What Time of Day Should I Take My Testosterone Test?

Short answer: between 7am and 10am, before a meal where possible, and not after a poor night's sleep or recent illness. Testosterone has a strong circadian rhythm; testing at the wrong time can produce a false-low result.

1Why timing matters

Testosterone peaks in the morning (highest typically between 7am and 10am) and declines through the day. By afternoon, levels can be 25–35% lower than morning peaks in healthy young men. Clinical guidelines (Endocrine Society, AUA) recommend morning sampling for this reason.

2Other factors that affect accuracy

• Sleep: a recent night of significantly restricted sleep can lower the result
• Recent illness: acute illness can transiently suppress testosterone
• Severe exercise the day before: can lower the result
• Fasting: not strictly required for testosterone alone, but often requested if other tests (glucose, lipids) are run alongside
• Time of year: minor seasonal variation in some studies

3When a single result isn't enough

A single low morning result should be repeated on a separate morning to confirm before any treatment decision. Day-to-day variation is real and a single number isn't a diagnosis.

4When to see a doctor

A Singapore-licensed doctor on Noah can arrange testing through partner laboratories. Book a confidential consultation here.

5References

Bhasin S, et al. Endocrine Society Clinical Practice Guideline. JCEM. 2018.

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