Clinical Investigations Unit (CIU) - Services

Adrenocorticotropic Hormone (ACTH) Stimulation Test

What is an ACTH stimulation test?

This is a test ordered by your endocrinologist to see if your adrenal glands are able to make enough cortisol. Adrenal glands are located on top of your kidneys and are responsible for making hormones. Cortisol is one of these hormones. It assists in regulating your metabolism and helps your body to respond to stress. This test is performed to see if your adrenal glands can respond appropriately after stimulation by Cosyntropin (synthetic form of ACTH). It is used to test for adrenal insufficiency or non-classic (late onset) congenital adrenal hyperplasia.

How is the test performed?

An appointment will be scheduled for you to have the test performed. You will be provided with the location and arrival time. Please plan for at least 3 hours of testing.

An intravenous (IV) cannula will be inserted into a vein in one of your arms and will remain there for the duration of the test. All of your blood samples will be drawn through this catheter, so you will not require any further needle pokes. Once the first blood tests are obtained, the nurse will inject Cosyntropin into the IV line. Cosyntropin is a synthetic version of ACTH (adrenocorticotropic hormone), which your pituitary gland releases to stimulate the adrenal glands to make cortisol.

After the medication is injected, the nurse will withdraw blood samples from the IV line every 30 minutes for 1-2 hours, according to the directions from your endocrinologist. Once this is completed, the IV line will be removed and you will be able to go home.

Are there any risks or side effects to this test?

As with any blood test or IV insertion, you may have some bruising or redness at the site where the catheter was inserted. There is also a very small risk of infection.

The Cosyntropin may cause a brief period of side effects such as nausea, flushing and increase blood pressure. The nurse will give you medication slowly– over about 2 minutes – to minimize these effects, and will monitor your blood pressure. These side effects will disappear after a few minutes and you will feel well for the remainder of the test.

How do I prepare for the test?

You will need to fast (no food or drinks other than water) after 10:00 pm the night before your test. Please DO drink water the morning of the test. You can bring a snack to eat once the test is completed.

Your doctor may also want you to take dexamethasone at 11:00 pm the night before the test. This will be discussed with you at your clinic appointment and tablets or a prescription will be given to you at that time.

Ask your doctor if there are any medications you should stop prior to your test and when you should restart them.

What should I do if I need to cancel?

If you need to cancel your appointment, please call 519-646-6000 ext. 66043 and state your name and test date. It’s important to know that there may be a delay in rescheduling your appointment as the availability of test times are limited. If you need to cancel, we ask that you call as soon as possible.

Download the above ACTH Stimulation Test information (PDF) from our Patient and Caregiver Resources

Saline Infusion for Primary Hyperaldosteronism Test

What is a saline infusion for primary hyperaldosteronism test?

This test is frequently done for patients who have high blood pressure that has not responded appropriately to medication, and for those with low blood potassium levels.

It is being done because your previous blood work showed a high level of aldosterone. Aldosterone helps control blood pressure by holding onto salt and water. The increased salt and water increases your blood pressure. Aldosterone also helps eliminate potassium from the blood.

Primary hyperaldosteronism is a disease in which the adrenal gland(s) make too much aldosterone, leading to high blood pressure and low blood potassium levels.

How is the test performed?

An appointment will be scheduled for you to have the test performed. You will be provided with the location and arrival time. Please plan for at least 5 hours of testing.

Upon arrival, your weight will be taken and you will recline in a lying position for 30 minutes prior to the start of your test.

An intravenous (IV) cannula will be inserted into a vein in one of your arms and will remain there for the duration of the test. All of your blood samples will be drawn through this catheter, so you will not require any further needle pokes.

Using an infusion pump, the IV fluid is delivered into a vein of your arm at a very fast rate for 4 hours. Your arm may feel cold.

During the IV infusion, the nurse will check your blood pressure every 15 minutes and check you for any signs that you are nor tolerating the large volume of fluid, such as swelling in your hands and feet, shortness of breath or cough. Once the infusion is done, blood work will be drawn from the IV line. The IV will continue very slowly until it is determined you have been able to get rid of most of the fluid you have received.

You will be asked to empty your bladder and your weight will be rechecked. If you have any signs of retaining too much fluid, the doctor will assess you and may provide IV medication, furosemide (Lasix), to help you pass urine to eliminate the extra fluid. The physician will also advise you about what blood pressure pills and doses to take after the test is done.

Once the blood work is done, your blood pressure is stable and next steps have been discussed, the IV will be discontinued and you can go home.

Are there any risks or side effects to this test?

As with any blood test or IV insertion, you may have some bruising or redness at the site where the catheter was inserted. There is also a very small risk of infection.

How do I prepare for the test?

Your test will be booked to allow for about 4 weeks of preparation. During this period, you will likely have your blood pressure medications changed and doses adjusted as many of blood pressure medications can affect the blood tests, which will impact results.

Your doctor may order blood tests to monitor potassium levels. You may also be started on a potassium supplement or have it increased as low blood potassium levels will also give invalid test results. You may also have heart tests done to ensure your heart is able to tolerate the volume of salty IV fluid given during this test.

What should I do if I need to cancel?

If you need to cancel your appointment, please call 519-646-6000 ext. 66043 and state your name and test date. It’s important to know that there may be a delay in rescheduling your appointment as the availability of test times are limited. If you need to cancel, we ask that you call as soon as possible.

Download the above Saline Infusion for Primary Hyperaldosteronism Test (PDF) from our Patient and Caregiver Resources.

Mixed Meal Tolerance Test

What is a mixed meal tolerance test?

The mixed meal tolerance test requires a person to drink a “mixed meal”, which is usually Ensure High Protein drink that contains protein, carbohydrates and fat. The goal of the test is to measure how much insulin your pancreas makes in response to food. When a person’s body is working appropriately, the beverage causes blood sugar to rise and the pancreas to release just enough insulin to normalize blood sugar. However, in certain circumstances, the pancreas may work differently and produce too much or too little insulin.

This test is often used for people who have had an islet or pancreas transplant to determine if the transplanted cells are making enough insulin.

This test is also used for people who experience a low blood sugar level following a meal.

How is the test performed?

An appointment will be scheduled for you to have the test performed. You will be provided with the location and arrival time. Please plan for at least 2 hours of testing.

On arrival your weight and blood sugar will be tested. The nurse will continue testing your sugars from the finger poke as needed. An intravenous (IV) cannula will be inserted into a vein in one of your arms and will remain there for the duration of the test. All of your blood samples will be drawn through this catheter, so you will not require any further needle pokes. The nurse will take blood samples approximately every 30-60 minutes after you have consumed an amount of Ensure based on your body weight.

Once the test is completed, the IV will be removed and you will be able to go home.

Are there any risks or side effects to this test?

As with any blood test or IV insertion, you may have some bruising or redness at the site where the catheter was inserted. There is also a very small risk of infection.

You may feel light-headed, nauseated and sweaty if your blood sugar level gets very low.

How do I prepare for the test?

You will need to fast (no food or drinks other than water) after 10:00 pm (or as instructed by your doctor) the night before your test. Please DO drink water the morning of the test.

If you are taking insulin, please follow your doctor’s instructions about how to manage your insulin in preparation for the test.

What should I do if I need to cancel?

If you need to cancel your appointment, please call 519-646-6000 ext. 66043 and state your name and test date. It’s important to know that there may be a delay in rescheduling your appointment as the availability of test times are limited. If you need to cancel, we ask that you call as soon as possible.

Download the above Mixed Meal Tolerance Test (PDF) from our Patient and Caregiver Resources.

Levothyroxine Absorption Test

What is a levothyroxine absorption test?
This is a test ordered by your endocrinologist to identify if your body can sufficiently absorb thyroxine after it is administered orally.

How is the test performed?
An appointment will be scheduled for you to have the test performed. You will be provided with the location and arrival time. Please plan for at least 2.5 hours of testing.

An intravenous (IV) cannula will be inserted into a vein in one of your arms and will remain there for the duration of the test. All of your blood samples will be drawn through this catheter, so you will not require any further needle pokes. Once the first blood tests are obtained, the nurse will administer levothyroxine for you to take with a glass of water.

After the medication is taken, the nurse will withdraw blood samples from the IV line every 30 minutes for 1-2 hours, according to the directions from your endocrinologist. Once this is completed, the IV line will be removed and you will be able to go home.

Are there any risks or side effects to this test?
As with any blood test or IV insertion, you may have some bruising or redness at the site where the catheter was inserted. There is also a very small risk of infection.

How do I prepare for the test?
You will need to fast (no food or drinks other than water) after midnight the night before your test. Please DO drink water the morning of the test. You can bring a snack to eat once the test is completed.

What should I do if I need to cancel?
If you need to cancel your appointment, please call 519 646-6000 ext. 66043 and state your name and test date. It’s important to know that there may be a delay in rescheduling your appointment as the availability of test times are limited. If you need to cancel, we ask that you call as soon as possible.

Cortisol Day Curve Test

(CORTISOL SALIVA AND SERUM HOURLY X 8 HOURS)

What is a cortisol day curve test?

This is a test ordered by your endocrinologist to assess your cortisol levels over the course of 8 hours.

How is the test performed?

An appointment will be scheduled for you to have the test performed. You will be provided with the location and arrival time. Please plan for at least 8 1/2 hours of testing.

An intravenous (IV) cannula will be inserted into a vein in one of your arms and will remain there for the duration of the test. All of your blood samples will be drawn through this catheter, so you will not require any further needle pokes.

You will also be asked to provide multiple timed saliva samples that will also be tested for cortisol and compared to the levels in your blood.

Once all the samples have been completed, the IV line will be removed and you will be able to go home.

Are there any risks or side effects to this test?

As with any blood test or IV insertion, you may have some bruising or redness at the site where the catheter was inserted. There is also a very small risk of infection.

How do I prepare for the test?

You will need to fast (no food or drinks other than water) after 10:00 pm the night before your test. Please DO drink water the morning of the test. You can bring snacks to eat once the test has started. If you are taking hydrocortisone, you should take this as you normally do at home, unless otherwise instructed by your physician.

What should I do if I need to cancel?

If you need to cancel your appointment, please call 519 646-6000 ext. 66043 and state your name and test date. It’s important to know that there may be a delay in rescheduling your appointment as the availability of test times are limited. If you need to cancel, we ask that you call as soon as possible.