This page is educational and is not medical advice. Desire is biological, psychological and relational at the same time, so a single lab value is one input rather than an answer on its own.
Most low desire comes from accumulated everyday load rather than from a disease, and the usual drivers are sleep debt, chronic stress, hard training without recovery, under-eating, alcohol, low mood and common medications. Expert reviews of low sexual desire describe it as multifactorial, with biological, psychological, relational and contextual contributors that interact rather than compete[1]. That matters, because it explains why two people with almost identical bloodwork can report very different desire.
Several everyday causes tend to stack up. The most common ones are worth naming plainly.
Medications deserve their own mention, because they are the single easiest cause to overlook. Reviews of sexual desire and pharmacologic management describe reduced desire as a recognised effect of several widely used drug classes, including some antidepressants, antipsychotics, opioids and hormonal agents[3]. Even statins have been examined for a possible link, with pharmacovigilance analysis suggesting a possible association with decreased libido rather than a settled one[4]. Hormonal contraception raises sex hormone binding globulin in many people, which lowers the free fraction of testosterone.
None of this is a diagnosis. It is a list of things worth reviewing honestly before anyone orders a tube of blood.
Six markers do most of the useful work for low desire, and they are total testosterone, free testosterone, SHBG, prolactin, estradiol and TSH. Together they describe how much androgen you make, how much of it is biologically available, whether the pituitary signal is being interfered with, and whether thyroid function is dragging on energy and mood.
| Marker | Why it is linked to low desire | What a result can and cannot tell you |
|---|---|---|
| Total testosterone | Androgens support sexual motivation in both men and women | Shows total circulating androgen on that morning. Cannot show how much is biologically active, and moves with sleep, illness and energy intake |
| Free testosterone | The unbound fraction that can act on tissue | Often tracks symptoms better than total. Values depend heavily on the assay or calculation used, so method matters |
| SHBG | High SHBG binds testosterone and lowers the free fraction | Explains why free and total testosterone can disagree. Does not itself cause symptoms, it reframes the testosterone result |
| Prolactin | Raised prolactin suppresses the pituitary signal to the gonads and is associated with reduced desire | A single raised value is common and often non-specific. Needs a rested repeat draw and clinical context before it means anything |
| Estradiol | Estrogen balance shapes genital tissue health, mood and desire in women, and in men estradiol comes from aromatised testosterone | Must be read with cycle phase, life stage and sex. In men it needs a sensitive assay to be meaningful |
| TSH | Thyroid disorders are associated with fatigue, low mood and sexual dysfunction | A screening signal for thyroid function. Does not localise the cause, and shifts with time of day, illness and some supplements |
Typical lab reference ranges give context for those numbers. The ranges below are the kind most laboratories report for adults.
| Marker | Standard range |
|---|---|
| Total testosterone, men | 264 to 1200 ng/dL |
| Total testosterone, women | 8 to 120 ng/dL |
| SHBG | roughly 10 to 80 nmol/L, with higher values usual in women |
| Prolactin | 2 to 25 ng/mL in men and 2 to 30 ng/mL in non-pregnant women |
| Estradiol, men | roughly 10 to 40 pg/mL |
| TSH | 0.45 to 4.5 mIU/L |
Reference ranges vary by lab, assay, age and sex, and in women they vary by cycle phase as well. Always read your result against the range printed on your own report, and discuss it with a clinician who has your history in front of them.
Total testosterone is the single most informative starting marker for low desire, but on its own it explains fewer cases than most people expect. Androgens act on brain circuits involved in sexual motivation in both sexes, and a long-standing review of the field describes testosterone as influencing libido and general wellbeing in women as well as men[5]. Research in postmenopausal women with persistent low desire suggests that testosterone therapy is associated with modest improvements in desire compared with placebo[6], and more recent reviews reach broadly similar conclusions for perimenopausal and postmenopausal women[7]. Any such therapy is a decision a licensed provider makes after evaluating whether it is appropriate for the individual.
What else moves this marker matters just as much. Testosterone follows a daily rhythm and is highest in the morning, so a late-afternoon draw can read low in someone with perfectly normal production. Body composition shifts it too. Because of that variability, a single low value is one observation rather than a conclusion, and a repeat fasting morning draw is the standard next step. You can read more about what the marker measures on the Testosterone Total page.
Free testosterone is the fraction not bound to carrier proteins, which makes it the portion able to act on tissue, and it often tracks symptoms better than the total value. Most circulating testosterone is bound tightly to sex hormone binding globulin and loosely to albumin. When binding protein levels shift, total testosterone can sit comfortably mid-range while the active fraction sits low.
The clinical guideline on systemic testosterone for low desire in women stresses that assay quality and the method used to derive free testosterone materially affect interpretation[8]. Equilibrium dialysis is the reference method, while most panels report a value calculated from total testosterone, SHBG and albumin. Those methods do not always agree, so the same blood can produce different numbers in different labs.
Free testosterone is also pulled around by anything that changes binding proteins, including thyroid status, estrogen exposure, insulin resistance, liver function, age and low energy availability. That is why it is read next to the total value and SHBG rather than alone. The Testosterone Free page covers the measurement detail.
Yes, high SHBG lowers the free testosterone available to tissue, which is one possible reason for low desire in someone whose total testosterone looks normal. SHBG is the transport protein made by the liver that binds testosterone and estradiol. The more of it there is, the smaller the unbound fraction becomes, which is why clinical reviews of androgen therapy in women emphasise reading SHBG alongside testosterone rather than after it[9].
SHBG rises with age, with thyroid overactivity, with estrogen exposure including some hormonal contraceptives, with liver disease and with sustained low energy availability. It falls with insulin resistance, higher body fat, thyroid underactivity and androgen exposure. So a high SHBG result is rarely the end of the trail. It is a prompt to ask what is driving it, and whether the free testosterone number is the one that matches how you actually feel. The SHBG page explains the protein and what shifts it.
Raised prolactin is one of the clearest hormonal contributors to low desire, and it works through two routes at once. Sustained high prolactin suppresses the pulsed signal from the hypothalamus to the pituitary, which lowers luteinising hormone and in turn lowers testosterone production. Separately, prolactin itself is associated with reduced sexual interest. Clinical reviews of low desire describe screening for endocrine contributors such as raised prolactin and thyroid disease as part of a standard workup[10].
The caution is that prolactin is a twitchy marker. Underactive thyroid can raise it too. Laboratory artefacts matter as well, since macroprolactin can inflate a result without causing symptoms. A single mildly raised value is usually repeated under rested conditions. A markedly raised value, or one accompanied by headaches, visual changes or milk production, is worth discussing with a clinician promptly. The Prolactin page covers the marker in more depth.
Estradiol affects desire in both sexes, though the mechanism differs. In women, falling estradiol across the menopause transition is associated with vaginal dryness and discomfort during sex, which can reduce desire indirectly through anticipated pain as well as through direct effects on mood and arousal. Assessment frameworks for low desire in women treat genitourinary symptoms as a core part of the evaluation rather than a side issue[2].
In men, estradiol is produced largely by aromatisation of testosterone in fat and other tissue, and it has a genuine physiological role in libido and bone health. Both unusually low and unusually high values can come with sexual symptoms, which is why the result is interpreted next to testosterone rather than in isolation. Measurement is a practical issue here. Standard immunoassays perform poorly at the low concentrations typical in men, so a sensitive method gives a more trustworthy number.
Estradiol also moves with cycle phase in premenopausal women, with body composition, with alcohol intake, with liver function and with any exogenous hormone exposure. The Estradiol page sets out what the marker reflects.
Yes, thyroid disorders in either direction are associated with reduced sexual desire, and TSH is the usual first-line screen. An underactive thyroid is associated with fatigue, low mood, cold intolerance and slowed metabolism, all of which erode sexual interest before any direct hormonal effect is considered. Thyroid status also changes SHBG and can raise prolactin, so a thyroid abnormality can show up as a confusing testosterone picture. Reviews of low desire include thyroid assessment among the medical contributors worth excluding early[10].
An overactive thyroid is associated with its own cluster of anxiety, poor sleep and weight loss, which can be just as disruptive to desire. TSH itself varies with time of day, with acute illness, with pregnancy and with certain medications, and high-dose biotin supplements can interfere with several thyroid assays and distort the result. That is why a single out-of-range TSH is usually repeated with free thyroid hormones before anyone draws conclusions. The TSH page explains how the marker behaves.
A completely normal hormone panel does not mean nothing is wrong, and in low desire that happens often. Blood tests do not measure relationship satisfaction, sexual boredom, body image, anxiety about performance, past trauma, grief or the simple absence of time and privacy. They do not measure how safe or wanted someone feels. Expert consensus work on low sexual desire places these factors alongside biology rather than below it[1].
Some medical contributors also sit outside a hormone panel. Chronic pain, sleep apnoea, depression, medication effects and pelvic floor problems all affect desire while leaving testosterone, prolactin and TSH unremarkable. A panel also captures one morning. It cannot describe a pattern across weeks.
When desire stays low with a normal panel, the conversation shifts toward psychological, relational and pharmacological approaches. Drug options for low desire that is not explained by laboratory findings exist and remain genuinely debated in the literature, with commentary questioning the strength of the regulatory evidence base[11], and a systematic review of options for female desire, arousal and orgasmic difficulties reported effects that vary considerably by intervention[12]. Whether any of these is appropriate is a decision for a licensed provider, not a self-assessment.
Some patterns around low desire deserve prompt medical attention rather than watchful waiting. Book an appointment soon, and describe the full picture rather than the sex-drive part alone, in any of these situations.
If you are having thoughts of self-harm, call or text 988 (US) or your local emergency number now.
None of these symptoms confirms a condition by itself. They are reasons to be seen rather than conclusions, and self-diagnosis from a symptom list is the one approach that reliably wastes time.
All six markers discussed here are measured together in a single blood draw. The Hormone Panel for Him covers total testosterone, free testosterone, SHBG, prolactin, estradiol and TSH, which is the combination that lets a clinician read the androgen picture, the binding protein that shapes it, the pituitary signal and thyroid function at the same time rather than in separate appointments.
FitScript builds its membership around repeat testing rather than one-off snapshots, with 150+ biomarkers tested per year, and Atlas, FitScript's AI health advisor, explains what each result means in plain language and how it has changed since the last draw. Any decision about therapy, including hormone therapy of any kind, is made by a licensed clinician who reviews the full picture and evaluates whether it is appropriate for you.
Bring your results to that conversation along with your sleep, training, alcohol intake and medication list, because the panel answers only part of the question.
Low libido means a persistent reduction in sexual desire that bothers you or your partner. It is defined by the change from your own baseline rather than by comparison with anyone else. Occasional dips are normal and usually track sleep, stress and workload. Desire that stays low for months is worth discussing with a clinician.
Low libido usually has several overlapping causes. The most common are short sleep, chronic stress, heavy training with poor recovery, under-eating, alcohol, low mood, relationship strain and medication effects. Hormonal contributors such as low testosterone, high SHBG, raised prolactin, shifting estradiol or thyroid dysfunction explain a smaller share, and a clinician interprets those results in context.
Hormonally, low total or free testosterone, high SHBG, raised prolactin and thyroid disorders can all contribute. Erectile difficulty alongside low desire deserves assessment, since it can be an early cardiovascular signal worth checking.
Six markers carry most of the useful information, namely total testosterone, free testosterone, SHBG, prolactin, estradiol and TSH. Together they show how much androgen you produce, how much is biologically available, whether the pituitary signal is disrupted and whether thyroid function is contributing. A licensed clinician reads them alongside your symptoms and medications.
Yes, and it happens often. Total testosterone can sit mid-range while high SHBG leaves the free fraction low, which is one possible reason symptoms persist. Desire also depends on sleep, mood, stress, relationship context and medication, none of which appear in bloodwork. A normal panel narrows the search rather than ending it.
High SHBG binds more testosterone, which lowers the free fraction available to tissue, so it is one possible contributor to reduced desire. SHBG rises with age, thyroid overactivity, estrogen exposure, liver disease and low energy availability. The result is interpreted next to total and free testosterone rather than on its own.
Yes. Sustained stress and short sleep are among the most common explanations for reduced desire, and both act through mood, fatigue and hormonal signalling at once. Testosterone secretion in men is closely tied to sleep, so several short nights can lower a morning result. Reviews describe low desire as multifactorial rather than purely hormonal.
Seek care promptly if low desire comes with headaches, visual changes, milk production from the nipples, shrinking testicles, breast tissue growth, unexplained weight loss or persistent low mood. Also raise it promptly if it started soon after a new prescription. If you are having thoughts of self-harm, call or text 988 (US) or your local emergency number now.