What is Cosyntropin: Uses, Dosage, Side Effects and More

Cosyntropin is a synthetic version of a hormone that helps doctors test how well your adrenal glands are working. Your adrenal glands sit on top of your kidneys and make important hormones like cortisol, which helps your body handle stress and maintain blood pressure. When doctors need to check if these glands are functioning properly, they use cosyntropin to stimulate them and see how they respond.

What is Cosyntropin?

Cosyntropin is a man-made copy of a natural hormone called ACTH (adrenocorticotropic hormone). It's designed to mimic what your pituitary gland normally does when it signals your adrenal glands to produce cortisol. This synthetic hormone contains the most active part of natural ACTH, making it perfect for medical testing.

The medication comes as a white powder that gets mixed with a special liquid right before your doctor injects it. You'll typically receive this injection in a hospital or clinic setting where medical professionals can monitor your response closely.

What is Cosyntropin Used For?

Cosyntropin helps doctors diagnose problems with your adrenal glands through a test called the ACTH stimulation test. This test can reveal whether your adrenal glands are producing enough cortisol or if they're not responding properly to hormonal signals.

Doctors most commonly use this test when they suspect conditions like Addison's disease, where your adrenal glands don't make enough cortisol. They might also use it to check for secondary adrenal insufficiency, which happens when your pituitary gland doesn't send the right signals to your adrenal glands.

Sometimes, your doctor might recommend this test if you've been taking steroid medications for a long time. Long-term steroid use can sometimes affect how well your natural hormone system works, and this test helps determine if your adrenal glands have recovered their normal function.

How Does Cosyntropin Work?

Cosyntropin works by acting like a gentle wake-up call to your adrenal glands. When injected, it travels through your bloodstream and binds to special receptors on your adrenal glands, just like natural ACTH would do.

This binding triggers your adrenal glands to release cortisol into your bloodstream. In healthy people, cortisol levels should rise significantly within 30 to 60 minutes after the injection. Your doctor will take blood samples before and after the injection to measure how much cortisol your adrenal glands produced.

The test is considered quite reliable because cosyntropin is a strong stimulator of cortisol production. If your adrenal glands are working normally, they should respond robustly to this synthetic hormone.

How Should I Take Cosyntropin?

You won't take cosyntropin yourself - it's always given by a healthcare professional in a medical setting. The injection is typically given into a muscle (intramuscular) or into a vein (intravenous), depending on what your doctor prefers and what type of test you're having.

Before your test, you don't need to fast or avoid eating, but your doctor might ask you to avoid certain medications for a few days. Some drugs, especially steroids, can interfere with the test results, so it's important to tell your doctor about all medications you're taking.

The injection itself usually doesn't hurt more than a typical shot. You might feel a slight pinch when the needle goes in, but the discomfort passes quickly. After the injection, you'll need to stay in the medical facility for about an hour so your doctor can take follow-up blood samples.

How Long Should I Take Cosyntropin For?

Cosyntropin is only used once during your diagnostic test - it's not a medication you take regularly or over time. The entire testing process usually takes about one to two hours from start to finish.

Your doctor will give you the injection and then monitor your response by taking blood samples at specific time intervals. Most commonly, they'll take samples at 30 minutes and 60 minutes after the injection to see how your cortisol levels change.

If your doctor needs to repeat the test for any reason, they'll schedule it as a separate appointment. This might happen if the first test results were unclear or if they need to monitor your adrenal function over time.

What Are the Side Effects of Cosyntropin?

Most people tolerate cosyntropin very well, and serious side effects are quite rare. The most common side effects are mild and temporary, typically lasting only a few hours after the injection.

Here are the side effects you might experience, starting with the most common ones:

• Mild nausea or stomach discomfort
• Slight dizziness or lightheadedness
• Temporary flushing or warmth in your face
• Minor irritation at the injection site
• Mild headache

These common side effects usually resolve on their own within a few hours and don't require any special treatment.

More serious side effects are uncommon but can include allergic reactions. Here are the rare but more concerning symptoms to watch for:

• Severe allergic reactions with difficulty breathing or swelling
• Rapid or irregular heartbeat
• Severe dizziness or fainting
• Intense nausea or vomiting
• Chest pain or tightness

If you experience any of these serious symptoms, your medical team will address them immediately. This is why the test is always performed in a medical setting where help is readily available.

Who Should Not Take Cosyntropin?

Cosyntropin is generally safe for most people, but there are some situations where your doctor might choose a different testing method or take extra precautions during the test.

You should tell your doctor if you have any of these conditions before receiving cosyntropin:

• Known allergies to cosyntropin or similar medications
• Severe heart problems or recent heart attack
• Uncontrolled high blood pressure
• Active infections or serious illness
• Pregnancy or breastfeeding

Your doctor will carefully weigh the benefits and risks if you have any of these conditions. In many cases, they can still perform the test safely with appropriate monitoring and precautions.

If you're taking certain medications, especially steroids or drugs that affect hormone levels, your doctor might ask you to stop them temporarily before the test. This helps ensure the most accurate results possible.

Cosyntropin Brand Names

Cosyntropin is available under several brand names, with Cortrosyn being the most commonly used one in the United States. You might also encounter it under names like Synacthen in other countries.

Regardless of the brand name, all versions of cosyntropin contain the same active ingredient and work in the same way. Your doctor or pharmacy will let you know which specific brand they're using for your test.

Cosyntropin Alternatives

While cosyntropin is the most commonly used medication for testing adrenal function, there are a few alternatives your doctor might consider in certain situations.

The insulin tolerance test is another way to check adrenal function, but it's more complex and carries higher risks. Your doctor might also use other blood tests or imaging studies to evaluate your adrenal glands, depending on your specific situation.

In some cases, your doctor might recommend monitoring your natural cortisol levels throughout the day instead of using a stimulation test. This approach can be helpful when the cosyntropin test results are unclear or when you can't safely receive the injection.

Is Cosyntropin Better Than Other Adrenal Function Tests?

Cosyntropin testing is considered the gold standard for diagnosing primary adrenal insufficiency because it's both accurate and relatively safe. It provides clear, reliable results that help doctors make confident diagnoses.

Compared to other tests like the insulin tolerance test, cosyntropin is much safer and easier to perform. The insulin tolerance test can cause dangerously low blood sugar levels, while cosyntropin rarely causes serious side effects.

The cosyntropin test is also more convenient than measuring natural cortisol levels throughout the day, which requires multiple blood draws and can be affected by stress, illness, or daily activities. With cosyntropin, your doctor gets a clear picture of your adrenal function in just one visit.