Low testosterone is both under-diagnosed in men who genuinely have it and over-diagnosed in men who do not. The reason is that its most talked-about symptoms – tiredness, low mood, poor concentration, reduced muscle – are non-specific and have many other causes.
Two facts cut through most of the confusion. First, a diagnosis requires symptoms and consistently low levels, not a number on its own. Second, about 30% of men with an initial low reading have a normal result when the test is repeated, which is why a single sample settles nothing.
This guide covers which signs actually point to low testosterone, how the test must be done to be meaningful, and what else is checked alongside it.
The Signs, Ranked by How Specific They Are
The Endocrine Society’s clinical practice guideline groups symptoms by how strongly they point to testosterone deficiency. The distinction is useful, because the symptoms people usually search for sit in the weakest group.
More specific signs
- Incomplete or delayed sexual development
- Loss of body hair
- Very small testes (under 6 mL)
Suggestive signs
- Reduced libido or sexual activity
- Fewer spontaneous erections, or erectile dysfunction
- Breast discomfort or enlargement (gynaecomastia)
- Infertility or a low sperm count
- Loss of height, low-trauma fracture or low bone density
- Hot flushes or sweats
Non-specific signs
- Low energy or motivation
- Low mood
- Poor concentration or memory
- Disturbed sleep
- Mild unexplained anaemia
- Reduced muscle bulk, increased body fat
Why this ranking matters: the non-specific group overlaps almost entirely with thyroid disorders, anaemia, Vitamin D and B12 deficiency, poor sleep, depression, chronic stress and untreated sleep apnoea. Fatigue alone is a weak reason to assume low testosterone, and a strong reason to test more broadly.
How the Test Must Be Done
Testosterone is one of the easiest tests to get wrong, because the result depends heavily on timing and conditions.
Morning sample, after an overnight fast
Testosterone follows a daily rhythm, peaking in the morning. The guideline specifies measuring total testosterone in the morning after an overnight fast, because food and glucose intake suppress levels. An afternoon sample taken after lunch can read low in a man whose levels are entirely normal.
Two separate mornings
A diagnosis needs the measurement repeated on two separate mornings. The guideline notes that roughly 30% of men with an initial result in the hypogonadal range are normal on repeat.
Not during acute illness
Testosterone falls temporarily during acute illness and with short-term use of certain drugs, including opioids. Testing during these periods produces a misleading low result.
Assay quality matters
The guideline recommends an accurate, reliable assay, ideally one certified by a recognised standardisation programme.
Stop biotin beforehand
High-dose biotin, common in hair and nail supplements, interferes with several hormone immunoassays. The guideline advises stopping biotin for at least 72 hours before LH and FSH testing. Tell the lab everything you take.
Total vs Free Testosterone
Total testosterone measures all the testosterone in your blood, most of which is bound to proteins, chiefly sex hormone-binding globulin (SHBG).
Free testosterone is the small unbound fraction. It is measured or calculated when the total result is ambiguous or when SHBG is likely to be abnormal.
The guideline advises measuring free testosterone when:
- Total testosterone is near the lower limit of normal, roughly in the 200 to 400 ng/dL range, or
- A condition is present that alters SHBG – obesity, diabetes, ageing, HIV, or oestrogen use
On method: free testosterone should be measured by equilibrium dialysis, or calculated from total testosterone, SHBG and albumin. The guideline advises against direct analog-based free testosterone immunoassays, which it describes as inaccurate. This is worth asking your lab about, because the cheaper direct assay is widely used.
What Else Gets Tested
A low testosterone result is the start of an assessment, not the end of one.
LH and FSH are measured to determine where the problem lies:
- Primary hypogonadism – the testes are not producing enough, and LH and FSH are high as the body tries to stimulate them
- Secondary hypogonadism – the signal from the pituitary or hypothalamus is inadequate, and LH and FSH are low or inappropriately normal
This distinction changes the entire investigation. For secondary hypogonadism, the guideline advises measuring prolactin and iron studies (iron saturation and/or ferritin), since a prolactin-secreting pituitary tumour and haemochromatosis are both identifiable causes.
Other investigations the guideline describes in specific situations:
- Karyotype for primary hypogonadism of unknown cause, particularly with very small testes
- Pituitary MRI for severe secondary hypogonadism, persistent high prolactin, panhypopituitarism, or symptoms suggesting a tumour
- Semen analysis, at least two samples several weeks apart, where fertility is a concern
Because the non-specific symptoms overlap so heavily, a doctor will usually also check thyroid function, a complete blood count, Vitamin D and B12, blood sugar and a lipid profile before attributing fatigue to testosterone.
Why Routine Screening Is Not Recommended
The Endocrine Society guideline recommends against routine screening of men in the general population for hypogonadism. It also suggests clinicians avoid using case-finding questionnaires in men who are seeking care for unrelated reasons.
Testing is instead suggested for men with specific conditions, including low libido, erectile dysfunction, infertility, HIV-associated weight loss and osteoporosis.
This is the opposite of how testosterone testing is often marketed. A testosterone test added to a general wellness panel for a man with no relevant symptoms is likely to generate either a false alarm or false reassurance, not useful information.
Conditions That Lower Testosterone
Before concluding that the testes or pituitary are at fault, several reversible contributors are worth examining:
- Obesity, which both lowers testosterone and alters SHBG
- Untreated obstructive sleep apnoea
- Type 2 diabetes and metabolic syndrome
- Chronic opioid use, and long-term glucocorticoids
- Excess alcohol
- Chronic illness of almost any kind
- Severe sleep deprivation and prolonged stress
- Anabolic steroid use, past or present, which suppresses the body’s own production and is frequently not disclosed
Addressing these can change the picture substantially, and sometimes removes the need for any hormone treatment.
A Note on Testosterone Therapy
Testosterone therapy is a prescription medical treatment with a defined set of indications, monitoring requirements and contraindications. It is not a supplement, and it is not something to start on the basis of a single online test result or an over-the-counter “booster”.
Men diagnosed with hypogonadism are managed and monitored by a doctor, typically an endocrinologist or urologist. Anyone considering treatment should have the diagnosis properly established first – which means the morning sample, repeated, with LH, FSH and the relevant follow-up tests.
Frequently Asked Questions
1. Which test is done for low testosterone?
Total testosterone measured in a morning sample after an overnight fast is the primary test. It must be repeated on a second separate morning to confirm. Free testosterone, LH and FSH are added depending on the result, and prolactin and iron studies are checked where the problem appears to originate above the testes.
2. What time of day should a testosterone test be done?
In the morning, after an overnight fast. Testosterone follows a daily rhythm and peaks in the morning, and food and glucose intake suppress levels. An afternoon sample taken after a meal can read low in a man with entirely normal levels.
3. Does one low testosterone result mean I have a deficiency?
No. A diagnosis requires symptoms or signs of testosterone deficiency together with consistently low levels on two separate morning samples. The Endocrine Society guideline notes that about 30% of men with an initial low result have a normal result when retested.
4. What is the difference between total and free testosterone?
Total testosterone measures all testosterone in the blood, most of it bound to proteins. Free testosterone is the small unbound fraction. Free testosterone is checked when the total is near the lower limit of normal, or when a condition such as obesity, diabetes, ageing or HIV alters binding protein levels.
5. Is fatigue a sign of low testosterone?
It can be, but it is one of the least specific signs. Fatigue, low mood and poor concentration overlap with thyroid disorders, anaemia, Vitamin D and B12 deficiency, poor sleep, depression and sleep apnoea. These are usually checked before attributing tiredness to testosterone.
6. Should healthy men get testosterone tested in a routine checkup?
The Endocrine Society recommends against routine screening of men in the general population. Testing is suggested for men with specific conditions such as low libido, erectile dysfunction, infertility or osteoporosis, rather than as a default addition to a wellness panel.
7. What are LH and FSH tests for in a testosterone workup?
They show where the problem originates. High LH and FSH with low testosterone point to primary hypogonadism, where the testes are affected. Low or inappropriately normal LH and FSH point to secondary hypogonadism, originating in the pituitary or hypothalamus, which prompts prolactin and iron studies.
8. Can supplements affect a testosterone test?
Yes. High-dose biotin, common in hair and nail supplements, interferes with several hormone immunoassays. The guideline advises stopping biotin for at least 72 hours before LH and FSH testing. Tell the lab about everything you take, including multivitamins.
9. Does obesity lower testosterone?
Obesity is associated with lower testosterone and also alters sex hormone-binding globulin, which affects how results are interpreted. Untreated sleep apnoea, type 2 diabetes, excess alcohol, chronic opioid use and significant sleep deprivation can all contribute as well, and several of these are reversible.
10. Do I need to fast before a testosterone test?
Yes. The guideline specifies measuring total testosterone in the morning after an overnight fast, because food and glucose intake suppress levels. Plain water is allowed.
11. Can testosterone be tested while I am unwell?
It should not be. Levels fall temporarily during acute illness and with short-term use of drugs such as opioids, so testing during these periods gives a misleadingly low result. Wait until you have recovered, or follow your doctor’s advice on timing.
12. Where can I get a testosterone test done in Pune?
Total testosterone, free testosterone, LH, FSH, prolactin and the supporting tests are available at diagnostic centres across Pune, including Fittr Labs in Kharadi, with home sample collection available. Book an early morning slot, since the sample must be a fasting morning one, and have the result reviewed by a doctor.
