A renin assay blood test is done to find the cause of high blood pressure (hypertension). Renin is an enzyme made by special cells in the kidneys. Renin works with aldosterone (a hormone made by the adrenal glands) and several other substances to help balance sodium and potassium levels in the blood and fluid levels in the body, which affects your blood pressure.
A renin test is often done at the same time as an aldosterone test. In some people, it may be normal to have high blood levels of both renin and aldosterone. If renin levels are low and aldosterone levels are high, a tumor may be present in the adrenal glands.
A renin test is done to find the cause of high blood pressure (hypertension), especially when potassium levels in the blood are low.
For 2 to 4 weeks before the test, you may be asked to stop taking medicines that can affect the test, such as diuretics, estrogens, and high blood pressure medicines (especially beta-blockers and ACE inhibitors). Your doctor may have you take other medicines for a few weeks that will not change the renin test results.
Do not eat natural black licorice for 2 weeks before the test. Do not eat or drink foods that contain caffeine the day before the test. Natural licorice and caffeine can change the test results.
For 3 days before a renin test, you may be asked to follow a special low-sodium diet.
You may be asked to not eat or drink anything for 8 hours before the test.
You may need to sit or lie down to relax for 1 to 2 hours before your blood is collected. A second blood sample may be collected after you move around for 2 hours.
The health professional drawing blood will:
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having blood sample taken from a vein.
A renin assay blood test is done to find the cause of high blood pressure (hypertension). The time of day and your position (standing, sitting, or lying down) before the blood sample is collected, your age, and the level of sodium in your blood all affect the test results.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
|Adult (upright position, normal-sodium diet)|
|Adult (lying down, normal-sodium diet)||
0.2–1.6 ng/mL/hr or 0.2–1.6 mcg/L/hr
|Adult (upright position, low-sodium diet)||
4.2–19.8 ng/mL/hr or 4.2–19.8 mcg/L/hr
|Adult (lying down, low-sodium diet)||
0.4–3.2 ng/mL/hr or 0.4–3.2 mcg/L/hr
Many factors can affect renin test results. Your doctor will talk with you about any abnormal results that may be related to your symptoms and medical history.
A low renin value can mean Conn's syndrome is present.
Reasons you may not be able to have the test or why the results may not be helpful include:
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- 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.
|Primary Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Specialist Medical Reviewer||Alan C. Dalkin, MD - Endocrinology|
|Last Revised||July 9, 2010|
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