Many things can affect renin test results. Your
doctor will talk with you about any abnormal results that may be related to
your symptoms and past health.
A high renin value can mean kidney
disease, blockage of an artery leading to a kidney,
cirrhosis, excessive bleeding (hemorrhage), or
malignant high blood pressure is present.
A low renin value can mean
some types of kidney disease or Conn's syndrome is present.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- Eating natural black licorice in the 2 weeks
before the test.
- Taking some medicines used to treat high blood
- Taking aspirin, caffeine,
- Your position (standing,
sitting, or lying down) before the test is done or the time of day when the
blood sample is drawn, as well as recent salt intake.
- Taking very
high doses of
- Being pregnant.
What To Think About
- A renin test is often done at the same time as
an aldosterone test. To learn more, see the topic
- A renin stimulation test may
occasionally be done if blood renin levels are low. To prepare for this test,
you will eat a low-sodium diet for 3 days. A blood renin level will be drawn
and a diuretic, usually furosemide (Lasix), will be put in a vein (intravenous)
in your arm. Normally, blood renin levels will increase, but in Conn's syndrome
blood renin levels will not change after taking the diuretic.
hospitals now measure renin activity with the renin direct immunoassay, which
measures the amount of renin in the blood. A plasma renin activity (PRA) test
measures the production of a hormone called angiotensin I rather than renin itself. A renin
direct immunoassay is easier to do and can generally be done instead of the PRA
test. But in some situations (such as pregnancy), PRA results may be more
accurate than the renin direct immunoassay.
- Other tests
that may be done to investigate high blood pressure include
duplex Doppler ultrasound,
arteriography, magnetic resonance imaging (MRI), and magnetic resonance angiography (MRA).