admission or recovery from major illness may not represent the usual baseline. The UK position statement says measurements during acute illness should not be used to diagnose hypogonadism.
Other short-term factors can add noise, including marked sleep deprivation, extreme training, severe calorie restriction and a recent change in hormone or anabolic-steroid use. Do not manipulate normal life simply to obtain a higher result; provide the context so the clinician can decide whether to test now or repeat later.
Testosterone varies with sleep, food, illness and time of day. Repeating a low result on a different morning confirms whether it is persistent. Both samples should follow the same collection instructions before a treatment decision.
There is no single universal panel. A staged pathway often begins with total testosterone and adds tests according to the result and clinical question.
Total testosterone includes testosterone bound tightly to SHBG, testosterone bound more loosely to albumin and the small unbound fraction. It is the standard first biochemical test because it is widely available and better standardised than most direct free-testosterone assays.
The result is usually reported in nanomoles per litre in the UK. US websites commonly use nanograms per decilitre, which can cause confusion when readers compare thresholds without converting units or considering different guidance.
SHBG is a protein that binds testosterone. A high SHBG can make total testosterone look reassuring while calculated free testosterone is low. A low SHBG can make total testosterone look low even when the biologically available fraction is adequate.
SHBG may be altered by age, obesity, insulin resistance, thyroid disease, liver disease, certain medicines and other conditions. It is particularly useful when total testosterone is borderline or the clinical picture and total result do not match.
Albumin is another testosterone-binding protein. Total testosterone, SHBG and albumin can be used to calculate an estimate of free testosterone. Our guide to total testosterone, free testosterone and SHBG explains how these results fit together.
The Society for Endocrinology position statement makes an important distinction:
Direct free-testosterone immunoassays are often inaccurate. Equilibrium dialysis is the reference method but is not routinely available in UK practice. A result labelled simply “free testosterone” should therefore be interpreted with the laboratory method in mind.
LH and FSH show how strongly the pituitary is signalling the testes.
| Pattern | Possible interpretation |
|---|---|
| Low testosterone with raised LH, often raised FSH | Primary hypogonadism: the testes are not responding adequately |
| Low testosterone with low or inappropriately normal LH/FSH | Secondary hypogonadism: hypothalamic or pituitary signalling is inadequate, or the axis is functionally suppressed |
| Low testosterone with mixed or borderline gonadotrophins | Requires clinical interpretation; chronic illness, obesity, medicines and combined causes may blur the pattern |
FSH is also relevant to sperm production, but a hormone panel does not replace semen analysis when fertility is the question.
Raised prolactin can suppress gonadotrophin signalling, reduce testosterone and contribute to low libido or erectile dysfunction. It is particularly relevant when secondary hypogonadism is suspected, sexual desire is low or symptoms suggest a pituitary problem.
A raised result may need repeating under controlled conditions and investigating for medicines, stress, thyroid disease, macroprolactin or pituitary pathology. The required response depends on the value and symptoms.
Men produce oestradiol mainly by converting testosterone through the aromatase enzyme. Oestradiol is important for bone and sexual health. Testing may be appropriate in selected situations, such as gynaecomastia, certain fertility assessments or treatment monitoring, but it is not automatically required for every initial low-testosterone screen.
A broader assessment might include full blood count, thyroid function, glucose or HbA1c, liver and kidney markers, ferritin, lipids or other pituitary hormones. These do not diagnose low testosterone directly; they investigate alternative causes, associated conditions or treatment safety.
Before TRT, haematocrit, prostate risk and cardiovascular health require specific assessment. PSA testing depends on age, risk, symptoms and the shared decision with the clinician; it is not a universal add-on without context.
The UK Society for Endocrinology and laboratory-medicine position statement provides the following framework for symptomatic men tested correctly:
| Morning, fasting total testosterone | What it generally means |
|---|---|
| Below 8 nmol/L twice | Hypogonadism is likely; classify the cause and assess treatment suitability |
| 8–12 nmol/L | Can occur in eugonadal or hypogonadal men; interpret symptoms, SHBG and calculated free testosterone where indicated |
| Above 12 nmol/L | Not usually consistent with hypogonadism; one valid result above 12 nmol/L will usually exclude it |
The EAU uses below 12 nmol/L, repeated on at least two occasions in a symptomatic man, as a diagnostic threshold for late-onset hypogonadism. The greatest treatment benefits are generally seen in men with more marked biochemical deficiency.
UK reports usually use nmol/L; US reports often use ng/dL. Keep the original units and reference range when sharing a result. Your clinician can compare the reports and explain the result.
| Factor | Possible effect or problem |
|---|---|
| Late sampling | May read lower than a properly timed morning sample |
| Eating before the test | Can lower testosterone and complicate diagnostic interpretation |
| Acute illness | May temporarily suppress the hormonal axis |
| Poor or disrupted sleep | Can alter the daily rhythm and result |
| Obesity or insulin resistance | Often lowers SHBG and therefore total testosterone |
| Ageing, hyperthyroidism or some liver conditions | May raise SHBG and mask low calculated free testosterone |
| Opioids or glucocorticoids | Can suppress hypothalamic-pituitary signalling |
| Testosterone or anabolic steroids | Suppress natural LH, FSH and endogenous testosterone production |
| Assay or laboratory differences | Can shift results and reference ranges |
Document these factors so the result can be interpreted accurately.
Venous sampling is the established diagnostic route and allows enough material for a broader panel. Sample quality and laboratory handling remain important.
Capillary collection can make initial testing more accessible. Its suitability depends on the device, collection quality, analyte, transport conditions, laboratory validation and the clinical pathway. Your clinician confirms whether further testing is needed for diagnosis.
If an initial capillary result is low, borderline, unexpected or inconsistent with symptoms, confirmatory testing and clinical review are appropriate. Before testing, check which sample type is accepted at each stage rather than relying on a generic “highly accurate” claim.
Salivary testosterone is used in some research settings, but it is not the standard UK diagnostic test for adult male hypogonadism. A consumer saliva result should not be used to start TRT.
Your clinician reviews the collection conditions, repeats the test where needed and considers related hormones such as SHBG, LH, FSH and prolactin. Symptoms, medical history, fertility plans and treatment safety guide the next step.
If testosterone does not explain your symptoms, the review can identify other areas to investigate, such as sleep, thyroid health, anaemia or medication effects.
Monitoring is formulation-specific and should be prescribed, not improvised. The clinician needs to know when the sample was taken in relation to the injection, gel application or other dose. A level without that timing can be misleading.
The EAU recommends monitoring testosterone and haematocrit at three, six and 12 months after starting treatment and annually thereafter, with closer checks in men at higher risk of raised haematocrit. PSA, symptoms, blood pressure and metabolic factors may also need monitoring based on age and risk.
Already on TRT? Start with the results you have. Heracles offers a free switch consultation. Your clinician reviews your existing reports and explains whether any further testing is needed.
To help the team review your care, gather:
A blood test taken during TRT helps monitor treatment; it does not show your untreated baseline. Sample timing also depends on the medicine used. Share that context with your clinician and keep following your current prescriber’s instructions. Read the EAU guidance on assessment and monitoring.
Heracles checks the age of the reports, the markers measured and their suitability for your transfer. The team will explain any extra tests and their price before payment. Ask for the secure record-sharing route when you enquire.
Heracles was co-founded by Professor Suks Minhas and Professor Tet Yap. Our clinical team brings together expertise in urology, andrology, endocrinology and nutrition. Meet the team behind your care.
Injectable plans start from £105 per month, including prescribed TRT medication, applicable supplies, scheduled blood tests and doctor reviews. Your switch consultation is free. Plans are billed monthly with a three-month minimum; extra testing, hCG and additional services are priced separately.
Enquire about your free switch consultation, or follow our step-by-step guide to switching TRT clinics.
Follow the kit’s timing and fasting instructions, tell the team about medicines and supplements, and flag recent illness or disrupted sleep. Keep taking prescribed medicines unless your prescriber advises otherwise. If you are on TRT, confirm the correct sampling time relative to your dose.
Check your testosterone with Heracles.
Yes, but it becomes a monitoring test rather than a baseline diagnostic test. The correct timing depends on the formulation and dosing schedule, so follow the prescriber's instructions.
Low SHBG can produce that pattern, often in obesity or insulin resistance. It may argue against true androgen deficiency, but the clinician must review the assay, calculation, symptoms and wider health picture.
The symptoms remain valid. A normal testosterone result should redirect the assessment towards other causes rather than trigger treatment to push testosterone above the physiological range.
