Complete Blood Count (CBC)

The complete blood count (CBC) is a common blood test that measures the different cells in your blood, including red blood cells, white blood cells, and platelets. It gives your healthcare provider a broad picture of your overall health and can help detect a wide range of conditions, from anemia and infections to blood disorders.

The Angiotensin I test measures the amount of Angiotensin I in your blood plasma. Angiotensin I is a protein hormone (peptide) that plays a key role in the renin-angiotensin-aldosterone system (RAAS), which helps control your blood pressure and the balance of fluids and salts in your body.

Your doctor may order this test as part of a routine checkup, to help find the cause of symptoms such as fatigue, weakness, fever, or unusual bruising, or to monitor a condition you already have, such as anemia, infection, or the effects of certain medications on your blood cells.

Your doctor may order this test to help diagnose or monitor conditions such as: high blood pressure (hypertension), kidney problems, heart failure, and certain hormonal disorders. It may also be used to evaluate the cause of low blood pressure or to investigate adrenal gland function.

The test is done by drawing a small sample of blood from a vein, usually on the inside of your elbow or the back of your hand. A healthcare professional will clean the site, wrap a band around your upper arm, insert a thin needle, and collect the blood into a tube. The sample is then sent to a laboratory for analysis, and the whole process usually takes just a few minutes.

A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The blood is collected into a special tube containing an enzyme inhibitor to prevent the breakdown of Angiotensin I. You may feel a brief sting or mild discomfort when the needle is inserted. The sample is then sent to a laboratory for analysis.

In most cases, no special preparation is needed, and you can eat and drink normally before the test. However, tell your doctor about all medicines, vitamins, or supplements you take, because some can affect the results. If the CBC is being done together with other tests that require fasting, your doctor will give you specific instructions to follow beforehand.

Your doctor may ask you to stop taking certain medications before the test, as some drugs can affect Angiotensin I levels. These may include blood pressure medications (especially ACE inhibitors, ARBs, and diuretics), hormone medications, and some pain relievers. Follow your doctor's instructions carefully. You may need to fast (not eat or drink) for a certain period before the test.