Aldosterone Suppression Test

Why am I having this test?

• This test is used for the confirmation or exclusion of primary hyperaldosteronism (raised aldosterone levels) a rare cause of high blood pressure.
• You may have been told that you have high blood pressure (hypertension) or low potassium levels in your blood (hypokalaemia).

Who carries out this procedure?

A nurse who specialises in endocrinology is responsible for carrying out this procedure.

What do I need to do before the test?

• Your specialist doctor/nurse may stop or change your blood pressure tablets before the test, as they may interfere with the results. You will be advised of this if necessary in your appointment letter.
• If a change of medicine is required, close monitoring of your blood pressure is necessary either at your GP’s surgery or using a home blood pressure monitor. You will need to contact the nurse with your blood pressure readings who will then discuss with you if any changes in your medicine are required.
• You may be asked to have a blood test to check your potassium level prior to the test. It is important that your potassium level is within normal range to make sure that the test results are accurate. If your potassium level is on the low side, the endocrine nurses will arrange for you to take the appropriate dose of potassium supplements until the test is complete.
• All other medicine should be taken as usual.
• You may eat and drink as usual before and during the test.

Where is the test carried out?

• You will be sent a letter with details of the test and which department you will need to attend.
• If you wish you may bring a companion with you. They may stay with you during the test.

How long will the test take?

• The test will take approximately 5 hours to complete.
• During the course of the test, the nurse will make sure you are comfortable. The nurse will be available in the department during the test.
• On completion of the test, the nurse will give you advice about what to do about your blood pressure medicines.

What happens during the test?

• On arrival you will meet the nurse who is responsible for the test. The nurse will explain the test and you will be given the opportunity to ask questions prior to the start of the test.
• A cannula, a fine plastic tube, is inserted into a vein in your arm. There may be some discomfort for a few seconds. This is used to take blood samples and for the intravenous fluids (a drip).
• After lying on the couch/bed for 30 minutes, with no more than 2 pillows, a blood sample will be taken, and your blood pressure and pulse checked by the nurse. You should continue to lay down for the remainder of the test.
• You will be given an intravenous infusion of normal saline into a vein which will last for 4 hours in total.
• Going to the toilet during the test is allowed but should be avoided during the final 30 minutes of the infusion.
• You may eat and drink as usual during the test.
• After the intravenous infusion is complete, a further blood sample will be taken and your blood pressure and pulse checked.
• The test is then complete.

Are there any side effects?

• Rarely patients may become short of breath. If this happens, you should inform the nurse immediately.
• If changes are made to your blood pressure medicines prior to the test there is a risk of high blood pressure.

What happens after the test?

• At the end of the test the cannula will be removed and a small dressing applied. The dressing can be removed once you get home.
• The results will be discussed at your next clinic visit or will be communicated to you and your GP by letter.
• The nurse looking after you will arrange a further appointment as required.
• The nurse will advise you when to restart any medicines that were stopped prior to the test.
• If you have had to change any medicines prior to the test, you will be advised when to have your blood pressure checked by the nurse.
• After the test you will be safe to resume your normal activities.

If you require more details please contact the Specialist Nurses in Endocrinology:
Tel: 01274 382019 Monday – Friday between 8.00am and 4.00pm except Bank Holidays