Low testosterone symptoms: diagnosis and when to treat (and when not to)
Which symptoms really point to low testosterone, how it is confirmed with blood tests, what has evidence behind it and what we now know about its safety.
5 min readEducational content by RejuvelookUpdated in October 2026
In short
Low testosterone is only a medical problem when matching symptoms, mainly sexual ones, coincide with low levels confirmed on more than one early-morning blood test. Before treating, the cause has to be found, and excess weight is one of the commonest. In men with a confirmed deficiency, hormone treatment improves sexual function and needs monitoring.
Key points
- In a European study of 3,369 men, the symptoms most closely tied to low testosterone were sexual: fewer morning erections, low desire and erectile dysfunction.
- Diagnosis needs symptoms plus low levels confirmed on repeat fasting blood tests taken in the morning.
- Weight loss comes first in men who are overweight; in severe obesity the deficiency resolved in 87% after bariatric surgery.
- Recent large trials show no rise in cardiovascular risk in the short to medium term with properly indicated hormone treatment.
- With normal levels, hormone treatment is not a booster: there is no clear benefit and there are real risks.
Tiredness, low sex drive or a sense of having lost your edge lead many men to wonder about their testosterone. Sometimes that is the answer. Often the cause lies in sleep, weight, stress or general health. This guide explains how to tell the difference, and how low testosterone is assessed if you live in Spain.
What low testosterone is (and why "andropause" misleads)
Testosterone falls gradually with age, and not equally in every man. That is why "andropause" is a misleading word: there is no sudden switch-off like the menopause. What doctors call hypogonadism is the combination of low testosterone and related symptoms [5].
There are two broad types. Organic hypogonadism comes from a genuine problem in the testes or the pituitary gland, and is diagnosed and treated with little debate. Functional hypogonadism appears without such damage, alongside obesity, type 2 diabetes, illness or age itself. Here, improving overall health remains the reference strategy [4].
Which symptoms actually point to it
The European Male Ageing Study (EMAS) looked at 3,369 men aged 40 to 79 in eight centres. Many symptoms were linked to testosterone, but only three formed a clear pattern with low levels: fewer morning erections, low sexual desire and erectile dysfunction [1].
Fatigue, low mood and reduced stamina are common but non-specific. They may come from testosterone, or from a long list of other causes. Symptoms point the way; they do not make the diagnosis.
How it is diagnosed
A sound diagnosis follows clear steps:
- An early-morning, fasting blood test, because levels vary through the day. A low result is repeated to confirm it [2].
- Reading the numbers in context. In EMAS, the criteria were at least three sexual symptoms, total testosterone below 11 nmol/L (about 320 ng/dL) and free testosterone below 220 pmol/L [1]. Cut-offs vary a little between guidelines and labs.
- Looking for the cause, with other hormones when relevant, and ruling out organic problems [2].
- Reviewing your medication, because some medicines lower testosterone production and changing them is sometimes enough [2].
If you want the vascular side of sexual health, our guide to erectile dysfunction covers it.
What has evidence behind it
General health comes first. In men who are overweight or obese, European guidelines put lifestyle change and weight loss as the first step [2]. This is not a footnote: in one meta-analysis, 64% of men with severe obesity had an obesity-related hormone deficiency, and it resolved in 87% after bariatric surgery and the major weight loss that follows [6]. Our guide to medical weight loss in Spain explains how that is approached.
When the deficiency is confirmed and there are symptoms, hormone treatment improves sexual function, though modestly [4]. Other benefits often claimed for it, such as more energy, better mood or more muscle, remain uncertain [2]. The 2025 European urology guidelines stress getting the indication right and following patients up [3].
What the evidence says
Each statement shows its level of evidence and the sources behind it.
Supported
- Diagnosis requires compatible symptoms and low testosterone confirmed on repeat early-morning tests, after ruling out an underlying organic cause.[1][2]High-quality evidence
- In men who are overweight or obese, lifestyle change and weight loss come first, and can correct the deficiency.[2][4][6]High-quality evidence
With caveats
- In confirmed deficiency, hormone treatment modestly improves sexual function; other claimed benefits such as energy, mood or muscle remain uncertain.[2][4]Moderate evidence
- Recent large trials show no increase in cardiovascular or prostate cancer risk in the short to medium term with properly indicated treatment; long-term data are still lacking.[4][5]Moderate evidence
Not enough support
- Hormone treatment with normal levels to boost energy, performance or muscle: no evidence of benefit and clear risks.[2]Low-quality evidence
Heart safety: what we have learnt since 2023
For years the main worry was the heart. Over the past decade, several large trials, including one published in 2023 in men at high cardiovascular risk, and an individual patient data meta-analysis have clarified the picture. In men with functional hypogonadism, treatment did not increase cardiovascular or prostate cancer risk in the short to medium term [4].
That does not make it harmless. Long-term data are still missing, and recent international consensus still calls for case-by-case decisions and close monitoring [5].
What to expect, realistically
If the deficiency is linked to excess weight, poor sleep or a medicine, correcting the cause may be enough, although it takes months. In severe obesity, the major weight loss after bariatric surgery raised total testosterone by an average of 8.1 nmol/L (about 230 ng/dL) [6].
If hormone treatment is started, the improvement to expect is mainly in sexual function, and it is modest [4]. It will not turn the clock back, and it does not replace exercise or rest. The guidelines ask doctors to discuss benefits and uncertainties openly and decide together [2]. So from the outset you agree which symptom you want to improve and when it will be reviewed.
Risks, and who it is not for
Hormone treatment is ruled out with untreated prostate or breast cancer, or severe heart failure. A high haematocrit, above 48 to 50%, or significant urinary symptoms call for real caution [2]. In men over 40, the prostate is checked before starting [2].
If you want children, conventional hormone treatment is not the right choice; there are alternatives designed to protect fertility [2].
And it is not a booster. With normal levels there is no clear benefit and there are real risks. Hormones sold in gyms or online, without a diagnosis or monitoring, are a genuine health hazard.
How it works at Rejuvelook
We see men's hormonal health online anywhere in Spain, discreetly and in English or Spanish. It starts with a medical video consultation. If appropriate, the doctor requests an early-morning blood test at a lab near you and confirms any low result.
With the results, the doctor looks for the cause and explains your options: lifestyle change, treatment when it is indicated, or referral to urology or endocrinology if your case needs it. Any treatment is prescribed with a Spanish e-prescription and followed with regular checks, and your reports are available in English for your GP at home.
We do not prescribe hormones without a confirmed diagnosis, and never as a booster.
When to see a doctor
Book a medical consultation, or go to A&E if it is severe or sudden, if you notice:
- Chest pain, breathlessness or palpitations, especially on exertion: go to A&E (urgencias, or call 112), do not wait for an appointment.
- Shrinking testicles, breast enlargement or a lump in a testicle.
- Persistent headaches or changes in your vision together with loss of sex drive.
- If you already use hormones obtained without a prescription: do not stop abruptly on your own, but get advice soon.
Frequently asked
Can I be seen in English?
Yes. Consultations, consent forms and reports are available in English, which also makes it easy to share your results with your GP at home.
I already have results from the UK. Can I use them?
Yes, as a starting point. UK labs report testosterone in nmol/L, while many Spanish labs use ng/mL or ng/dL; the doctor converts between them. If the test was not taken in the morning, fasting, or was a single reading, it is usually repeated before any decision.
I am already on hormone treatment prescribed at home. Can you take over?
Bring your records and recent results. The doctor reviews how the diagnosis was made and how it has been monitored, then decides whether continuing is appropriate and how follow-up will work in Spain.
Is it confidential?
Yes. Your health data are handled with reinforced confidentiality and only with your explicit consent. The consultation is between you and the doctor.
I may want children in future. Does that matter?
A great deal. Say so from day one. If fatherhood is on the cards, the approach changes and the guidelines reserve different options to protect fertility.
What monitoring is needed if I start treatment?
Regular blood tests to check the levels reached and your haematocrit, a prostate check (PSA) if you are over 40, plus blood pressure and symptoms. The doctor sets the schedule.
Does it work if I spend part of the year outside Spain?
Reviews continue by video call. Prescriptions are Spanish e-prescriptions dispensed in Spanish pharmacies, so time away is planned before you travel.
References
Sources checked against PubMed or Crossref. Cited as plain text, without links.
- 1.Wu FC, Tajar A, Beynon JM, Pye SR, Silman AJ, Finn JD, et al. Identification of late-onset hypogonadism in middle-aged and elderly men. N Engl J Med. 2010;363(2):123-35. doi: 10.1056/NEJMoa0911101. PMID: 20554979.Verified on 2 October 2026
- 2.Corona G, Goulis DG, Huhtaniemi I, Zitzmann M, Toppari J, Forti G, et al. European Academy of Andrology (EAA) guidelines on investigation, treatment and monitoring of functional hypogonadism in males: Endorsing organization: European Society of Endocrinology. Andrology. 2020;8(5):970-987. doi: 10.1111/andr.12770. PMID: 32026626.Verified on 2 October 2026
- 3.Salonia A, Capogrosso P, Boeri L, Cocci A, Corona G, Dinkelman-Smit M, et al. European Association of Urology Guidelines on Male Sexual and Reproductive Health: 2025 Update on Male Hypogonadism, Erectile Dysfunction, Premature Ejaculation, and Peyronie's Disease. Eur Urol. 2025;88(1):76-102. doi: 10.1016/j.eururo.2025.04.010. PMID: 40340108.Verified on 2 October 2026
- 4.De Silva NL, Papanikolaou N, Grossmann M, Antonio L, Quinton R, Anawalt BD, et al. Male hypogonadism: pathogenesis, diagnosis, and management. Lancet Diabetes Endocrinol. 2024;12(10):761-774. doi: 10.1016/S2213-8587(24)00199-2. PMID: 39159641.Verified on 2 October 2026
- 5.Khera M, Torres LO, Grober ED, Morgentaler A, Miner M, Jones TH, et al. Male hypogonadism: recommendations from the Fifth International Consultation on Sexual Medicine (ICSM 2024). Sex Med Rev. 2025;13(4):548-573. doi: 10.1093/sxmrev/qeaf036. PMID: 40862363.Verified on 2 October 2026
- 6.Escobar-Morreale HF, Santacruz E, Luque-Ramírez M, Botella Carretero JI. Prevalence of 'obesity-associated gonadal dysfunction' in severely obese men and women and its resolution after bariatric surgery: a systematic review and meta-analysis. Hum Reprod Update. 2017;23(4):390-408. doi: 10.1093/humupd/dmx012. PMID: 28486593.Verified on 2 October 2026
Educational content. It does not replace a medical consultation or provide a diagnosis. Tests and treatments are indicated only after medical consultation and in line with regulation.