A renin test is often done at the same time as
an aldosterone test. For more information, see the medical test
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 an enzyme 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. However, in some situations (such as pregnancy), PRA results may be more
accurate than the renin direct immunoassay.
If a kidney artery is
blocked, another test, such as a captopril test, may be done. For the captopril
test, you will take a dose of captopril after the renin assay test is done and
your blood pressure is measured. Follow-up blood pressure measurements and a
PRA test are done 60 minutes later to find high blood pressure. Other tests
that may also be done are
duplex Doppler ultrasound or
arteriography. For more information, see the medical
Doppler Ultrasound and
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.