Comprehensive Metabolic Panel (CMP)

What Is a Comprehensive Metabolic Panel Test and Why Is It Done?

The comprehensive metabolic panel (CMP) is a blood test that gives doctors information about the body’s fluid balance, levels of minerals like sodium and potassium, and how well the kidneys and liver are working.

Doctors may order a CMP blood test if they’re looking for or keeping track of a condition, or seeing how a medicine or another treatment is working.

Top Things to Know

• The comprehensive metabolic panel (CMP) blood test checks protein, sugar, liver and kidney health, and the balance of fluid and electrolytes.
• Kids might need to stop taking certain medicines or not eat or drink before the blood test.
• Your doctor can explain what it means if any levels are too high or too low.

What Does a Comprehensive Metabolic Panel Check?

A CMP blood test is done to learn about the levels of:

• Glucose, a type of sugar used by the body for energy.
• Certain electrolytes (substances that help keep the body’s fluid and chemical levels in balance), like:
  • Calcium, which plays an important role in how muscles and nerves work.
  • Sodium, potassium, chloride, and carbon dioxide (or bicarbonate), which keep cells in the body working as they should.
  • Blood urea nitrogen (BUN) and creatinine, which are waste products that the kidneys filter out of the blood. The levels of BUN and creatinine show if the kidneys are working the right way.
  • Albumin and total protein, which are needed to build and support muscles, bones, blood, and organ tissue.
• Certain liver proteins called enzymes, which help the liver change food into energy. A CMP test looks at alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST).
• Bilirubin (bil-ih-ROO-ben), a yellow substance that comes from the normal breakdown of red blood cells. The liver changes it so the body can excrete (get rid of) it.

How Are a Comprehensive Metabolic Panel and Basic Metabolic Panel Different?

A basic metabolic panel (BMP) tests blood for some of the things in a CMP: glucose, calcium, sodium, potassium, chloride, carbon dioxide, BUN, and creatinine.

How Can I Help My Child Prepare for a Blood Test?

To help kids get ready for a blood test, find out if they need to fast (not eat or drink) or should stop taking medicines before the test. Explain what to expect during the test. If your child is nervous about it, work together on ways to stay calm. Deep breathing or even imagining being in a peaceful place that makes your child feel safe and calm can help.

What Do Comprehensive Metabolic Panel Test Results Mean?

Lots of things, like exercise, food, and medicine, can cause levels of things measured on a CMP to rise and fall. Here are some other things that the results could mean:

• High glucose levels may point to diabetes.
• If calcium is high, there could be a liver, kidney, or thyroid problem.
• For electrolytes: Sodium levels can be too high or too low in a child who has dehydration (not enough water in the body) from vomiting, diarrhea, or other causes. Potassium levels that are too high or too low can increase the risk of an abnormal heartbeat, or an arrhythmia. Low potassium levels are also linked to muscle weakness and cramps. Chloride levels that aren’t in the “normal” range may be due to things like dehydration, heart disease, or kidney disease. If carbon dioxide levels are too high or too low, there might be a problem with the kidneys or lungs.
• High levels of BUN and creatinine could mean the kidneys aren’t working well. It might also mean kids are dehydrated, have muscle damage, an infection, or a digestive problem.
• Low levels of albumin and total protein might mean there’s a liver, kidney, or diet problem.
• High levels of liver enzymes ALP, ALT, or AST can be a sign that the liver is injured or irritated.
• When bilirubin levels are high, it can mean there’s a problem with the liver, gallbladder (an organ that helps with digestion), bile ducts (tubes that go from the liver to the small intestine to help the body digest food), or that blood cells are breaking down too quickly. Skin might look yellow, a condition called jaundice (JON-diss).

More tests may be needed to find out what’s causing the rise or drop in levels of substances. Your doctor will explain what the results of the CMP test mean for your child. What’s “normal” varies based on things like age and gender.

What Else Should I Know?

If your child needs a CMP, sometimes you might hear it called a complete metabolic panel or a CMP lab test because the results are checked in a lab.

If you have questions about a CMP blood test, talk to your doctor.