Tubular Reabsorption of Phosphate (TRP) calculator
Result
87.5%
≥85% — Normal reabsorption
How to use it
- 1
Spot urine and serum phosphate + creatinine. All four values from same time-point.
- 2
TRP = 100 − FEPhosphate. FEPh = (UPO4/SPO4) / (UCr/SCr) × 100.
- 3
TRP < 85%. Renal phosphate wasting. Check PTH, FGF-23 if TRP low.
When to use it
- Hypophosphataemia work-up
- Distinguish renal loss (TRP < 85%) from GI malabsorption.
- Hyperparathyroidism
- Primary HPT → ↓TRP, ↑FEPh, ↑Ca.
- Oncogenic osteomalacia
- FGF-23 excess → renal phosphate wasting (TRP < 85%).
A reference for clinicians and students, not medical advice. A score supports a decision; it does not make one. Check every result against the patient in front of you and your local protocol.
At a glance
- Specialty
- Nephrology
- Inputs
- 4
- Type
- Formula
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