Testosterone blood test: what high and low total and free testosterone mean
Testosterone (total and free) (Testosterone) · Hormone panel (often ordered alone or with LH, FSH and SHBG) · reported in ng/dL for total testosterone (1 ng/dL = 0.0347 nmol/L); pg/mL or ng/dL for free testosterone
Testosterone is the main androgen (male sex hormone), made mostly by the testes in men and in smaller amounts by the ovaries and adrenal glands in women. A testosterone blood test measures the total amount in your blood, and sometimes the small free fraction that is not bound to proteins. In healthy young men the harmonized normal range for total testosterone is about 264 to 916 ng/dL; most labs print something close to 300 to 1,000 ng/dL. In women the range is roughly 15 to 70 ng/dL, about a tenth of the male level.
The two most common reasons for an abnormal result are not disease at all. The first is timing: testosterone peaks between 7 and 10 am and can be 20 to 25 percent lower by late afternoon, and a meal can drop it a further 25 percent for a few hours, so a non-fasting afternoon sample often reads low in a man whose morning level is normal. The second is body weight. Obesity is the single most common cause of a low total testosterone in men, partly because fat tissue converts testosterone to estrogen and partly because it lowers the carrier protein SHBG.
Because of this variability, the Endocrine Society and the American Urological Association both require a low value to be confirmed on a second morning, fasting sample before anything is diagnosed. Around 30 percent of men with one low reading are normal on repeat. A genuinely low level is then sorted into a testicular cause (high LH and FSH) or a pituitary or hypothalamic cause (low or normal LH), and the second group gets a prolactin, iron studies and sometimes a pituitary MRI. In women, a high level matters more than a low one and most often points to polycystic ovary syndrome.
Testosterone at a glance
- What it is: the main androgen hormone; total testosterone counts all of it, free testosterone the 1 to 3 percent that is unbound and active.
- Normal men: about 264–916 ng/dL (9.2–31.8 nmol/L) in healthy non-obese men aged 19 to 39 on CDC-standardised assays; most labs print 300–1,000 ng/dL.
- Normal women: roughly 15–70 ng/dL total; free testosterone about 0.3–1.9 pg/mL depending on the lab. A value above 150–200 ng/dL in a woman needs an urgent look for a tumour.
- Low in men: below 264–300 ng/dL on two separate morning fasting samples, with symptoms, is the Endocrine Society and AUA definition of testosterone deficiency.
- High in men: above about 1,000 ng/dL usually means testosterone or anabolic steroid use; rarely a testicular or adrenal tumour.
- Next step: repeat between 7 and 10 am fasting, add SHBG and free testosterone if borderline or if you are obese, diabetic or older, then LH, FSH and prolactin if confirmed low.
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What Testosterone measures
In men, testosterone is made by the Leydig cells of the testes in response to luteinising hormone (LH) from the pituitary, which in turn answers to GnRH from the hypothalamus. In women about a quarter comes from the ovaries, a quarter from the adrenal glands and half from conversion of weaker androgens (DHEA, androstenedione) in fat and skin. Once in the blood, about 40 to 60 percent is bound tightly to sex hormone-binding globulin (SHBG), most of the rest loosely to albumin, and only 1 to 3 percent floats free. Free plus albumin-bound testosterone together are called bioavailable testosterone.
Total testosterone is measured by immunoassay in most labs, which is accurate in the male range but imprecise below about 100 ng/dL, so for women and children liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the recommended method. Free testosterone is best measured by equilibrium dialysis or calculated from total testosterone, SHBG and albumin (the Vermeulen equation). Direct analogue free testosterone immunoassays are inaccurate and the Endocrine Society advises against them, so check which method your lab used.
Testosterone has a strong daily rhythm, highest in the early morning and 20 to 25 percent lower by 4 pm in young men (the swing flattens with age), and falls for several hours after a glucose load or a meal. It is also lowered by acute illness, fasting beyond 48 hours, intense training blocks and poor sleep, and the total value rises or falls with SHBG even when the free level has not changed. Anything that raises SHBG (ageing, hyperthyroidism, liver disease, oral estrogen, anticonvulsants) raises total testosterone; anything that lowers it (obesity, insulin resistance, hypothyroidism, glucocorticoids, androgens) lowers total testosterone.
Normal range for Testosterone
Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.
| Group | Typical range (ng/dL for total testosterone (1 ng/dL = 0.0347 nmol/L); pg/mL or ng/dL for free testosterone) | Notes |
|---|---|---|
| Men 19–39, harmonized reference range | 264–916 ng/dL (9.2–31.8 nmol/L) | Travison et al. 2017, healthy non-obese men on CDC-standardised assays; adopted by the Endocrine Society. Labs differ; many print 300–1,000 ng/dL. |
| Men, Endocrine Society and AUA threshold for deficiency | Below 264 ng/dL (Endocrine Society) or below 300 ng/dL (AUA) | Only on two separate morning fasting samples, together with consistent symptoms. |
| Men, free testosterone | About 50–210 pg/mL by equilibrium dialysis or calculation; lower limit roughly 64 pg/mL in young men | Method-dependent; useful when total is 200–400 ng/dL or SHBG is abnormal. |
| Men over 65 | Average total about 350–450 ng/dL; roughly 20 percent are below 300 ng/dL | Testosterone falls about 1 to 2 percent a year from the 30s, mostly because of weight gain and illness rather than age alone. |
| Women, premenopausal | About 15–70 ng/dL total (0.5–2.4 nmol/L) | Immunoassays are unreliable here; LC-MS/MS preferred. Peaks mid-cycle. |
| Women, postmenopausal | About 10–40 ng/dL total | Ovarian output continues after menopause but falls; adrenal androgens decline with age. |
| Women, tumour threshold | Above 150–200 ng/dL total (or DHEA-S above 700 mcg/dL) | Prompts imaging of ovaries and adrenals for an androgen-secreting tumour, especially with rapid virilisation. |
| Boys before puberty | Below about 20–30 ng/dL | Rises through puberty from age 10 to 14 to the adult range by about 17 to 19. |
High testosterone
In men, a total testosterone above the upper limit (about 916 to 1,000 ng/dL) is most often the result of testosterone replacement, anabolic steroid use or over-the-counter products that contain androgens; levels of 1,500 to several thousand ng/dL are typical of supraphysiological dosing. The body's own production rarely exceeds the range, so a high value in a man not taking anything is checked for a testosterone-secreting testicular or adrenal tumour, androgen insensitivity (very high testosterone with female or undervirilised features), or a high SHBG from hyperthyroidism or liver disease, in which case the free testosterone is normal and nothing is wrong.
In women, a mildly to moderately raised testosterone (roughly 70 to 150 ng/dL) is the hallmark of polycystic ovary syndrome, which affects 6 to 12 percent of women of reproductive age and is defined by any two of raised androgens, irregular ovulation and polycystic ovaries on ultrasound. Non-classic congenital adrenal hyperplasia (checked with a morning 17-hydroxyprogesterone), Cushing's syndrome and some medications (danazol, testosterone gels, DHEA supplements, some progestins) are the other common causes.
A testosterone above 150 to 200 ng/dL in a woman, or a rise that has happened over months with deepening voice, enlargement of the clitoris, male-pattern balding or loss of breast tissue (virilisation), is treated as a possible ovarian or adrenal tumour until imaging says otherwise. Most such tumours are benign, but they need to be found and removed.
Common causes
Testosterone replacement therapy
Injections produce peaks of 1,000 to 1,500 ng/dL or more a few days after a dose and troughs before the next; gels and patches give steadier levels. The timing of the sample relative to the dose determines the result.
Anabolic steroid or 'prohormone' use
Supraphysiological doses give total testosterone of 2,000 to 5,000 ng/dL or more if the compound is testosterone itself, or a paradoxically low testosterone with suppressed LH if it is a synthetic steroid the assay does not detect. LH and FSH are near zero either way.
Polycystic ovary syndrome (women)
The commonest cause of high testosterone in women; usually 60 to 150 ng/dL with raised free testosterone because insulin resistance lowers SHBG. Comes with irregular periods, acne, excess hair and often weight gain.
Non-classic congenital adrenal hyperplasia (women)
A partial 21-hydroxylase enzyme deficiency affecting about 1 in 100 to 1 in 1,000 people depending on ancestry; mimics PCOS and is identified by a morning 17-hydroxyprogesterone above 200 ng/dL.
Androgen-secreting ovarian or adrenal tumour
Rare but important; testosterone above 150 to 200 ng/dL in a woman, rapid onset over months and virilisation. Adrenal tumours usually also raise DHEA-S above 700 mcg/dL.
High SHBG (hyperthyroidism, liver disease, oral estrogen, anticonvulsants, ageing)
Raises total testosterone without changing the free fraction; the free or bioavailable testosterone is normal and no treatment is needed for the testosterone itself.
Testicular or adrenal tumour (men)
Leydig cell tumours and some adrenal carcinomas secrete testosterone; very rare, usually with a palpable testicular mass or imaging finding.
Androgen insensitivity syndrome
A receptor defect in a genetically male person; testosterone is high or high-normal in the male range but the body cannot respond, so development is female or partly female.
Cushing's syndrome and DHEA supplements (women)
Excess cortisol drives adrenal androgen production; over-the-counter DHEA converts to testosterone and can double a woman's level.
Sample timing, stress and exercise
A morning sample after a night's sleep is at the daily peak; heavy resistance exercise raises testosterone 15 to 30 percent for an hour. Neither produces a truly abnormal value in an untreated man.
Symptoms that can go with it
- Often none in men on replacement; with abuse, acne, oily skin, aggression, mood swings and shrinking testicles
- Breast enlargement (gynecomastia) in men, from conversion of excess testosterone to estrogen
- Thickened blood (high hematocrit), headaches, high blood pressure and sleep apnea worsening in men on high doses
- Infertility and low sperm count in men, because external testosterone switches off LH and FSH
- Irregular or absent periods, acne and excess facial or body hair in women (PCOS pattern)
- Deepening voice, male-pattern hair loss, clitoral enlargement or loss of breast tissue in women, which suggests a tumour and needs prompt assessment
- Weight gain around the middle, dark velvety skin patches and difficulty conceiving in women with insulin resistance
Low testosterone
In men, a low testosterone means the testes are not making enough, either because they are failing (primary hypogonadism, with high LH and FSH) or because the pituitary and hypothalamus are not driving them (secondary hypogonadism, with low or inappropriately normal LH). Classic primary causes are Klinefelter syndrome, testicular injury, chemotherapy, mumps orchitis and radiation. Secondary causes are far more common and include obesity, type 2 diabetes, opioid and glucocorticoid use, obstructive sleep apnea, pituitary tumours including prolactinoma, hemochromatosis, anabolic steroid withdrawal and any serious acute or chronic illness.
The number alone does not make the diagnosis. Guidelines require a total testosterone below 264 to 300 ng/dL on at least two morning fasting samples plus symptoms such as low libido, erectile dysfunction, loss of morning erections, fatigue, loss of muscle, breast tenderness or low bone density. A value of 200 to 350 ng/dL with borderline symptoms is where free testosterone and SHBG help: a man with obesity and a low SHBG may have a total of 250 ng/dL but a normal free level, and does not have hypogonadism. A total below 150 ng/dL, or any low value with headache, visual change or high prolactin, warrants a pituitary MRI.
In women there is no agreed threshold for 'low testosterone'. Levels fall naturally with age and after removal of the ovaries, and low values are seen with oral contraceptives, oral estrogen, adrenal insufficiency, hypopituitarism and anorexia. The Endocrine Society recommends against diagnosing an androgen deficiency syndrome in women because symptoms do not track with levels; the one evidence-based use is a short trial of transdermal testosterone for low desire in postmenopausal women, which is monitored to keep levels within the female range.
Common causes
Obesity and insulin resistance
The leading cause in men under 65. Fat tissue converts testosterone to estradiol, which suppresses LH, and insulin resistance lowers SHBG; men with a BMI over 35 have on average 25 to 40 percent lower total testosterone, and the level rises as weight falls.
Afternoon, non-fasting or ill-timed sample
Testosterone is 20 to 25 percent lower in the late afternoon than at 8 am and falls a further 25 percent for 2 to 3 hours after a glucose-containing meal; a repeat morning fasting sample is normal in about 30 percent of men with one low result.
Opioids, glucocorticoids and some other drugs
Long-term opioids suppress GnRH and lower testosterone in up to two-thirds of men taking them; prednisone, anabolic steroids (after stopping), ketoconazole, spironolactone, cimetidine and statins in a small way also lower it.
Type 2 diabetes and metabolic syndrome
About a third of men with type 2 diabetes have a total testosterone below 300 ng/dL, mostly secondary (low LH) and tied to visceral fat and insulin resistance rather than to the diabetes itself.
Obstructive sleep apnea and sleep deprivation
Fragmented sleep blunts the night-time LH pulses that drive the morning peak; one week of 5 hours' sleep a night lowered daytime testosterone 10 to 15 percent in healthy young men, and untreated sleep apnea is a frequent finding in men with low levels.
Ageing
Total testosterone falls about 1 percent a year and free testosterone about 2 percent a year from the 30s, but healthy lean men often stay in range into their 80s; most of the age effect is weight gain, medication and illness.
Pituitary and hypothalamic disease
Prolactinoma (prolactin usually above 100 ng/mL), non-functioning pituitary adenomas, hemochromatosis (iron deposition in the pituitary), head injury, radiation and Kallmann syndrome all lower LH and therefore testosterone.
Primary testicular failure
Klinefelter syndrome (XXY, about 1 in 600 men, often undiagnosed), undescended testes, mumps orchitis, testicular torsion or trauma, chemotherapy and pelvic radiation; LH and FSH are high because the pituitary is trying to compensate.
Acute or chronic illness
Any significant illness, surgery, intensive care stay, HIV, cirrhosis, chronic kidney disease, heart failure and COPD lower testosterone, which is why guidelines say not to test during or soon after an illness.
Alcohol excess, heavy endurance training and under-eating
Chronic heavy drinking damages Leydig cells and the pituitary; prolonged energy deficit (very low body fat, overtraining, eating disorders) switches off GnRH in both men and women.
Symptoms that can go with it
- Low sex drive, fewer or weaker erections and loss of spontaneous morning erections in men
- Persistent fatigue, low mood, irritability and poor concentration
- Loss of muscle mass and strength, with more body fat, especially around the abdomen
- Breast enlargement or tenderness, reduced facial and body hair, small or softening testicles
- Hot flushes and sweats when the drop is abrupt (after orchiectomy or stopping anabolic steroids)
- Low bone density or fractures from minor falls
- Infertility and a low sperm count
- In women: low desire, low energy and reduced bone density after ovary removal, though symptoms correlate poorly with the number
Read it alongside
- SHBG — tells you whether a low or high total testosterone is real or just a protein effect; needed to calculate free testosterone and almost always abnormal in obesity, thyroid disease and liver disease.
- Free testosterone (calculated or by equilibrium dialysis) — the active fraction; decides borderline cases with a total of 200 to 400 ng/dL.
- LH and FSH — high with low testosterone means the testes are failing (primary); low or normal means the problem is in the pituitary or hypothalamus (secondary), or that the sample was taken during illness.
- Prolactin — a high level suppresses LH and is the most treatable pituitary cause of low testosterone; measured in every man with confirmed secondary hypogonadism.
- Estradiol — raised in obesity and with testosterone therapy; the testosterone-to-estradiol balance explains gynecomastia and some fertility problems.
- DHEA-S and 17-hydroxyprogesterone — in women with high testosterone, separate adrenal causes (tumour, congenital adrenal hyperplasia) from ovarian ones (PCOS).
- Hemoglobin and hematocrit — testosterone stimulates red cell production; a hematocrit above 54 percent on treatment is the usual reason to pause or lower a dose.
- Glucose, A1C and triglycerides — low testosterone in men clusters with insulin resistance and metabolic syndrome; improving these often raises testosterone, and ferritin is checked once to exclude hemochromatosis.
What usually happens next
- A single low result is repeated on a separate day, between 7 and 10 am, fasting, when you are well and not sleep-deprived; two low values with symptoms are needed before any diagnosis.
- If the total is borderline (200 to 400 ng/dL) or you are obese, have diabetes, are over 60 or take drugs that alter SHBG, ask for SHBG and a calculated or equilibrium-dialysis free testosterone.
- Confirmed low testosterone is followed by LH, FSH and prolactin, and often iron studies, a CBC, a PSA in men over 40, and a bone density scan if the level is very low or longstanding.
- A total below 150 ng/dL, a raised prolactin, headaches, visual symptoms or other pituitary hormone deficits lead to a pituitary MRI; a very small testicular volume prompts a karyotype for Klinefelter syndrome.
- In women with high testosterone, expect a DHEA-S, 17-hydroxyprogesterone, pelvic ultrasound and a check for Cushing's; a level above 150 to 200 ng/dL or rapid virilisation leads to prompt imaging of ovaries and adrenals.
- Ask whether reversible contributors (weight, sleep apnea, opioids, alcohol, overtraining) have been addressed before discussing replacement, and if replacement is started, expect hematocrit, PSA and testosterone levels to be rechecked at 3 to 6 months and then yearly.
Diet, lifestyle and natural levers with evidence
What can move Testosterone once the cause is known. Nothing here replaces finding the cause.
Weight loss in men with obesity
Strong evidenceA meta-analysis of 24 studies found that low-calorie diets raised total testosterone by an average of about 84 ng/dL (2.9 nmol/L) and bariatric surgery by about 250 ng/dL (8.7 nmol/L), with the gain proportional to the weight lost; in the EMAS cohort, men who lost 15 percent or more of body weight saw testosterone rise enough to leave the hypogonadal range in most cases. This is the most effective non-drug lever and often removes the need for replacement.
Sleep: 7 to 8 hours and treating sleep apnea
Moderate evidenceIn a controlled study, restricting healthy young men to 5 hours of sleep for one week lowered daytime testosterone by 10 to 15 percent, roughly the decline expected from 10 to 15 years of ageing. Most testosterone is secreted during sleep, so chronic short sleep and untreated obstructive sleep apnea both lower morning levels; CPAP trials show small, inconsistent rises, with the clearest benefit when weight also falls.
Resistance training and regular exercise
Moderate evidenceHeavy compound lifting raises testosterone acutely by 15 to 30 percent for about an hour, and training programmes of 12 weeks or more in sedentary or overweight men produce modest resting increases (typically 5 to 15 percent), largely through fat loss and better insulin sensitivity. Very high-volume endurance training and energy deficit do the opposite, lowering testosterone by 20 to 40 percent in some runners and cyclists.
Do not test within 24 hours of an unusually hard session; the acute changes distort the result in both directions.
Limit alcohol
Moderate evidenceAlcohol is directly toxic to Leydig cells and suppresses LH; men with alcohol use disorder have testosterone levels 20 to 50 percent lower than controls, and levels recover partly within weeks of abstinence. Moderate drinking (1 to 2 drinks a day) has little measurable effect in most studies, so the lever matters mainly for heavier drinkers.
Vitamin D (if deficient)
Preliminary evidenceA one-year trial in 54 overweight men with low vitamin D found 3,332 IU a day raised total testosterone by about 3 nmol/L (86 ng/dL) versus no change on placebo, but larger later trials in men with normal or mildly low vitamin D (including a 12-week trial of 20,000 IU weekly in 100 men) found no effect. Correcting a true deficiency is reasonable; supplementing a normal level does not raise testosterone.
Doses above 4,000 IU a day long term can raise calcium; check a level before taking high doses.
Ashwagandha
Preliminary evidenceIn a 16-week trial of 57 overweight men aged 40 to 70, 600 mg a day of a root extract raised total testosterone by about 15 percent (roughly 45 ng/dL) compared with placebo, and an 8-week trial in 57 young men doing resistance training reported a rise of about 96 ng/dL versus 18 ng/dL on placebo. Trials are small, short and mostly industry-funded, and the effect is modest; it does not move a man from clearly hypogonadal to normal.
Reports of liver injury with some extracts; can raise thyroid hormone levels; avoid in pregnancy and with sedatives or immunosuppressants.
When to see a clinician promptly
- A testosterone above 150 to 200 ng/dL in a woman, or any rapid deepening of the voice, clitoral enlargement or male-pattern balding: possible androgen-secreting tumour, needs prompt imaging.
- Low testosterone with headaches, loss of peripheral vision, a raised prolactin or other hormone deficits: possible pituitary tumour.
- A testicular lump, swelling or pain alongside an abnormal testosterone: needs examination and ultrasound within days.
- Low testosterone with symptoms (low libido, erectile dysfunction, fatigue, low mood) confirmed on two morning samples, to discuss causes and whether treatment is appropriate.
- On testosterone treatment or anabolic steroids: a hematocrit above 54 percent, chest pain, calf swelling, sudden breathlessness or severe headache, which can indicate a clot or stroke.
- A boy with no signs of puberty by 14, or a girl with signs of virilisation at any age.
Frequently asked questions
What is a normal testosterone level by age?
The harmonized reference range for healthy non-obese men aged 19 to 39 is 264 to 916 ng/dL. Average levels then fall about 1 percent a year, so a typical 40-year-old has around 550 ng/dL, a 60-year-old around 450 and a 75-year-old around 400, but healthy lean men often stay above 500 at any age. There is no separate 'normal for age' cut-off in the guidelines; the same lower limit of 264 to 300 ng/dL applies to all adult men, because low levels in older men are usually caused by weight, illness or medication rather than age itself.
Is a testosterone of 300 low?
It is borderline. A total of 300 ng/dL sits at the lower limit used by the American Urological Association and just above the Endocrine Society's 264 ng/dL. On its own it is not a diagnosis: the test should be repeated between 7 and 10 am fasting, and if it is still around 300, SHBG and free testosterone decide whether it is genuinely low. A man with symptoms, two values under 300 and a low free testosterone meets the definition of testosterone deficiency; a man who feels well with a normal free level does not.
What time of day should testosterone be tested?
Between 7 and 10 am, fasting, on a day you are well and have slept normally. Testosterone peaks in the early morning and can be 20 to 25 percent lower by late afternoon in younger men, and a meal with carbohydrate lowers it by around 25 percent for two to three hours. Guidelines require two morning samples before diagnosing low testosterone because one reading is wrong in about a third of men.
What is the difference between total and free testosterone?
Total testosterone counts every molecule in the blood, including the 98 percent that is bound to SHBG and albumin. Free testosterone is the 1 to 3 percent that is unbound and able to enter cells. Total is the standard first test; free is added when the total is borderline or when SHBG is likely to be abnormal (obesity, diabetes, thyroid disease, liver disease, older age, some medications). Ask for a calculated or equilibrium-dialysis free testosterone, not the direct analogue immunoassay, which is inaccurate.
What causes high testosterone in women?
Polycystic ovary syndrome is by far the most common cause and usually gives levels of 60 to 150 ng/dL with irregular periods, acne or excess hair. Other causes are non-classic congenital adrenal hyperplasia, Cushing's syndrome, testosterone or DHEA products, and rarely an ovarian or adrenal tumour. A level above 150 to 200 ng/dL, or symptoms such as a deepening voice that have appeared over months, point toward a tumour and need imaging.
Can low testosterone be reversed naturally?
Often, when the cause is weight, sleep, alcohol or medication. Losing 10 to 15 percent of body weight raises testosterone by roughly 100 to 250 ng/dL in men with obesity, treating sleep apnea and sleeping 7 to 8 hours restores the night-time surge, and cutting heavy drinking lets Leydig cell function recover. Supplements such as ashwagandha, zinc or vitamin D produce small gains, mostly in men who were deficient. Testicular failure, pituitary disease and genetic causes do not reverse with lifestyle and need medical treatment.
Does testosterone need to be checked before starting treatment, and how often after?
Yes: two low morning values plus symptoms are required, along with LH, FSH, prolactin, a hematocrit and, in men over 40, a PSA. Once treatment starts, testosterone, hematocrit and PSA are rechecked at about 3 and 6 months and then yearly, aiming for a mid-normal level (roughly 400 to 700 ng/dL). Men who want children should know that external testosterone suppresses sperm production and alternatives exist.
Do I need to fast for a testosterone test?
Guidelines recommend it. A glucose load lowers testosterone by about 25 percent for up to two to three hours in both men with and without low levels, so a sample taken after breakfast can read falsely low. Water is fine. The sample should also be taken in the morning and not during or within a few weeks of an acute illness.
References
- Testosterone levels test. MedlinePlus, US National Library of Medicine (2023)View source
- Bhasin S, Brito JP, Cunningham GR, et al.. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism (2018)View source
- Travison TG, Vesper HW, Orwoll E, et al.. Harmonized reference ranges for circulating testosterone levels in men of four cohort studies in the United States and Europe. Journal of Clinical Endocrinology and Metabolism (2017)View source
- Mulhall JP, Trost LW, Brannigan RE, et al.. Evaluation and management of testosterone deficiency: AUA guideline. Journal of Urology (2018)
- Leproult R, Van Cauter E. Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA (2011)View source
- Corona G, Rastrelli G, Monami M, et al.. Body weight loss reverts obesity-associated hypogonadotropic hypogonadism: a systematic review and meta-analysis. European Journal of Endocrinology (2013)
- Caronia LM, Dwyer AA, Hayden D, et al.. Glucose ingestion acutely lowers circulating testosterone levels in men. Clinical Endocrinology (2013)
- Wierman ME, Arlt W, Basson R, et al.. Androgen therapy in women: a reappraisal: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism (2014)
- Pilz S, Frisch S, Koertke H, et al.. Effect of vitamin D supplementation on testosterone levels in men. Hormone and Metabolic Research (2011)
- Lopresti AL, Drummond PD, Smith SJ. A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha (Withania somnifera) in aging, overweight males. American Journal of Men's Health (2019)
- Male hypogonadism. Merck Manual Professional Version (2024)
- Male hypogonadism. Mayo Clinic (2023)View source
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