Charcoal reliably traps substances in the gut. Its strongest role is binding swallowed drugs and poisons in emergencies. It can lower certain gut-derived waste products when kidneys fail, with weaker signals for gas and cholesterol. Whether this slows disease or extends life is unsettled. The same non-selective binding blunts nutrients and medicines, causing constipation and dark stools. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Serum indoxyl sulfate | As low as achievable; < ~0.6 mg/dL total | Primary target of the kidney-toxin use; tracks binding effect |
| Estimated glomerular filtration rate (eGFR) | > 60 mL/min/1.73 m² | Gauges kidney function and whether toxin-binding is warranted |
| Serum creatinine | ~0.6–1.1 mg/dL | Complements eGFR for kidney trajectory |
| Fat-soluble vitamins (A, D, E, K) | Mid-normal or better (e.g., vitamin D 40–60 ng/mL) | Detects depletion from chronic non-selective binding |
| Serum potassium | 4.0–4.5 mmol/L | Screens for electrolyte shifts, esp. with cathartic use |
| Serum phosphate | 2.5–4.5 mg/dL | Relevant in kidney disease and with binder stacking |
| Ferritin / iron studies | Ferritin ~50–150 ng/mL | Iron is poorly bound but chronic use plus poor intake can lower stores |
| LDL cholesterol | < 100 mg/dL (lower if higher risk) | Tracks the cholesterol-binding effect if that is a goal |
Cadence: Chronic users: reassess at ~3 months after starting, then every 6–12 months. Kidney-toxin use: toxin and kidney markers every 1–3 months early on.