A laboratory-made copy of a human nerve messenger, sold inside multi-ingredient scalp serums at about a hundred dollars a month. The idea is plausible — wider blood vessels, more cell growth, calmer immunity around hair roots — but every observation comes from laboratory dishes. No human study names this ingredient, and the same messenger suppresses hair pigment. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Ferritin | 70–100 ng/mL | Iron stores gate hair shaft production |
| 25-hydroxyvitamin D | 40–60 ng/mL | Low status tracks with diffuse shedding |
| TSH | 0.5–2.0 mIU/L | Thyroid dysfunction causes diffuse hair loss |
| Serum zinc | 90–130 µg/dL | Deficiency impairs follicular keratin synthesis |
| hs-CRP | <1.0 mg/L | Flags inflammation that both suppresses growth and predicts stinging |
| Complete blood count with haemoglobin | Haemoglobin 13.5–15.0 g/dL (women), 14.5–16.0 g/dL (men) | Anaemia produces diffuse shedding that mimics non-response |
| Free and total testosterone, DHEA-S | Mid-reference for age and sex | Androgen excess in women drives pattern loss the serum cannot offset |
| Hair count and shaft diameter at a fixed 1 cm² vertex site | No established target exists; change from the individual's own baseline | The only direct measure of the outcome being purchased |
Cadence: Baseline panel and fixed-site photography before the first application; photography repeats at 12 and 24 weeks, then every six months; the laboratory panel repeats at six months, or sooner if shedding increases, and annually thereafter once values sit in range.