Stool Osmolar / Osmotic Gap
Uses measured stool osmolality and stool electrolytes (same units as lab reports).
Calculator
How it works
The stool osmotic gap compares measured stool osmolality with the contribution of major cations multiplied by two (to account for paired anions).
Limits
Cutoffs vary by reference; laxative use, dilution, and sample quality can mislead. Not a substitute for endoscopy or specialist evaluation.
Educational tool only—not for diagnosis or treatment decisions.