Adrenal Washout Calculator

Adrenal Washout Calculator for Endocrinology. The two percentages use different denominators and should not be interchanged. Acquisition delay is recorded, not mathematically adjusted. A high washout value does not establish benignity or hormonal inactivity, and thresholds from a different protocol should not be imported automatically.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

Absolute washout = 100 x (enhanced minus delayed HU) / (enhanced minus unenhanced HU). Relative washout = 100 x (enhanced minus delayed HU) / enhanced HU. Both are displayed with the entered delay. Enhanced attenuation must be positive and exceed unenhanced attenuation for this combined calculation.

When to use this calculator

Use to cross-check arithmetic from an appropriate CT acquisition with matched homogeneous regions of interest. The 2023 ESE/ENSAT guideline emphasizes limitations in the evidence for washout thresholds. Imaging interpretation requires more than these percentages.

Inputs used

  • Unenhanced, enhanced and delayed CT attenuation in HU
  • Recorded delay after contrast in minutes

Clinical interpretation

The two percentages use different denominators and should not be interchanged. Acquisition delay is recorded, not mathematically adjusted. A high washout value does not establish benignity or hormonal inactivity, and thresholds from a different protocol should not be imported automatically.

Worked example

Unenhanced 22 HU, enhanced 78 HU and delayed 40 HU give absolute washout 3800/56 = 67.857% and relative washout 3800/78 = 48.718%. With 20, 70 and 40 HU, absolute washout is exactly 60%; the tool still does not assign an adenoma diagnosis.

Limitations and safety notes

Zero or nonpositive enhancement denominators are rejected. Very small enhancement can produce unstable percentages; results outside 0-100% are retained with a measurement-review caution. All three attenuation measurements are required; relative-only calculation is not offered. Heterogeneity, timing and clinical context limit inference.

Frequently asked questions

Is exactly 60% an adenoma diagnosis?

No. This implementation reports arithmetic without a benign/malignant label. Evidence, acquisition protocol and the rest of the evaluation matter.

Does recording the delay correct the result for timing?

No. The entered delay is documented beside the result. The tool does not transform one acquisition protocol into another.

References

  • ESE/ENSAT 2023 primary adrenal-incidentaloma guideline; limited evidence for washout thresholds and need for broader imaging/endocrine assessment. https://academic.oup.com/ejendo/article/189/1/G1/7198474

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

Related reviewed calculators