Adrenal Washout Calculator

Written by Great Medico

Updated September 24, 2026 •2 min read

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A lab ratio or imaging score can be useful only if you know what it represents. Adrenal Washout Calculator combines the displayed kidney/urology measurements into one focused estimate.

What this calculator does

Adrenal Washout Calculator uses Precontrast attenuation, 60–75 s postcontrast attenuation, and 15 min delayed attenuation to calculate adrenal washout. It is built around the exact fields displayed in this plugin rather than a generic version of the topic. Where supported, it also shows Relative washout so the primary result is easier to place in context. Kidney calculations often depend on paired laboratory samples, stable physiology, and the population in which the equation was validated. Acute changes in kidney function or nonstandard sampling can make an apparently precise number unreliable.

How to use it

Enter or select Precontrast attenuation, 60–75 s postcontrast attenuation, and 15 min delayed attenuation. Use the units offered by the calculator and choose the option that matches the actual clinical or timing situation. Check date entries and laboratory units before relying on the output. For paired blood, urine, or dialysis measurements, use samples and treatment data from the same collection or clinical episode when the formula requires it.

How the calculation works

Absolute washout is (postcontrast attenuation − delayed attenuation) / (postcontrast attenuation − precontrast attenuation) × 100. Relative washout is (postcontrast attenuation − delayed attenuation) / postcontrast attenuation × 100. The calculator reports both percentages from the three CT attenuation measurements.

Example

Using the sample values prefilled in this calculator, the primary result is 71.43 % (Absolute adrenal washout) and Relative washout is 62.5%. This worked example shows how the plugin’s own default inputs flow through the implemented method; replace them with the correct patient, laboratory, imaging, or personal values before interpreting a result.

How to interpret the result

Interpret the output as absolute adrenal washout from the formula implemented here. Compare it with the relevant laboratory, imaging, pathology, or treatment context, and use trends or a validated clinical pathway when appropriate. One calculated value by itself cannot establish the cause of a urologic or kidney problem or predict an individual outcome.

Limitations and notes

Washout calculations depend on a correctly timed adrenal CT protocol, region-of-interest placement, lesion homogeneity, and precontrast/postcontrast values. Modern adrenal-incidentaloma guidance increasingly emphasizes unenhanced attenuation and imaging phenotype; washout thresholds should not be used in isolation to classify every adrenal lesion.