Phosphorus, an essential dietary mineral for bone and cell energy, is also sold as phosphate salt supplements to correct deficiency or aid endurance. Modern diets rarely run short, so the question is avoiding excess. Evidence is strongest for harm from added and concentrated phosphate, moderate for long-term harm from high intake and for weight control, and weak for performance and bone gains. Moderate whole-food intake carries little risk. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Serum phosphate (fasting) | 3.0–3.8 mg/dL (0.97–1.23 mmol/L) | Status and excess |
| Serum calcium | 9.2–10.0 mg/dL | Calcium–phosphate balance |
| eGFR (estimated glomerular filtration rate, a measure of kidney filtering) | Above 90 mL/min/1.73 m² | Kidney phosphate clearance |
| PTH (parathyroid hormone) | 15–45 pg/mL | Hormonal response to phosphate load |
| 25-hydroxyvitamin D | 40–60 ng/mL | Drives phosphate absorption |
| FGF23 (intact; fibroblast growth factor 23, a bone-made hormone) | No established target; track change from own baseline | Early signal of phosphate excess |
| 24-hour urine phosphate | No established target; roughly 60–70% of intake appears in urine | Estimates actual intake including additives |
| Serum potassium | 4.0–5.0 mmol/L | Safety with potassium phosphate |
| Coronary artery calcium score | 0 | Structural check for vascular calcification |
Cadence: Baseline before any supplement, loading cycle or major intake change. Repletion: serum phosphate, calcium and potassium at 1 and 4 weeks, then every 3 months. Long-term therapy: PTH, eGFR and urine calcium every 6 months; kidney ultrasound yearly. Intake management in healthy adults: fasting serum phosphate, PTH and eGFR every 6–12 months.