Components of a Comprehensive Metabolic Panel (CMP)
A Comprehensive Metabolic Panel (CMP) includes 14 specific blood tests that evaluate kidney function, liver function, electrolyte and fluid balance, and blood sugar levels. 1, 2
Core Components of a CMP
Electrolytes
- Sodium
- Potassium
- Chloride
- Carbon dioxide (bicarbonate)
Kidney Function Tests
- Blood Urea Nitrogen (BUN)
- Creatinine
- Estimated Glomerular Filtration Rate (eGFR) - calculated from creatinine
Liver Function Tests
- Alanine aminotransferase (ALT)
- Aspartate aminotransferase (AST)
- Alkaline phosphatase
- Total bilirubin
- Total protein
- Albumin
Glucose Metabolism
- Glucose (blood sugar)
Clinical Utility of CMP
The CMP provides critical information about:
Kidney function: BUN, creatinine, and eGFR help assess how well the kidneys are filtering waste products 1, 2
Liver function: ALT, AST, alkaline phosphatase, bilirubin, albumin, and total protein evaluate liver health and function 1
Electrolyte balance: Sodium, potassium, chloride, and carbon dioxide measurements help assess fluid and electrolyte status 1
Metabolic status: Glucose levels provide information about carbohydrate metabolism 3
Acid-base balance: Carbon dioxide (bicarbonate) levels help evaluate acid-base status 2
When CMP is Ordered
A CMP is commonly ordered:
- As part of a routine health examination
- When evaluating specific organ systems, particularly kidney and liver
- For monitoring chronic conditions like diabetes, kidney disease, or liver disease
- Before starting certain medications that may affect kidney or liver function
- During hospitalization to monitor electrolyte balance and organ function 1
Differences Between CMP and BMP
A Basic Metabolic Panel (BMP) contains 8 tests, while a CMP contains 14 tests. The main difference is that a CMP includes liver function tests that are not part of a BMP 4, 5:
- BMP includes: glucose, calcium, sodium, potassium, chloride, carbon dioxide, BUN, and creatinine
- CMP includes all BMP components plus liver function tests (ALT, AST, alkaline phosphatase, bilirubin, total protein, and albumin)
Clinical Considerations
- Fasting is typically recommended before a CMP to ensure accurate glucose and lipid measurements 2
- Results should be interpreted in the context of the patient's clinical condition and other laboratory findings
- Abnormal values may require follow-up testing for confirmation 6
- Point-of-care CMP testing can reduce emergency department length of stay compared to central laboratory testing 7
Quality Considerations
- Clinical laboratories should calibrate serum creatinine assays using international standards to ensure accuracy 2
- Enzymatic creatinine assays are preferred over Jaffe assays in certain populations (e.g., children) due to higher accuracy 2
- eGFR calculations should use validated prediction equations such as MDRD or CKD-EPI 2
A CMP provides comprehensive information about a patient's metabolic status and is an essential tool for evaluating overall health, diagnosing diseases, and monitoring treatment effects.