From the Guidelines
You should not test PRA while on an ACE inhibitor, as the results may be falsely elevated, and it is recommended to withhold ACE inhibitors for 2 to 5 days before the test to reduce the possibility of a false negative result. According to the American College of Cardiology position statement 1, angiotensin-converting enzyme inhibitors are best withheld for 2 to 5 days before the test to ensure accurate results. When considering testing PRA, it is essential to understand that ACE inhibitors disrupt the negative feedback loop that normally suppresses renin production, causing PRA levels to increase. Some key points to consider when testing PRA include:
- Withholding ACE inhibitors for 2 to 5 days before the test to reduce the possibility of a false negative result 1
- Administering other antihypertensive drugs as usual, while ensuring the patient is adequately hydrated, particularly if diuretics are being administered 1
- Monitoring blood pressure frequently during the test 1
- Considering alternative tests, such as radionuclide scintirenography, which may be performed with or without ACE inhibitors 1
From the FDA Drug Label
Removal of angiotensin II negative feedback on renin secretion leads to increased plasma renin activity.
The answer to whether you can test PRA (Plasma Renin Activity) while on an ACE inhibitor is yes, but with caution. ACE inhibitors can increase plasma renin activity by removing the negative feedback of angiotensin II on renin secretion. However, the test results may be affected by the ACE inhibitor therapy.
- Key points:
From the Research
Testing PRA while on ACE Inhibitor
- The effects of ACE inhibitors on plasma renin activity (PRA) have been studied in various contexts 4, 5, 6.
- ACE inhibitors, such as lisinopril, have been shown to increase PRA by inhibiting the conversion of angiotensin I to angiotensin II, which in turn stimulates the release of renin 4, 5.
- However, the increase in PRA may be blunted by beta-adrenergic blockade, as shown in a study where propranolol was administered in combination with lisinopril or enalapril 5.
- In patients with primary aldosteronism, ACE inhibitors can cause false-negative results in the aldosterone/renin ratio (ARR) test, but the aldosterone/equilibrium angiotensin II ratio (AA2R) may be a more reliable alternative 7.
- The effects of ACE inhibitors on PRA can vary depending on the specific drug, dose, and population being studied, as demonstrated by a study comparing the effects of lisinopril and enalapril on PRA in healthy volunteers 5.
- In diabetic rats, lisinopril has been shown to increase PRA at lower doses, but decrease it at higher doses 6.
Considerations for Testing PRA
- When testing PRA in patients on ACE inhibitors, it is essential to consider the potential effects of the drug on the renin-angiotensin-aldosterone system and the timing of the test in relation to the dose of the ACE inhibitor 4, 5, 6.
- The choice of test, such as the ARR or AA2R, may also be important in patients on ACE inhibitors, as some tests may be more reliable than others in this context 7.