What is primary hyperaldosteronism?
In primary hyperaldosteronism, too much of the hormone aldosterone is produced in the adrenal glands. The aldosterone hormone affects the water and salt balance in the body. With excessive levels of aldosterone, elevated blood pressure and low levels of potassium salt can occur in the body.
What are the causes of primary hyperaldosteronism?
There are several causes for primary hyperaldosteronism.
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 hyperaldosteronism such as a malignant tumour in the adrenal gland that makes too much aldosterone or familial (hereditary) forms of hyperaldosteronism.
How often does primary hyperaldosteronism occur?
Research shows that primary hyperaldosteronism occurs in about 5-10% of people with elevated blood pressure. The probability of the presence of primary hyperaldosteronism increases with the severity of the elevated blood pressure. It is estimated that for 17-23% of people with untreatable elevated blood pressure, primary hyperaldosteronism is the underlying cause.
What are the effects of primary hyperaldosteronism?
The most common complaints and symptoms in a primary hyperaldosteronism are:
- Elevated blood pressure
- Muscle weakness
- Muscle cramps
- 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 hyperaldosteronism regularly have a reduced quality of life. This is caused in particular by fatigue, pain, difficulty in concentration, sleep disorders and mood disorders.
How is primary hyperaldosteronism diagnosed?
In order to establish a primary hyperaldosteronism, blood tests are done. Here, the aldosterone and the renin content are measured. In the case of primary hyperaldosteronism, 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 hyperaldosteronism, 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 hyperaldosteronism, 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.
How is primary hyperaldosteronism treated?
The treatment of primary hyperaldosteronism 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 hyperaldosteronism 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.