Definitions

Primary aldosteronism

Primary aldosteronism

Primary aldosteronism, also known as primary hyperaldosteronism and Conn syndrome, is characterized by the overproduction of the mineralocorticoid hormone aldosterone by the adrenal glands. Aldosterone causes increase in sodium and water retention and potassium excretion in the kidneys, leading to arterial hypertension (high blood pressure). Also increase production of mineralocorticoid from the adrenal gland is evident. It is a rare but recognised cause of hypertension.

Signs, symptoms and findings

Primary hyperaldosteronism, aside from high blood pressure, may manifest with muscle cramps (due to hyperexcitability of neurons), muscle weakness (due to hypoexcitability of skeletal muscles), headaches (due to the low potassium), and metabolic alkalosis (due to increased secretion of H+ ions by the kidney). The high pH of the blood makes calcium less available to the tissues and causes symptoms of hypocalcemia (low calcium levels).

It can be mimicked by liquorice ingestion (glycyrrhizin) and Liddle syndrome.

Diagnosis

Measuring aldosterone alone is not considered adequate to diagnose primary hyperaldosteronism. Rather, both renin and aldosterone are measured, and the ratio is diagnostic.

Usually, renin levels are suppressed, leading to a very low renin-aldosterone ratio (<0.0005). This test is confounded by antihypertensive drugs, which have to be stopped up to 6 weeks.

If plasma levels of renin and aldosterone suggest hyperaldosteronism, CT scanning can confirm the presence of an adrenal adenoma. If the clinical presentation primarily involves hypertension and elevated levels of catecholamines, CT or MRI scanning can confirm a tumor on the adrenal medulla, typically a pheochromocytoma.

Causes

The syndrome is due to:

Therapy

The treatment for hyperaldosteronism depends on the underlying cause. In patients with a single benign tumor (adenoma), surgical removal (adrenalectomy) is curative. This is usually performed laparoscopically, through several very small incisions. For patients with hyperplasia of both glands, successful treatment is often achieved with spironolactone or eplerenone, drugs that block the effect of aldosterone. In males, one common side effect of the lower-cost spironolactone drug therapy sometimes seen is gynecomastia. Fortunately, gynecomastia usually does not occur with the slightly more costly eplerenone drug therapy.

In the absence of proper treatment, individuals with hyperaldosteronism often suffer from poorly controlled high blood pressure, which may be associated with increased rates of stroke, heart disease, and kidney failure. With appropriate treatment, the prognosis is excellent.

Eponym

It is named after Dr Jerome W. Conn (1907-1994), the American endocrinologist who first described the condition at the University of Michigan in 1955.

References

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