An adrenal washout calculator is a tool for calculating the ratio of cortisol and adrenaline in the body. This can assess adrenal fatigue, which is the most common hormone deficiency. An adrenal washout calculator is primarily used to diagnose adrenal adenoma. You can estimate adrenal lavage with a non-contrast scan, a contrast or 60-75 second scan, and a 15-minute delayed scan.

What is adrenal washout?

Adrenal lavage is a hormone replacement therapy. It is used to replace hormones not produced by the adrenal glands. You can use this therapy in treating adrenal insufficiency when the adrenal glands cannot produce hormones cortisol and aldosterone. These hormones are necessary for the body to function correctly. Symptoms of adrenal insufficiency include extreme fatigue, lack of concentration, low blood pressure, low blood sugar, and weight loss.

The most common cause of adrenal insufficiency is when the body’s immune system attacks the adrenal glands. This can happen in people who have an autoimmune disorder, such as lupus or type 1 diabetes. Other causes of adrenal insufficiency include:

  • certain types of cancer,
  • taking medications that suppress the adrenal glands, and
  • having had an adrenal gland removed.  

Side effects of this therapy include diarrhea, nausea, vomiting, and abdominal pain.

Our calculator is easy to use, taking into account age, weight, and symptoms. A ratio of greater than 10 is standard, with symptoms of adrenal fatigue being most pronounced at ratios of less than 5.

Adenomas are the most common benign lesions of the adrenal glands. In most cases, these are severely limited formations of the adrenal cortex. They are most often homogeneous display as 8.9. They have an average size 2 – 2.5cm at the time of detection.

The process of rinsing the adrenal glands consists of the following elements:

  • Contrast-free scanning,
  • Contrast-enhanced scanning that can be delayed by 60 to 75 seconds,
  • Delayed scanning averages 15 minutes. 

Washout interpretations

Interpretation of the following elements:

  • Absolute washout ≥ 60% and relative lavage ≥ 40% – after 15 min is considered characteristic of adenoma. A sensitivity is between 86 and 95%. A specificity is between 92 and 97% for absolute washout.
  • Relative washout ≥ 40% – shows a sensitivity of 96% and a specificity of 100% in the diagnosis of adenomas.
  • In contrast to pheochromocytoma adenomas, it achieves high HU values (> 150) after applying a contrast agent.
  • Density ≤ 0 HU native cross-sections are more critical than leaching characteristics if they are inclusive. As uncalcified lesions are native values ≥ 43 HU, without the presence of hemorrhage.
  • Finally, flushing characteristics do not work in diagnosing inhomogeneous lesions with large areas of necrosis or bleeding.

Adrenal washout formulas

We use two formulas to rinse the adrenal glands. It can refer to absolute rinsing and relative rinsing. Below we will explain how to use both formulas and how to interpret the values:

Aw = 100\cdot \frac{P_{HU}-D_{HU}}{P_{HU}-Pre_{HU}}

When the absolute washout is greater than 60%, it strongly indicates an adenoma of the adrenal gland.

Rw = 100\cdot \frac{P_{HU}-D_{HU}}{P_{HU}}

When the relative washout is greater than 40%, it indicates an adenoma of the adrenal gland.

Absolute – absolute rinsing,
Relative – relative rinsing.

PHU (Post HU) – postcontrast Hounsfield units,
DHU (Delayed HU) – delayed Hounsfield unit phase,
PreHU (Before HU) – precontrast Hounsfield units.

Hounsfield Unit-HU is a relatively quantitative measurement of radiology density used to interpret CT images.

Practical points and limitations of washout imaging

Washout imaging is a medical imaging technique used to identify and diagnose various types of medical conditions. You can use this technique to identify and diagnose heart disease. Also, it can identify other health conditions. Use flushing imaging combined with other imaging techniques, such as X-rays or CT scans.

This technique can be challenging because it requires specialized equipment, which not all hospitals have. Furthermore, the patient must be able to lay still for the test duration. The patient must also have no contact with anything for at least two hours before the test.

The washout imaging is the newest in brain imaging technology. It is a new technique that has emerged in the last few years. This radiology, in-vivo MRI technique is performed by injecting a bolus of gadolinium-based contrast agent into the bloodstream. The gadolinium-based contrast agent is typically injected into the left arm and then travels to the right side of the brain, where the MRI scanner detects it.

This contrasts with most MRI scans, which rely on static images to create a 2D picture of the brain. Washout imaging relies on movement in the brain to create a 3D view of the brain. This new technique has many benefits. It is swift, with scan times as short as 2 minutes.

Adrenal adenoma

An adrenal adenoma is a benign tumor of the adrenal gland. These tumors are usually about 1-2 cm in size, and their place is in the outer part of the gland. Adrenal adenomas may secrete hormones, which can cause problems in the body. The most common symptom of an adrenal adenoma is Cushing’s syndrome, caused by the overproduction of cortisol.

In patients with adenoma of the adrenal gland, the prognosis is extremely good. It is much more common in women than in men. No-functional adenomas of the adrenal gland rarely need treatment. The prevalence of adrenal incidentaloma based on CT scan findings ranges from 0.35% to 2.3%.

Abdominal CT scan - arrow depicts right adrenal mass
Abdominal CT scan – arrow depicts right adrenal mass

Adrenal calculator – a practical example

With the following values, use our calculator to calculate an example of adrenal lavage.

Pre-contrast: 22 HU
Post-contrast: 182 HU
Delayed phase: 102HU

Calculating absolute adrenal washout using the formula: 

Aw = 100\cdot \frac{182-102}{182-22} = 100\cdot \frac{80}{160} = 100\cdot 0.5 = 50%

Calculating relative adrenal washout using the formula:

Rw = 100\cdot \frac{182-102}{182} = 100\cdot \frac{80}{182} = 100\cdot 0.43 = 43%


1. What does adrenal washout mean?

Adrenal washout is a diagnostic procedure used to assess the function of the adrenal glands. The process involves injecting a contrast agent (dye) and an isotope. The contrast agent helps the doctor visualize the blood flow in the adrenal gland. The isotope allows the doctor to see how well the gland functions. You do the procedure with a scan called a CT or PET scan.

2. How is washout calculated?

To obtain the result of adrenal lavage, use adrenal mass density values ​​on the non-amplified portal venous phase and CT scan with 15 delays (density is measured in Hounsfield units -HU). The original use was for the diagnosis of adrenal adenoma.