A health professional uses a needle to take a blood sample, usually from the arm.

Watch

When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.

There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.

Normal

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

High values

High levels of ammonia in the blood may be caused by:

• Liver disease, such as cirrhosis, Opens dialog or hepatitis, Opens dialog.
• Reye syndrome, Opens dialog.
• Heart failure, Opens dialog.
• Kidney failure, Opens dialog.
• Severe bleeding from the stomach or intestines.

High ammonia values in a baby may be present when the blood types of the baby and the parent who gave birth do not match (hemolytic disease of the newborn, Opens dialog).