Plasma Renin Activity (PRA) Test
Plasma Renin Activity (PRA) Test
The Plasma Renin Activity (PRA) Test is a blood test used to measure the activity of renin, an enzyme secreted by the kidneys that plays a crucial role in the renin-angiotensin-aldosterone system (RAAS). This system helps regulate blood pressure, electrolyte balance, and fluid homeostasis.
Renin stimulates the production of angiotensin I, which is converted into angiotensin II, a potent vasoconstrictor that increases blood pressure and triggers the release of aldosterone, a hormone that regulates sodium and potassium levels.
This test is useful in evaluating hypertension (high blood pressure), adrenal gland disorders, and electrolyte imbalances
What is the Plasma Renin Activity (PRA) Test Used For?
- Diagnosing primary hyperaldosteronism (Conn’s syndrome)
- Evaluating secondary hypertension caused by kidney dysfunction
- Assessing adrenal insufficiency
- Investigating fluid and electrolyte imbalances
Symptoms Indicating the Need for a PRA Test
Resistant hypertension (uncontrolled high blood pressure despite medication)
Low potassium levels (hypokalemia)
Excessive thirst and frequent urination
Fatigue and muscle weakness
Dizziness or episodes of fainting
Preparation for Test
Fasting may be required; follow your doctor’s instructions. Avoid excessive salt intake prior to the test. Certain blood pressure medications (such as ACE inhibitors, beta-blockers, and diuretics) may need to be stopped before the test. The blood sample is drawn while the patient is seated or lying down, depending on the clinical indication
Interpretation of Test Results
High Renin Levels: May indicate secondary hypertension due to renal artery stenosis or chronic kidney disease. It can be associated with low blood volume (hypovolemia).
Low Renin Levels: Suggests primary hyperaldosteronism (Conn’s syndrome), especially when paired with high aldosterone levels. It may indicate adrenal insufficiency or excessive sodium intake
FAQs
Who should get this test?
Individuals with uncontrolled high blood pressure, suspected adrenal disorders, or unexplained electrolyte imbalances
How is this test performed?
A blood sample is drawn from a vein and analyzed in a laboratory
Can medications affect test results?
Yes, certain blood pressure medications, diuretics, and steroid treatments can influence renin levels
What conditions can this test help diagnose?
It helps detect hyperaldosteronism, kidney disease, and secondary hypertension
What happens if results are abnormal?
Your doctor may recommend further tests, imaging studies, or lifestyle changes based on the findings.
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