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Low libido evaluation
Short answer: Testing often starts with an early-morning total testosterone when symptoms suggest androgen deficiency. Depending on history and the initial result, a clinician may add free testosterone with SHBG, LH/FSH, prolactin, thyroid tests, glucose or HbA1c and other targeted tests. Blood work cannot independently diagnose stress, depression, relationship factors, sleep problems or medication effects, which are also common contributors to low desire.
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The best test list is based on symptoms and history; ordering every hormone is not automatically more useful.
Early-morning total testosterone is generally the first androgen test when low testosterone is clinically suspected.
A low result usually needs repeat morning confirmation. Free testosterone and SHBG may add context in selected cases.
Prolactin, LH/FSH and thyroid tests may be selected when symptoms or initial hormone results suggest a relevant endocrine pathway.
These are targeted tests, not mandatory screening for every man with low libido.
Glucose or HbA1c, blood count and other tests may be appropriate when diabetes, anaemia, chronic illness or broader symptoms are suspected.
History, sleep, mood and medicines remain essential parts of the evaluation.
Common non-laboratory contributors
Sexual desire is influenced by biological, psychological, relational and situational factors.
Chronic stress and sexual anxiety can reduce desire or make desire feel inconsistent.
Mood conditions can affect interest, arousal and energy, and some treatments may also influence sexual function.
Poor sleep, shift work and sleep disorders may affect energy, mood and hormone patterns.
Some prescribed medicines, alcohol and other substances can affect libido; do not stop medicines without guidance.
Conflict, communication, attraction and sexual expectations may affect desire without excluding physical factors.
Diabetes, obesity, thyroid disease, neurological conditions and chronic pain can influence sexual desire.
Libido is not the same as erection
Libido describes sexual interest, while erectile function describes the ability to achieve and maintain an erection. A man may experience one without the other, so the clinician should clarify which symptom is present and when it began.
Clinical context first
A clinician may ask about morning erections, relationship context, mood, sleep, medicines, alcohol, fertility, weight change and other symptoms before selecting tests. This prevents broad panels from producing unrelated findings that do not explain the complaint.
The StrideRX approach
For men whose low desire occurs with ED or reduced morning erections, ErectAware™ evaluates androgen, pituitary, thyroid, metabolic and vascular context. Results are translated into a doctor-authored Smart Report for specialist discussion.
Get urgent help when needed
Seek prompt professional help for severe depression, thoughts of self-harm, sudden neurological symptoms or another medical emergency. This page is educational and cannot assess an individual diagnosis.
Dr. Varun Arora, MD Psychiatry · Erectile Health Specialist and Specialist Sexologist
Last medically reviewed: 2026-07-17
When low testosterone is suspected, early-morning total testosterone is commonly the first hormone test.
Not always. Total testosterone is generally first; free testosterone and SHBG may help when the total value is borderline or does not match symptoms.
High prolactin can affect sexual desire and the reproductive hormone axis, so it may be checked when symptoms or initial results make it relevant.
Yes, thyroid dysfunction can affect energy, mood and sexual function, but thyroid testing is usually selected based on symptoms and history.
Yes. Sleep, stress, depression, anxiety, medicines, alcohol, relationship context and other factors may contribute.
No. Libido is sexual desire; ED is difficulty achieving or maintaining an erection. They can occur together or separately.
Yes. Some prescribed medicines can affect desire or sexual function. Do not stop them without consulting the prescribing clinician.
Consider evaluation when it is persistent, distressing, new, accompanied by ED or other symptoms, or follows a medicine or health change.