Topical adenosine appears to keep follicles in their active growth phase longer and produce thicker strands, working through growth signals rather than blocking hormones. It is gentle and well tolerated, with scalp irritation the only side effect. Evidence is weak and mostly manufacturer-run; thickness gains are more reliable than count. Results take six months and depend on continued use. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Ferritin | 40–70 ng/mL (women); >70 ng/mL often targeted for hair | Low iron stores are a common, correctable cause of shedding that caps response |
| Thyroid-stimulating hormone (TSH) | 0.5–2.5 mIU/L | Thyroid over- or under-activity causes diffuse hair loss |
| Free thyroxine (free T4) | Mid-reference range | Confirms thyroid status alongside TSH when hair loss is diffuse |
| Vitamin D (25-hydroxyvitamin D) | 40–60 ng/mL | Low vitamin D is associated with hair-cycle disruption and poorer response |
| Complete blood count | Within reference range | Screens for anemia and general health issues that manifest as hair loss |
| Total and free testosterone / DHEA-S | Within reference range | Identifies a hormonal driver in women with pattern thinning plus other androgen signs |
Cadence: Standardized photographs and self-assessment at 3, 6, and 12 months; phototrichogram at 6 and 12 months if accessible; then annual review during continued use.