Testosterone is the most important male sex hormone. It influences muscle, bone, drive, mood and sexual function. From around age 40 it falls slowly and naturally, by roughly one to two percent per year, which is why German endocrinologists say there is no sudden "male menopause".
A real Testosteronmangel is more than a low number. Doctors speak of a deficiency when two things come together: clear symptoms, for example persistent tiredness, low sex drive, loss of muscle or low mood, and repeatedly low values in blood samples taken in the morning. The morning matters because testosterone is highest early in the day and falls towards the evening, so an afternoon value can look falsely low. A single measurement is never enough for the diagnosis.
Several everyday factors push testosterone down, including being overweight, poor sleep, heavy alcohol use and some illnesses and medicines. Sometimes the value recovers when those change.
If the signs sound familiar, the right path is a doctor, usually a urologist or endocrinologist, who can measure properly and rule out other causes. Testosterone products without a confirmed deficiency and a prescription are a bad idea, and buying them on your own is risky.
In this glossary, the Nüchternblutabnahme explains morning blood draws, and the Referenzbereich explains how to read the range next to your value.
This glossary entry is general information, not medical advice, and it is not intended to diagnose, treat or rule out any condition. Discuss your own results with a clinician who knows your history.
