Hypokaliaemia leads to high blood pressure

Primary hyperaldosteronism (Conn syndrome) is a disease of the adrenal glands in which the hormone aldosterone is overproduced. Aldosterone is formed in the outermost layer (zona glomerulosa) of the adrenal cortex and plays a key role in regulating the body's water and salt balance. Due to the effect on the salt transport in the kidneys, it leads to the excretion of potassium and the reabsorption of sodium and water.

frequency

While it has previously been assumed that primary hyperaldosteronism is the cause of hypertension in less than 1% of patients with high blood pressure, it is now assumed that the disease one of the most common causes of what is known as secondary hypertension represents. The information on the frequency of primary hyperaldosteronism depends on the population examined and ranges from 4-12% in specialized high-pressure outpatient departments up to 32% in patients with severe hypertension or hypertension that cannot be controlled by medication. The proportion is even higher in patients with high blood pressure and low potassium levels in the blood (hypokalaemia). In contrast, Conn's syndrome is significantly less common in unselected patients with high blood pressure.

complaints

The Guiding symptoms of Conn's syndrome are:

  • high blood pressure that is difficult to control (despite three or more blood pressure medication)
  • Decrease in blood potassium levels

The symptoms of patients usually do not differ from those with "normal" (essential) high blood pressure. However, the risk of secondary diseases such as heart attack, stroke, or kidney damage is significantly higher for patients with Conn's syndrome.

Diagnosis

The following patient groups should be examined for the presence of primary hyperaldosteronism:

  • Severe or therapy-resistant hypertension
  • Hypertension + spontaneous or diuretic-induced hypokalaemia
  • Patients with first-degree relatives with primary aldosteronism or a positive family history of early onset hypertension (<40 years of age)
  • Accidentally discovered adrenal gland tumor (incidentaloma) + hypertension

A blood test to determine the aldosterone-renin quotient is used as a screening test. Since many blood pressure medication can lead to a falsification of this test, it is often necessary to change the medication treatment beforehand. In the event of a conspicuous laboratory finding, a confirmation test (e.g. a salt exposure test) is then required. If this test is also abnormal, the diagnosis of primary hyperaldosteronism is confirmed.

The main causes of Conn syndrome are these Aldosterone-producing adenoma (Conn adenoma) and the bilateral adrenal hyperplasia, i.e. a microscopic enlargement of both adrenal glands, both of which are almost 50% of the cases. In order to be able to reliably differentiate the source of the increased aldosterone production, it is recommended, in addition to thin-layer computed tomography (CT) or magnetic resonance imaging (MRT), to take blood separately from the adrenal blood vessels directly from the adrenal blood vessels (so-called adrenal vein catheterization).

therapy

In these patients, the adrenal gland is usually affected minimally invasive surgery removed, whereby the disease can be cured or at least the high blood pressure can be improved.

Surgical specimen of Conn's adenoma after laparoscopic surgery
(Image material: Prof. T. Mussack, University of Munich Clinic)

In these cases, patients receive a lifetime medical therapy with the aldosterone antagonist spironolactone, which counteracts the effects of the excessive hormone aldosterone formed in this disease at the receptor level. If this is not sufficient for a good blood pressure control, additional antihypertensive drugs can be given.

Helpful internet addresses:

 

Authors:
Prof. Dr. F. Beuschlein,
PD Dr. S. Diederich,
PD Dr. M. Fassnacht,
PD Dr. M. Quinkler,
PD Dr. F. Riepe,
PD Dr. H. Willenberg
for the Advisory Board of the Adrenal Glands, Steroids and Hypertension Section