There are several causes for primary aldosteronism.

In about 30% cases there is a (usually benign) tumour in the adrenal gland. This is also called Conn’s syndrome. In 60% of cases there is enlargement of both adrenal glands. This is called bilateral adrenal hyperplasia. Sometimes there is enlargement of 1 adrenal gland (unilateral or unilateral adrenal hyperplasia). There are also a number of very rare forms of primary aldosteronism such as a malignant tumour in the adrenal gland that makes too much aldosterone or familial (hereditary) forms of hyperaldosteronism.

Research shows that primary aldosteronism occurs in about 5-10% of people with elevated blood pressure. The probability of the presence of primary aldosteronism increases with the severity of the elevated blood pressure. It is estimated that for 17-23% of people with untreatable elevated blood pressure, primary aldosteronism is the underlying cause.

The most common complaints and symptoms in a primary aldosteronism are:

• Elevated blood pressure
• Muscle weakness
• Muscle cramps
• Headache
• Heart palpitations or cardiac arrhythmias
• Frequent urination, also at night

The elevated blood pressure can eventually damage the kidneys, the heart and the blood vessels. The high levels of aldosterone can also damage the heart and blood vessels. This can result in impaired kidney function, a TIA, a stroke or a myocardial infarction.

Research suggests that people with primary aldosteronism regularly have a reduced quality of life. This is caused in particular by fatigue, pain, difficulty in concentration, sleep disorders and mood disorders.

In order to establish a primary aldosteronism, blood tests are done. Here, the aldosterone and the renin content are measured. In the case of primary aldosteronism, the aldosterone is increased and the renin is low (suppressed).

If the aldosterone is increased and the renin is suppressed, a follow-up study is carried out: the salt load test. This study is carried out on the day of treatment. A saline solution is administered through an infusion into the arm for 4 hours. Blood is taken before and after the administration. The aldosterone hormone is measured in this blood. Normally, the aldosterone drops after administration of the saline solution. In the case of primary aldosteronism, the aldosterone does not or hardly decreases.

Before these two studies can be carried out, certain medicines must be stopped or adjusted first, as they can influence the results. It is also necessary to ensure that the level of potassium salt in the body is normal.

If the above study shows that there is primary aldosteronism, then research is done into the cause. A CT scan of the adrenal glands is made to see if there are abnormalities in one or both adrenal glands. To be able to determine definitively whether one or both adrenal glands are overactive, an adrenal vein sampling is carried out. This study compares the blood from the left and right adrenal veins.

It is very important to know the cause because it affects the choice of treatment.

The treatment of primary aldosteronism depends on the cause and the underlying health condition of the person.

With a unilateral tumour in the adrenal gland (Conn’s syndrome), surgery is usually opted for. This is now done with keyhole surgery. After the surgery, tests are carried out to determine whether the excessive aldosterone levels in the body have been rectified. This is done by measuring the level of aldosterone and renin in the blood, often also followed by a salt load test. The blood pressure and the potassium level in the blood may return to normal after the operation. Sometimes the elevated blood pressure remains, but the medication against high blood pressure can be reduced. Often the high blood pressure has long been present before the diagnosis of primary aldosteronism is made. This could have caused damage, whereby the blood pressure after the operation is no longer (completely) normal.

If there is bilateral adrenal hyperplasia, or if people cannot be operated on, then treatment with medication will be opted for. The most commonly used medication is spironolactone. If spironolactone is not tolerated properly, eplerenone is administered. Sometimes other medications are also needed to lower blood pressure and improve blood potassium levels.