Mass Balance & Excretion Calculator
Summarize parent and metabolite recovery in urine and feces as percent administered dose.
Mass balance & excretion results
Enter administered and recovered amounts.
Use the same dose-equivalent basis for the administered dose and every recovered amount. Do not double-count parent or metabolite measurements with total radioactivity. Collection stopping, sample pooling, unidentified components, stability, and analytical recovery remain study-level decisions.
Source: FDA Clinical Pharmacology Considerations for Human Radiolabeled Mass Balance Studies (2024).
Tool Guide
Definition
Mass Balance & Excretion Calculator — Compare administered dose-equivalent with parent and metabolite dose-equivalents recovered in urine and feces to calculate route-specific and identity-specific percent administered dose, total recovery, and unrecovered fraction.
Purpose
(1) Cross-check urine and feces recovery in radiolabeled mass-balance tables (2) Summarize parent and metabolite recovery fractions (3) Calculate total recovery including other collected material (4) Prepare percent-administered-dose values for reports
How to Use
① Choose the dose-equivalent unit shared by the administered and recovered values. ② Enter parent and metabolite recovery for urine and feces. ③ Add non-overlapping other recovery such as cage wash if applicable. ④ Copy route, identity, total, and unrecovered fractions. Do not double-count parent/metabolite sums together with total radioactivity.
Examples
Example) Administered dose-equivalent=100; urine parent=10 and metabolites=20; feces parent=5 and metabolites=55; other=2 → urine=30%, feces=60% → parent=15%, metabolites=75%, other=2% → total recovery=92%, unrecovered=8% Collection stopping and recovery adequacy are not decided automatically.