Tiredness and low mood did not group with a falling level
Nine symptoms popularly pinned on low testosterone were tested in 3369 men. Only three held together as testosterone fell: poor morning erections, low desire, erectile difficulty.
What the study found
Only three symptoms actually clustered with falling testosterone
Nine symptoms popularly pinned on low testosterone were each related to it one at a time. Tested in 3369 men for which held together as testosterone fell, only three survived, and all three were sexual: poor morning erections, low desire, erectile difficulty. Fatigue and low mood did not.
The caveat · Snapshot, not a test of treatment
This is a snapshot, so it can say which symptoms travel with low testosterone and not whether raising it would relieve them. That fatigue and low mood failed to cluster is a statement about how symptoms group, not proof they have nothing to do with testosterone. Testosterone here was measured by mass spectrometry on morning samples, a stricter standard than much routine clinical testing, so the thresholds may not transfer to an ordinary lab result.