Research library
The research library
Every primary source behind a claim on this site, tier-graded for provenance and tagged for the strength of the evidence it carries.
- Sources indexed
- 221
- Peptides covered
- 44
- Tier 1 share
- 100%
- Matching filter
- 1
F·Filter
Reset allT1·Peer-primary literature
Randomized trials, peer-reviewed primary studies, and meta-analyses — the load-bearing layer of the corpus.
1 source
- 2010Cohortstrongn=3,369
Identification of Late-Onset Hypogonadism in Middle-Aged and Elderly Men
Wu FC, Tajar A, Beynon JM, +18 · New England Journal of Medicine
Of nine candidate symptoms tested against the testosterone gradient, only three — poor morning erection, low libido, and erectile dysfunction — clustered syndromically with low testosterone, and the prevalence of symptom-and-biochemistry-confirmed late-onset hypogonadism in men aged 40–79 was approximately 2.1%.