Brief overview
- Symptoms: Mainly symptoms of high blood pressure such as headaches, ringing in the ears, visual disturbances, shortness of breath and reduced performance
- Diagnosis: Blood pressure measurement, measurement of potassium and sodium in the blood, determination of aldosterone and renin levels, various tests on the function of the adrenal cortex, imaging procedures
- Causes: The cause is often an enlargement of the adrenal cortex, a benign or malignant tumor of the adrenal cortex, very rarely the disease is hereditary
- Treatment: Treatment depends on the causes. Antagonists of the hormone aldosterone and antihypertensive drugs are often used, and surgery is often necessary in the case of a tumor.
- Course of the disease: The course and prognosis depend on the cause and, above all, on how well the blood pressure can be controlled and secondary diseases avoided.
- Prevention: Conn’s syndrome cannot be prevented, as the causes of the underlying changes to the kidneys are usually unknown.
What is Conn’s syndrome?
Conn’s syndrome (primary hyperaldosteronism) is a disease of the adrenal glands in which the blood pressure is permanently too high (hypertension). Aldosterone – one of the hormones that regulate the concentration of salts such as sodium and potassium in the blood – plays an important role here. In Conn’s syndrome, the adrenal cortex produces too much aldosterone.
Primary hyperaldosteronism – the body’s own production of too much aldosterone – was first described in 1955 by US physician Jerome Conn. For a long time, experts considered Conn’s syndrome to be a very rare disease. However, it is now thought to be the cause of up to ten percent of all cases of high blood pressure. Diagnosis is not easy, however, as many of those affected do not have conspicuously low potassium levels.
Conn’s syndrome is the most common cause of secondary hypertension – i.e. cases of high blood pressure that are related to a specific underlying disease – accounting for ten percent of all cases. However, primary hypertension, which is caused by an unfavorable lifestyle and hereditary factors, is still the most common.
What are the symptoms of Conn’s syndrome?
The main symptom of Conn’s syndrome is measurable high blood pressure. Primary hyperaldosteronism does not necessarily cause noticeable symptoms. Only some of those affected complain of specific high blood pressure symptoms such as
- Headaches
- Red and warm face
- ringing in the ears
- nosebleeds
- Visual disturbances
- Shortness of breath
- Reduced performance
Many patients report muscle weakness, cramps, cardiac arrhythmia, constipation, increased thirst (polydipsia) and frequent urination (polyuria).
Weight gain is not one of the typical symptoms of Conn’s syndrome, although this is often assumed by those affected.
How is Conn’s syndrome diagnosed?
Conn’s syndrome usually begins with a diagnosis of high blood pressure. It is not uncommon for sufferers to be treated for months or years before a doctor diagnoses Conn’s syndrome. Sometimes it can be recognized by the fact that the high blood pressure is difficult to control with various medications.
Doctors usually diagnose primary hyperaldosteronism when they notice a low potassium level due to typical symptoms or by chance during a blood test. Around one in ten people with Conn’s syndrome has a potassium deficiency (hypokalemia). Potassium is a mineral that fulfills many important tasks in the body, including in the muscles, in digestion and in the regulation of the heart rhythm.
Other blood values also shift in Conn’s syndrome: the sodium level rises, the magnesium level falls and the pH value of the blood shifts slightly into the alkaline range (alkalosis).
The doctor uses the so-called aldosterone/renin quotient to compare the two values. A value above 50 indicates a possible Conn’s syndrome. However, the values fluctuate and are influenced by medication – including high blood pressure medication such as diuretics, beta blockers and ACE inhibitors – so that several hormone tests are often necessary when diagnosing Conn’s syndrome.
To confirm the diagnosis of Conn’s syndrome, a saline load test may be useful. This involves the patient lying still for around four hours and receiving an infusion of a saline solution during this time. In people with a healthy adrenal gland, this ensures that the body reduces aldosterone production and the hormone level drops by half, whereas in Conn’s syndrome, aldosterone production is barely affected.
Sometimes the doctor tests the effect of other active substances on the aldosterone level, for example with a fludrocortisone suppression test and a captopril test.
An orthostasis test is also helpful in the search for the trigger for Conn’s syndrome. In this test, the doctor measures how the renin and aldosterone levels change when the patient rests in bed or spends several hours continuously in an upright position (walking and standing). In the case of adrenal enlargement, the body is better able to regulate hormone production than in the case of an aldosterone-producing adenoma.
Causes and risk factors
Conn’s syndrome is caused by a disorder of the adrenal cortex. This is the outer part of the adrenal glands, two small organs that sit on the upper ends of the two kidneys. The adrenal cortex is one of the most important production sites for various hormones, i.e. important signaling substances in the body. Among other things, it produces the anti-inflammatory and metabolically active cortisol as well as various sex hormones – and aldosterone.
Aldosterone is responsible for regulating blood pressure and the body’s water balance in conjunction with other hormones – renin and angiotensin. Doctors therefore also refer to the renin-angiotensin-aldosterone system, or RAAS for short.
How the RAAS works
Angiotensin I is converted into angiotensin II by another enzyme, the angiotensin-converting enzyme (ACE). This in turn causes the blood vessels to contract, which increases blood pressure. At the same time, angiotensin II stimulates the adrenal cortex to produce aldosterone. Aldosterone ensures that more water and sodium remain in the body. This also increases blood pressure, as the blood volume in the blood vessels increases. As a result, the kidneys are better supplied with blood and release less renin.
Disorders of the adrenal cortex
In Conn’s syndrome, the RAAS becomes imbalanced because the adrenal gland produces too much aldosterone. There are various reasons for this:
- A benign tumor (adenoma) of the adrenal cortex, which produces aldosterone
- A bilateral, slight enlargement of the adrenal glands (bilateral adrenal hyperplasia)
- A unilateral enlargement of one adrenal gland (unilateral hyperplasia)
- A malignant tumor (carcinoma) of the adrenal cortex that produces aldosterone
However, unilateral hyperplasia and adrenal carcinoma are very rare causes of Conn’s syndrome. The main causes are bilateral adrenal hyperplasia and benign adenoma, each accounting for just under 50 percent.
Familial hyperaldosteronism
Treatment
The treatment of Conn’s syndrome depends on the cause in each individual case:
In the case of bilateral adrenal hyperplasia, i.e. an enlarged adrenal cortex on both sides, various medications are helpful. These include above all the aldosterone antagonist spironolactone. It blocks the “docking sites” (receptors) for aldosterone and thus prevents the kidneys from excreting more potassium and retaining sodium.
This also reduces the volume of fluid in the blood vessels, the potassium level remains constant and blood pressure falls. Other antihypertensive drugs may also be used to get the hypertension under control.
If Conn’s syndrome is caused by an aldosterone-producing adenoma, doctors remove the tumor in an operation – usually together with the entire affected adrenal gland. This procedure may cure Conn’s syndrome, but at least improves the high blood pressure. Surgery may also be advisable in cases of unilateral hyperplasia of the adrenal cortex. In both cases, the healthy adrenal gland takes over the functions of the removed adrenal gland.
In rare cases, familial hyperaldosteronism type I is the trigger for Conn’s syndrome. In this case, the hormone ACTH ensures that the adrenal cortex produces more aldosterone. Cortisone-like drugs (glucocorticoids) suppress the ACTH effect in type I; in type II, however, they are ineffective.
Course of the disease and prognosis
The course and prognosis of Conn’s syndrome depend on the underlying cause, how well it can be treated and whether it is possible to reduce the blood pressure to a healthy range in the long term. The problem is that Conn’s syndrome often remains undetected if the potassium level is still within the normal range. This is often the case with bilateral adrenal hyperplasia. Correct diagnosis and treatment significantly improve the course and prognosis. Under certain circumstances, Conn’s syndrome can even be cured by surgery.
The biggest problem with Conn’s syndrome is not the disease of the adrenal cortex itself, but the consequential damage resulting from the course of the disease: the risk of cardiovascular diseases such as arteriosclerosis, heart attacks and strokes, as well as eye and kidney damage, increases. Treatment is therefore important for Conn’s syndrome.
Prevention
Conn’s syndrome cannot be prevented, as the causes of the underlying changes to the kidneys are usually unknown.
