%TRP and TmP/GFR Calculator
Results update as you type. Use Enter to move to the next field.Select the next field to continue.
4 fields are required.
Enter all four concentrations in mg/dL. Use paired serum and urine collection (usually fasting); pediatric applicability requires separate validation.
Enter all four values to calculate.
Was this calculator easy to use?
Your response is saved to improve this site. Calculator inputs and results are not sent.
Thank you! You can recommend this calculator with the share button above.
Equations, 86% branch, and limitations
Equations and units
TRP (fraction) = 1 − (urine phosphate × serum creatinine)/(serum phosphate × urine creatinine). %TRP = 100 × TRP. Use matched concentration units (here mg/dL).
When TRP ≤0.86: TmP/GFR = serum phosphate × TRP. When TRP >0.86: TmP/GFR = serum phosphate × (0.3 × TRP)/(1 − 0.8 × TRP). The choice uses the unrounded TRP, and TmP/GFR retains mg/dL.
Examples (hypothetical)
Serum phosphate 4, serum creatinine 1, urine phosphate 8, urine creatinine 10 (mg/dL): TRP 0.80; %TRP 80%; TmP/GFR 3.20 mg/dL. With urine phosphate 4: TRP 0.90 and TmP/GFR approximately 3.86 mg/dL.
Clinical limits
Collection timing, dietary intake, kidney function and age influence interpretation. This arithmetic does not provide diagnostic classification or treatment decisions. Missing, invalid or out-of-range inputs do not yield a confirmed result.
Review
Original method sources checked 2026-11-10.