What is low testosterone?
Testosterone is the hormone that steers muscles, bone, brain, skin, prostate and sexual organs. It is made in the testicles, on the orders of the pituitary through LH and FSH. Of the testosterone in your blood only 2% is free; about 60% is firmly bound to SHBG and 38% loosely to albumin. Only the free and the albumin-bound part works, and that is why SHBG has a say in how much of a total value remains. From 35 years testosterone falls slowly in healthy men; a man of 75 still has about 70% of the value of a 25-year-old. That fall is ordinary, and the link with complaints is unclear in healthy older men. What lowers it harder than the years is the belly: in a cohort waist circumference had more influence on testosterone than age, and men with diabetes have on average 2.66 nmol/L less. Lack of sleep, heavy stress, alcohol and medicines such as opiates and prednisone lower it too, and it recovers once the cause is gone. The value has a daily rhythm, with its peak in the morning, and fluctuates from day to day. That is why testosterone is drawn before ten in the morning, and with a value below 11 nmol/L once more after a few weeks; the average of the two counts. A true deficiency, in which the testicles or the pituitary make too little, is rare and can be recognised from LH and FSH.
Which blood values show low testosterone?
Every value below has its own page with the reference ranges of four Dutch labs.
| Value | What it shows | Points here when |
|---|---|---|
| Total testosteronedefining | The number the NHG steers on: an average below 11 nmol/L, measured twice before ten in the morning. | low |
| SHBG | Binds 60% of testosterone. Rises with age and falls with excess weight, and so decides how much of the total works. | abnormal |
| Free testosterone | The working share, calculated from total, SHBG and albumin. Reads a normal total with a high SHBG as low after all. | low |
| FAI (free androgen index) | Total divided by SHBG: the same question in one ratio. | low |
| LH | The pituitary's order. High with a low testosterone points to the testes, low to the pituitary itself. | abnormal |
| FSH | The second pituitary hormone, pointing in the same direction. | abnormal |
| Prolactin | A high prolactin can suppress testosterone production; a prolactinoma is one of the central causes the NHG wants excluded. | high |
| Oestradiol | Made from testosterone, mostly in fat tissue. Says something about the balance, not about the deficiency itself. | abnormal |
What are the symptoms of low testosterone?
These complaints are described for low testosterone in guidelines and research. None of them is exclusive to it: the same complaints fit many other explanations, and an abnormal value can exist without any of them.
A falling testosterone you do not feel as a number. From 35 years it falls gradually in healthy men, and that fall is ordinary; in older men without clear indications measuring therefore makes little sense. The complaints above are each of them very common without a deficiency too, and that is precisely why the diagnosis asks for complaints and a twice-measured low testosterone.
- Less desire for sex and less arousalin the guideline
For the NHG the complaint that must be in the foreground before a test is worthwhile.
- Erection problemsin the guideline
Usually without a deficiency: for erection problems on their own the NHG finds routine testing pointless. Morning erections that are intact point to a psychological cause sooner.
- Extreme tiredness and a lack of energy and motivationin the guideline
Also described at iron deficiency, anaemia, underactive thyroid, vitamin B12 deficiency.
- Mood changesin the guideline
Also described at underactive thyroid, vitamin B12 deficiency.
- Irritabilityin the guideline
- Memory problemsin the guideline
Also described at iron deficiency, underactive thyroid, vitamin B12 deficiency.
- Muscle weakness and less muscle massin the guideline
On physical examination the GP also looks for little body hair, small testes and more belly fat.
Also described at underactive thyroid, vitamin D deficiency.
A complaint points in more than one direction, and a measurement explains no complaint: blood testing shows where your values stand, the reading and the diagnosis belong with your GP. The complaint list follows the Dutch GP guideline on sexual complaints (NHG).
What causes low testosterone?
Weight and health
Belly fat and chronic illness push testosterone down harder than the calendar does.
- Excess weight, belly fat above all: in one cohort waist circumference had more influence than age
- Diabetes, in which testosterone is on average 2.66 nmol/L lower
- Chronic illnesses such as HIV, COPD or cancer, and poor general health
Medication
Some medicines lower the level, and that is one of the first things the GP checks.
- Opiates
- Corticosteroids such as prednisone
- Anti-epileptics
Pituitary or testes
Rarer, but the reason the NHG refers at an average below 11 nmol/L: central causes have to be excluded.
- A pituitary tumour such as a prolactinoma, or a pituitary that makes too little
- Klinefelter syndrome or another chromosomal condition
What is low testosterone confused with?
Each with the one value that tells the two apart.
Erection problems without a deficiency
By far most erection problems have a vascular or psychological cause. The NHG only has testosterone measured when less desire is in the foreground and there are other indications; otherwise a normal testosterone says nothing new.
Distinguishing value: Total testosterone
Prolactinoma
A benign pituitary growth that makes prolactin and so suppresses testosterone. Prolactin points that way, and it is the central cause the urologist rules out.
Distinguishing value: Prolactin
Underactive thyroid
Also tired, low and less desire, through a different hormone. TSH keeps the two apart.
Distinguishing value: TSH
Type 2 diabetes
Erection problems are a late sign of diabetes, and men with diabetes have a lower testosterone on average. Whether that is cause or effect is not known; fasting glucose says whether sugar is part of it.
Distinguishing value: Fasting glucose
What you do about low testosterone
Start with what lowers testosterone, because that is almost always reversible. Belly fat is the largest factor: fat tissue converts testosterone into oestrogen and lowers SHBG, and losing weight lifts the value measurably, often more than what was lost with age. Sleep seven to eight hours, because most testosterone is made in deep sleep and a week of short nights already lowers the morning value sharply. Do strength training, two to three times a week, and exercise daily, because working muscles ask for the hormone. Drink little alcohol, because that inhibits production and speeds up the conversion to oestrogen. Keep your diabetes well controlled, and look at your medicines: opiates, prednisone and some medicines against hair loss or an enlarged prostate lower testosterone, and anabolic steroids or testosterone from outside shut down the body's own production. Testosterone replacement only comes into view with complaints and a twice-measured low average, after a look at LH, FSH, prolactin, haemoglobin and prostate, and it is then a choice with pros and cons that you make with a doctor; it is not a remedy for tiredness or a dip. Measure before ten in the morning, rested and not after a hard training session or an evening of drinking, and repeat a low value after a few weeks. Measure again after three to six months if you have lost weight or sleep better: that is the term over which the value shows the change.
From which total testosterone does a lab call it low?
This is what the four largest Dutch labs publish themselves, side by side.
0.3 – 1.7nmol/L
Between 0 and 0.3 and between 1.7 and 2.6 it depends on the lab, because each sets its limits on its own method and population. Above 2.6 every lab calls it abnormal.
every lab calls 0.3 – 1.7 nmol/L normal. Between 0 and 0.3 and between 1.7 and 2.6 it depends on the lab.
Every age group per lab
| Lab | Group | Reference range |
|---|---|---|
| Unilabs(Saltro, Medlon, SHO, Atalmedial)2026 | Men 20 to 50 yrs | 9.0–37.3 nmol/L |
| Men 50 to 80 yrs | 7.6–37.1 nmol/L | |
| Men from 80 yrs | 5.4–36.8 nmol/L | |
| Women 20 to 50 yrs | 0.2–2.1 nmol/L | |
| Women from 50 yrs | 0.1–1.8 nmol/L | |
| Star-shl2026 | Men 18 to 49 yrs | 8.6–29.0 nmol/L |
| Men from 50 yrs | 6.7–25.7 nmol/L | |
| Women 18 to 49 yrs | 0.3–1.7 nmol/L | |
| Women from 50 yrs | 0.1–1.4 nmol/L | |
| Certe2026 | Women 16 to 20 yrs | 0.1–1.7 nmol/L |
| Men 16 to 20 yrs | 4–24 nmol/L | |
| Women (all ages) | 0.17–1.81 nmol/L | |
| Men (all ages) | 8.8–32.4 nmol/L | |
| Clinical Diagnostics2026 | Men | 6.1–27.3 nmol/L |
| Women | 0–2.6 nmol/L |
How to get low testosterone measured
- Fasting
- No fasting, but early: the NHG has testosterone measured before ten in the morning, because the daily rhythm makes the value come out lower later in the day. With a result below 11 nmol/L you repeat the measurement after a few weeks and the average counts.
- Material
- Venous blood, drawn at one of our collection points.
- Results
- Results within 24 hours of analysis, in the app.
- Referral
- No referral from a GP required.
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What are the symptoms of a testosterone deficiency?
Less desire for sex and less arousal, erectile problems, marked tiredness, irritability, a poorer memory, mood changes and muscle weakness, and on examination small testicles, little body hair, little muscle mass and more belly fat. Each of those complaints is also common without a deficiency, with lack of sleep, stress and excess weight first of all, and that is why the diagnosis asks for complaints and a twice-measured low testosterone.
What is a normal testosterone value in men?
Between 12 and 40 nmol/L, drawn before ten in the morning. The bands on the reports start lower: for a man of 20 to 50 years one report still calls 9.0 normal, others 8.6, 8.8 and even 6.1, because those bands describe what is usual and not what is healthy. An average below 11 nmol/L, measured twice, is with complaints a deficiency that calls for follow-up. So a value of 9.5 is normal on paper and low for anyone with complaints alongside.
Why must testosterone be measured in the morning?
Because it has a daily rhythm with the highest value in the morning: later in the day the result comes out lower without anything having changed. So have blood drawn before ten in the morning, rested and not after a hard training session or an evening of drinking. The level also fluctuates from day to day, and that is why you repeat a value below 11 nmol/L after a few weeks and the average of the two counts.
Does testosterone fall with age?
Yes, in healthy men from about 35 years, gradually: a man of 75 still has about 70% of the value of a 25-year-old. That fall is ordinary, and the link with sexual complaints is unclear in healthy older men. In a cohort waist circumference weighed more than age, and in very healthy men above 40 no link with age was found at all; what you lose with the years, you lose mainly to the belly and to sleep.
What does a low testosterone mean with excess weight or diabetes?
That the deficiency usually does not stand on its own, and is usually reversible. Men with diabetes have on average 2.66 nmol/L less testosterone, and belly fat converts testosterone into oestrogen and lowers SHBG. Whether the low testosterone is cause or consequence, nobody knows for certain, but losing weight and better-controlled diabetes lift the value. That is why weight, sleep and medicines come first, and replacement only comes into view with complaints and a twice-measured low average.
Sources
- 1.NHG-Standaard Seksuele klachten. 2023. richtlijnen.nhg.org
- 2.Bhasin S et al., Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline, Journal of Clinical Endocrinology & Metabolism. 2018. doi.org
- 3.European Association of Urology, Guidelines on sexual and reproductive health. 2025. uroweb.org
This page explains what a result means. It is not a diagnosis and not treatment advice. Discuss complaints or an abnormal value with your doctor.
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