Interactive Model
Iron clearance: the serial pathway
Iron exits the brain through a serial pathway: cell to ISF via ferroportin, ISF to CSF via glymphatic flow, CSF to periphery via drainage. Each step declines with age. Adjust parameters to see how comorbidities, genetics, and sex affect the trajectory.
Iron accumulation by compartment
All values normalized to young-adult baseline (1.0×). LIP baseline 0.8 µM (Kakhlon & Cabantchik 2002). ISF baseline ~1.0 µM (Singh 2014). Iron uptake ~0.5 mg/year (Hallgren & Sourander 1958). ISF rises faster than LIP because glymphatic clearance declines earlier (age 30) than ferroportin (age 40).
Serial, not parallel
Net accumulation: ~0.5 mg/year
Ferroptosis phases
When labile iron exceeds 1.2× baseline, cells enter Phase 1 (sublethal stress). Above 1.5×, Phase 2 triggers frank ferroptosis. Both thresholds are illustrative: no direct LIP threshold has been measured in human brain.
Thresholds are assumed
The intervention window
Clearance pathway decline
Both export steps decline with age. Ferroportin: direction confirmed by Raha 2022 and Lupo 2022, but no annualized rate published. Glymphatic: derived from Patterson 2015 Aβ fractional turnover (~60% decline age 30–80), not iron-specific. Both rates (1%/yr Fpn, 1.2%/yr gly) are assumed linear approximations and may overestimate late-life decline.
Rates are assumed
Disease effects stack
Cell-type Fpn export budget
Microglia make up only 10% of brain cells but contribute 25–50% of total Fpn-mediated iron export. Based on Bao 2021 back-calculation and cell-type expression ratios. Confidence: low-moderate (qualitative expression data, one direct measurement).
The microglial bottleneck
Optional extensions
Parameter source
Time to Phase 1
Age 68
Sublethal iron stress
Time to Phase 2
Age 89
Frank ferroptosis
Clearance at 70
52%
Relative to age 30
ISF iron at 70
1.33 µM
Baseline: 1.0 \u00B5M

















