Complete Blood Count (CBC): What This Common Blood Test Measures and Why Your Doctor May Order It

A complete blood count, or CBC, is a routine blood test that measures the different cells circulating in your blood, including red blood cells, white blood cells, and platelets, each of which plays an important role in keeping your body healthy.

The amylase test measures the amount of amylase in your blood. Amylase is a digestive enzyme produced mainly by the pancreas and salivary glands that helps break down carbohydrates. This test specifically measures both salivary amylase and total amylase to help identify the source of elevated enzyme levels.

Your doctor may order this test as part of a routine checkup, to help find the cause of symptoms such as fatigue, fever, weakness, or unusual bruising, or to monitor an ongoing condition or how well a treatment is working over time.

Your doctor may order this test if you have symptoms of pancreatic problems, such as severe abdominal pain, nausea, vomiting, or fever. It is commonly used to diagnose acute pancreatitis (inflammation of the pancreas), chronic pancreatitis, pancreatic duct obstruction, and other conditions affecting the pancreas or salivary glands.

A small blood sample is drawn from a vein, usually on the inside of your elbow or the back of your hand. The procedure takes only a few minutes, and most people can return to their normal activities immediately afterward with no special preparation needed.

A healthcare professional will draw a blood sample from a vein in your arm. You may be asked to fast (not eat or drink) for 8-12 hours before the test. The blood sample is then sent to a laboratory for analysis. The test measures the catalytic activity of amylase in your serum or plasma.

Your results report the level of each blood cell type compared with standard reference ranges. Values that are higher or lower than normal may suggest infection, anemia, or other conditions, but your doctor will interpret the full picture together with your symptoms and medical history before making any diagnosis.

Normal amylase levels vary by laboratory, but typically range from 23 to 85 U/L (units per liter). Elevated levels may indicate acute pancreatitis (often 3 or more times the upper limit), chronic pancreatitis, pancreatic cancer, salivary gland infections, kidney disease, or certain medications. Low levels may occur in pancreatic insufficiency or certain liver diseases.

This test is very safe. You may feel a brief sting when the needle is inserted, and some people notice mild bruising or soreness at the puncture site for a day or two. Serious complications are extremely rare, and the benefits of the information gained far outweigh these minor risks.

The risks of having blood drawn are minimal and may include slight pain, bruising, or bleeding at the puncture site. Some people may feel dizzy or lightheaded during or after the blood draw.