ACTH Stimulation Test: Diagnosing Adrenal Insufficiency

The ACTH stimulation test is used to determine how the body responds to adrenocorticotropic hormone (ACTH). It helps detect primary, secondary, and tertiary adrenal insufficiency.

When an individual is in a stressful situation, the body releases the ACTH hormone from the pituitary gland. This hormone prompts the adrenal glands to release cortisol, which plays an essential role in managing metabolism, blood pressure, and immune function.

This test enables doctors to understand how the adrenal glands respond in an individual. It is important for diagnosing hormone-related conditions early.

What is an ACTH Stimulation Test?

In an ACTH test, a healthcare provider administers a synthetic form of the ACTH hormone into a muscle or vein. Blood samples are then collected at specific intervals to measure the amount of cortisol in the body. This helps healthcare professionals determine whether the adrenal glands are functioning properly.

The ACTH simulation test is useful for diagnosing Addison’s disease and other conditions related to adrenal insufficiency. It helps identify hormonal imbalances in individuals experiencing symptoms, such as chronic fatigue, low blood pressure, or unexpected weight loss.

With this test, healthcare professionals can detect adrenal disorders early and offer timely medical support. Measuring cortisol levels after the ACTH injection is important for evaluating adrenal and pituitary health.

When is the ACTH Stimulation Test Done?

Doctors usually recommend the ACTH test if they suspect that the adrenal or pituitary gland is not functioning properly, especially when the individual shows signs of unusual cortisol levels. These symptoms may include fatigue, low blood pressure, or sudden weight changes.

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Since cortisol levels tend to peak early in the morning, it is recommended to schedule the test early in the day to ensure accurate results. Doctors may also advise the individual to:

• Eat carbohydrate-rich foods 12 to 24 hours before the test
• Limit physical activity
• Fast for 6 hours before the test (water is allowed)
• Temporarily discontinue medications that can interfere with cortisol readings

The healthcare professional will give specific instructions based on the individual’s medical history. The test is performed in a clinical setting under professional supervision.

Why is the ACTH Stimulation Test Required?

A healthcare professional may recommend the ACTH test if a person shows symptoms such as:

• Chronic fatigue
• Low blood pressure
• Dizziness
• Unexplained weight loss or gain
• Unusual skin pigmentation

These indicate that the body might not be producing cortisol properly. The ACTH test also helps in identifying secondary or tertiary adrenal insufficiency that may be caused by pituitary or hypothalamic dysfunction.

Additionally, doctors may also use the test to monitor patients with known hormonal disorders. It offers insights into the functioning of the adrenal glands over time, as well as whether treatments are effective.

Also know more about chronic fatigue syndrome

What to Expect in Test Results?

Before the ACTH test, a healthcare professional collects blood samples from the individual. After this, the individual receives an ACTH injection, which might contain a synthetic version of the hormone.

A normal response for the ACTH stimulation test would be a rise in cortisol levels from around 13 to 14 mcg/dL. However, the exact values might vary depending on the type of assay and method used.

If cortisol levels remain low even after the injection, it may indicate primary adrenal insufficiency, which is characterised by underactive adrenal glands. If cortisol levels rise slightly or not at all, even if ACTH hormone levels are normal, it might suggest secondary or tertiary adrenal insufficiency, which is related to pituitary or hypothalamic issues.

If someone is experiencing symptoms related to abnormal cortisol levels, it’s important to get tested immediately. Consult a doctor before the ACTH test, and book it easily through the Dr Lal PathLabs app.

FAQs

1. What is the ACTH stimulation test used to diagnose?

The ACTH stimulation test helps diagnose different forms of adrenal insufficiency, including Addison’s disease, as well as secondary or tertiary adrenal disorders caused by pituitary or hypothalamic dysfunction.

2. How long does the ACTH stimulation test take?

The test typically takes about 60 minutes to complete. Blood samples are taken before the ACTH injection, and again at 30 and/or 60 minutes after, to measure cortisol levels.

3. Does one need to fast before an ACTH test?

Fasting is usually not required, but doctors may ask individuals to avoid certain medications or activities before the ACTH test. It’s important to follow the instructions of the healthcare provider.

4. Is the ACTH injection painful?

The ACTH injection may cause mild pain or a stinging sensation at the injection site, usually in the upper arm. Any discomfort is typically temporary.

5. What are considered normal ACTH levels after stimulation?

After stimulation, cortisol levels should typically rise to more than 13 to 14 mcg/dL. However, normal ACTH levels may vary slightly based on the testing method used. Always consult a doctor for interpretation.