Conn’s syndrome:
What is Conn’s syndrome?
Conn’s syndrome also known as Primary Hyperaldosteronism, is a tumor of adrenal glad which causes excess production of a hormone called aldosterone. The major function of aldosterone is to reabsorb sodium and excrete potassium and acid (H+). Conn’s syndrome can be either a unilateral tumor (located on only one adrenal glad) which are also the most common adrenal tumors or bilateral tumor (located on both adrenal glands). The reason Conn’s syndrome is important is because of the fact that it is potentially curable cause of high blood pressure (hypertension).
Are there any other causes of Hyperaldosteronism?
Yes, other than Conn’s syndrome which is a primary cause of Hyperaldosteronism we also have “Secondary” causes of Hyperaldosteronism which present very similar to Conn’s syndrome “primary hyperaldosteronism”.
The secondary causes of hyperaldoteronism are not due to tumors but rather, due to other manifestations that reduces the amount of blood that reaches the kidneys. Our kidney is a one of the main organs of our body which also has a huge part in maintaining the blood pressure. Kidneys maintain blood pressure through Juxtaglomerular apparatus (JGA) which includes:
- Juxtaglomerular cells (JG cells) which are modified smooth muscle of Afferent arterioles,
- Macula densa which are sodium sensors that are part of the distal convoluted tubules.
Juxtaglomerular cells secrete renin in response to decrease renal blood pressure, therefor activating the Renin Angiotensin Aldosterone System (RAAS) by secreting Renin. It is important to know that Renin also increases the sympathetic tone (β1) activity of the heart leading to increase cardiac output.
What are some of the causes of Secondary hyperaldosteronism?
- Renal artery stenosis: This causes the kidney to assume there is hypotension throughout the body since not enough blood is reaching the kidney due to vasoconstriction of the afferent arterioles. Therefore the kidney will assume there is low blood pressure and it starts secreting renin which activates the Renin Angiotensin Aldosterone System, leading to increase aldosterone production.
- Congestive heart failure: Since the heart is failing to pump out blood, no enough blood will reach different organs in our body, especially the kidneys. Therefore the kidney will again assume there is low blood pressure and it starts secreting renin which activates the Renin Angiotensin Aldosterone System, leading to increase aldosterone production.
- Liver Cirrhosis: causes decreased protein production especially albumin. Decreased amount of protein in the serum leads to decreased Colloid osmotic pressure, which will lead to intravascular volume depletion. This makes the kidney think that there is low blood pressure, and there fore it starts secreting renin which activates the Renin Angiotensin Aldosterone System, leading to increase aldosterone production.
- Nephrotic syndrome: Like liver cirrhosis, nephrotic syndrome leads to decreased serum protein concentration, but in the case of nephrotic syndromes it is due to loss of protein and not protein production. Decreased amount of protein in the serum leads to decreased Colloid osmotic pressure, which will lead to intravascular volume depletion. This makes the kidney think that there is low blood pressure, and there fore it starts secreting renin which activates the Renin Angiotensin Aldosterone System, leading to increase aldosterone production.
What are the laboratory values of Conn’s syndrome?
The laboratory values for both Conn’s syndrome (primary hyperaldosteronism) and Secondary Hyperaldosteronism are exactly the same,
- Hypertension
- Hypernatremia
- Hypokalemia
- Metabolic alkalosis
How to differentiate between Conn’s syndrome (primary hyperaldosteronism) and Secondary Hyperaldosteronism?
- Best initial test –> Measure the ratio of plasma aldosterone to plasma renin. An elevated plasma renin excludes Conn’s syndrome (primary hyperaldosteronism).
Conn’s syndrome (Primary Hyperaldosteronism) v.s. Secondary – Medical Institution
- Most accurate test to confirm the presence of a unilateral adenoma –> is sample of the venous blood draining the adrenal. It will show a high aldosterone level.
- CT scan of the adrenals –> Should only be done after biochemical testing confirms:
- Low potassium
- High aldosterone despite a high-salt diet
- Low plasma renin level
How to treat Hyperaldosteronism?
- Laparoscopy: for removal of a unilateral tumors.
- Spironolactone or Eplerenone: for treatment of Bilateral tumors or Secondary hyperaldosteronism.