A comprehensive metabolic panel is a group of blood tests. They provide an overall picture of your body's chemical balance and metabolism. Metabolism refers to all the physical and chemical processes in the body that use energy. Show
Alternative NamesMetabolic panel - comprehensive; CMP How the Test is PerformedAblood sampleis needed. How to Prepare for the TestYou should not eat or drink for 8 hours before the test. How the Test will FeelWhen the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away. Why the Test is PerformedThis test gives your health care provider information about:
Your provider may order this test to check you for side effects of medicines or diabetes, or for liver or kidney disease. Normal ResultsNormal values for the panel tests are:
Normal values for creatinine can vary with age. Normal value ranges for all tests may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your provider about the meaning of your specific test results. What Abnormal Results MeanAbnormal results can be due to a variety of different medical conditions. These may include kidney failure, liver disease, breathing problems, and diabetes or diabetes complications. RisksThere is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others. Other risks associated with having blood drawn are slight but may include:
ReferencesChernecky CC, Berger BJ. Comprehensive metabolic panel (CMP) - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:372. McPherson RA, Pincus MR. Disease/organ panels. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:appendix 7. The type of fasting required for blood work is different from the "NPO after midnight" order that healthcare providers give the day before procedures. "NPO after midnight" means "nil per os," which is Latin for "nothing by mouth." NPO means no food or beverages, not even water. This is ordered before procedures that require sedation or anesthesia, since the medications used can cause nausea and vomiting, increasing your risk of choking or aspiration (when food enters your airways or lungs accidentally). General Rules for FastingTo fast for blood work, do not eat anything for eight to 12 hours before the test. You may drink water, tea, or black coffee (no sugar or milk added). It's best to schedule fasting blood work for the morning, so that you don't have to spend the whole day hungry. How Long to FastGenerally, you should fast for eight to 12 hours before lab work that requires it. Fasting for a blood sugar test, which is included in the basic metabolic panel, is generally eight to 12 hours. You can always clarify how long to fast with your healthcare provider. If you are unsure, aim for 12 hours of fasting. For example, if you schedule your test for first thing in the morning, you should generally not eat anything after dinnertime the night before. DrinkingDrinking certain liquids is allowed, and even encouraged, before blood work. This is because a 12-hour fast from drinking fluids can make you slightly dehydrated. This causes your veins to flatten and makes them harder to find for a venipuncture. Drinking should be limited to water, tea, or black coffee with no sweeteners or creams. Drinking water is recommended before lab tests so that you do not become dehydrated. The phlebotomist (medical professional who performs blood draws) will have an easier time drawing your blood if you are well-hydrated. EatingEating before certain blood work can affect results. Specifically, eating before a cholesterol panel can raise the triglyceride levels and potentially the LDL (low-density lipoprotein) levels (known as "bad" cholesterol). Individuals who are not on statin medications for cholesterol may not be required to fast, and new guidelines suggest that fasting before a lipid test is optional. Eating before a blood glucose test will raise your blood sugar. However, another test for diabetes, called the hemoglobin A1c test, does not require fasting, since it looks at a marker of blood sugar control over the past few months rather than directly measuring blood sugar. Less common tests that require fasting include:
Medication and Blood TestsEven if you are asked to fast for blood work, you should take your prescribed medications with water, unless specifically requested not to do so. The exception to this is vitamins and supplements. These may affect certain lab tests, so they should be held the morning of a lab test. Discuss what medications you are taking with your healthcare provider and clarify ahead of time if you have any questions on holding medications before blood work. Pregnancy and Blood TestsMost lab tests drawn in pregnancy do not require fasting, with the exception of the glucose challenge test. This test is performed to screen for a condition called gestational diabetes. For this test, you will be asked to consume a special sugary beverage that contains a specific amount of glucose. Your blood glucose level will be tested at specific time intervals. What to Do If You Accidentally Eat or DrinkIf you accidentally ate or drank a sweetened beverage before your test, let your healthcare provider know. Depending on what the test was ordered for, you may be able to go ahead and have your blood drawn, and your healthcare provider will interpret it accordingly. For example, if you are having a screening cholesterol panel and you ate breakfast before the test, it's not necessary to reschedule it. In fact, newer recommendations from the National Lipidology Association state that fasting for a screening lipid panel is optional. While your breakfast will affect the triglyceride level, other important parts of the test, such as the total cholesterol and HDL (high-density lipoprotein, known as "good" cholesterol) will not be affected. LDL will only be affected if the triglyceride level is very elevated. If the triglyceride level is elevated, you may be asked to come back to repeat the test. On the other hand, if a test was ordered specifically for blood sugar and you ate breakfast, the test may not be useful. Pregnant patients undergoing the glucose challenge test will be asked to fast. If they do not, the test will be rescheduled. SummaryMany lab tests do not require fasting. But for those that do, such as blood glucose tests, eating food can affect the results. Check with the healthcare provider who ordered the blood work to see if fasting is necessary, and if so, do not eat for to eight to 12 hours before the test. It's fine to take your prescribed medication and drink water before the test to stay hydrated. A Word From VerywellBlood tests can be a crucial part of monitoring health, and it's important that they be as accurate as possible. Make sure to confirm with your healthcare provider whether or not you are required to fast before your blood test. Remember that it's still important to stay hydrated by drinking water and to take your medications as prescribed. Frequently Asked Questions
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