A comprehensive metabolic panel, or CMP, is a blood test that measures 14 different substances in your blood to give a broad snapshot of how your body is functioning. It checks your blood sugar, electrolyte balance, kidney health, liver health, and protein levels, all from a single blood draw. Doctors order it routinely during annual physicals, but it’s also used to monitor chronic conditions like diabetes, high blood pressure, and liver or kidney disease.
What the 14 Tests Measure
The CMP covers four general areas of your health, each represented by a cluster of individual markers:
- Blood sugar: Glucose
- Electrolytes: Sodium, potassium, chloride, and bicarbonate (sometimes listed as CO2)
- Kidney markers: Blood urea nitrogen (BUN) and creatinine
- Liver markers: ALP, ALT, AST, and bilirubin
- Proteins: Albumin and total protein
- Mineral: Calcium
None of these markers is diagnostic on its own. Your doctor looks at patterns across the panel. For example, if both BUN and creatinine are elevated, that points more strongly toward a kidney issue than either number alone would.
How a CMP Differs From a BMP
A basic metabolic panel (BMP) includes 8 of the 14 CMP tests: glucose, calcium, and the four electrolytes plus the two kidney markers. The CMP adds six more, all related to liver function and protein levels: ALP, ALT, AST, bilirubin, albumin, and total protein. If your doctor only needs to check your blood sugar, electrolytes, and kidneys, a BMP is sufficient. A CMP is ordered when liver health or protein status also needs evaluation.
What the Kidney Markers Tell You
Creatinine is a waste product generated by normal muscle activity. Healthy kidneys filter it out and send it into your urine, so when creatinine builds up in the blood, it suggests your kidneys aren’t filtering efficiently. The normal range is 0.6 to 1.3 mg/dL.
BUN works similarly. It comes from the breakdown of protein in the food you eat. Nitrogen from that protein normally binds to other waste products, gets filtered by the kidneys, and leaves your body through urine. A normal BUN level falls between 6 and 20 mg/dL. When it’s elevated alongside creatinine, kidney dysfunction is a likely explanation. When BUN rises on its own, dehydration or a high-protein diet may be responsible.
Doctors often use your creatinine result to calculate an estimated glomerular filtration rate (eGFR), which adjusts for your age and sex to give a more accurate picture of kidney function than creatinine alone. You may see eGFR reported alongside your CMP results even though it isn’t one of the 14 measured values.
What the Liver Markers Tell You
Three enzymes in the CMP reflect liver health. ALT is found almost exclusively in liver cells, making it the most specific indicator of liver damage. Its normal range is 4 to 36 U/L. AST is present in the liver but also in the heart, muscles, and other tissues, so an elevated AST (normal: 8 to 33 U/L) can point to problems beyond the liver. ALP is found in the liver and bones, with a normal range of 20 to 130 U/L. High ALP can signal a blocked bile duct, gallbladder inflammation, or bone disorders like Paget’s disease.
Bilirubin is a yellowish waste product created when your body breaks down old red blood cells. The liver processes bilirubin so it can be excreted. Normal levels are 0.1 to 1.2 mg/dL. Elevated bilirubin can indicate liver disease, bile duct blockage, or unusually rapid red blood cell destruction. Very high levels cause jaundice, the visible yellowing of skin and eyes.
Electrolytes and Fluid Balance
The four electrolytes in a CMP regulate some of the most basic functions in your body. Sodium (normal: 135 to 145 mEq/L) controls how much fluid your body retains and helps nerves and muscles work properly. Potassium (3.7 to 5.2 mEq/L) is critical for heart rhythm and muscle contractions. Chloride (96 to 106 mEq/L) works alongside sodium to maintain blood volume and blood pressure. Bicarbonate (23 to 29 mEq/L) keeps your blood’s pH in a safe range and plays a key role in transporting carbon dioxide through the bloodstream.
Electrolyte imbalances can result from dehydration, vomiting, diarrhea, kidney disease, or certain medications like diuretics. Even modest shifts in potassium or sodium can cause fatigue, muscle cramps, or irregular heartbeat, which is why these values appear on routine bloodwork so frequently.
Glucose, Proteins, and Calcium
The glucose reading on a CMP is a fasting blood sugar measurement. A normal result is 70 to 100 mg/dL. Values between 100 and 125 mg/dL suggest prediabetes, while 126 mg/dL or higher on two separate tests indicates diabetes.
Total protein (normal: 6.0 to 8.3 g/dL) and albumin (3.4 to 5.4 g/dL) reflect your nutritional status and liver function, since the liver produces most blood proteins. Low levels of either can point to liver disease, kidney disease, or malnutrition. Conditions that impair nutrient absorption, like celiac disease or Crohn’s disease, can also drive protein levels down. Unusually high total protein sometimes signals chronic infection or, less commonly, blood cancers like multiple myeloma.
Calcium (8.5 to 10.2 mg/dL) is involved in bone health, nerve signaling, and muscle function. Abnormal calcium levels can reflect parathyroid disorders, vitamin D deficiency, kidney disease, or certain cancers.
How to Prepare
You’ll typically need to fast for 8 hours before a CMP. Water is usually fine, but food and other beverages can affect glucose and other results. If you’re unsure whether your doctor wants you fasting, call ahead. The blood draw itself takes just a few minutes, and results are usually available within one to two business days.
What Can Affect Your Results
Several factors beyond your actual health can shift CMP values. Dehydration concentrates your blood and can falsely elevate BUN, sodium, and other markers. Certain antibiotics can interfere with creatinine measurement, producing readings that look higher than your true level. High-dose vitamin C supplements can cause glucose meters to report falsely elevated blood sugar. If you’re taking any medications or supplements regularly, mention them when your results are reviewed so your doctor can factor in possible interference.
Cost Without Insurance
If you’re paying out of pocket, a CMP typically costs between $40 and $55 at major commercial labs. Quest Health, for example, lists the panel at about $44 plus a $6 physician service fee. With insurance, the CMP is almost always covered as part of routine preventive care at no additional cost to you.