Sodium chloride (NaCl) loading test

Hyperaldosteronism diagnosis with a salt loading test (NaCl challenge test).

The sodium chloride loading test is a specialized diagnostic method used to assess blood aldosterone levels and identify potential hormonal regulation disorders that may contribute to elevated blood pressure and electrolyte imbalances—particularly in potassium and sodium levels.

This test is especially important in the diagnosis of primary hyperaldosteronism, an endocrine disorder in which the adrenal glands produce excessive amounts of aldosterone regardless of the body’s actual needs. This condition, also known as Conn’s syndrome, is one of the most common causes of secondary hypertension and is often underdiagnosed.

How is the Sodium Chloride Loading Test Performed?

During the procedure, the patient is administered 0.9% sodium chloride (normal saline) intravenously in a controlled volume and over a specified period of time. This salt loading is expected to physiologically suppress aldosterone secretion. If aldosterone levels remain elevated after the loading, it may indicate primary hyperaldosteronism.

The entire test is conducted under medical supervision, ensuring patient safety and enabling prompt management of any potential side effects. Simultaneous blood tests are performed to accurately monitor hormone level changes, allowing for a precise interpretation and a definitive diagnosis.

When is this test recommended?

• Chronic elevated blood pressure
• Low blood potassium levels (hypokalemia)
• Suspected endocrine (hormonal) disorders
• To guide the selection of a more effective hypertension treatment strategy
• To confirm or rule out adrenal gland pathologies

The sodium chloride loading test is a crucial step toward achieving an accurate diagnosis and targeted therapy for patients with suspected hormone-related hypertension. Timely diagnosis helps prevent complications and significantly improves quality of life.