Renin is a protein (enzyme) released by special kidney cells when you have a decreased salt (sodium) level or low blood volume. Most often, the renin blood test is done at the same time as an aldosterone blood test to calculate the renin to aldosterone ratio. If you have high blood pressure, your doctor may order a renin and aldosterone test to help determine the cause of your elevated blood pressure. Test results can help guide your doctor in choosing the correct treatment.

What Abnormal Results Mean
A high level of renin may be due to:

• Adrenal glands that do not make enough hormones (Addison disease or other adrenal gland insufficiency)
• Bleeding (hemorrhage)
• Heart failure
• High blood pressure caused by narrowing of the kidney arteries (renovascular hypertension)
• Liver scarring and poor liver function (cirrhosis)
• Loss of body fluid (dehydration)
• Low salt diet
• Kidney damage that creates nephrotic syndrome
• Kidney tumors that produce renin
• Sudden and very high blood pressure (malignant hypertension)

A low level of renin may be due to:

• Adrenal glands that release too much aldosterone hormone (hyperaldosteronism)
• High blood pressure that is salt-sensitive
• High salt diet
• Treatment with antidiuretic hormone (ADH)
• Treatment with steroid medicines that cause the body to retain salt