What does a Basic Metabolic Panel (BMP) include?

Basic Metabolic Panel (BMP) Components

A Basic Metabolic Panel (BMP) includes eight specific tests that evaluate kidney function, electrolyte balance, acid-base status, and glucose metabolism: glucose, sodium, potassium, chloride, carbon dioxide (CO2), blood urea nitrogen (BUN), creatinine, and calcium. 1

Components of the BMP

The BMP consists of the following eight tests:

1. Glucose: Measures blood sugar levels
2. Electrolytes:
   • Sodium: Essential for fluid balance and nerve/muscle function
   • Potassium: Critical for heart, nerve, and muscle function
   • Chloride: Helps maintain fluid balance and acid-base status
   • Carbon dioxide (CO2): Reflects acid-base balance
3. Kidney Function Tests:
   • Blood Urea Nitrogen (BUN): Waste product filtered by kidneys
   • Creatinine: Waste product that reflects kidney filtration
4. Calcium: Important for bone health, nerve function, and blood clotting

Clinical Significance and Interpretation

Glucose

• Elevated levels may indicate diabetes mellitus, stress response, medication effects, or critical illness
• Low levels may suggest hypoglycemia, which can occur with insulin excess, liver disease, or malnutrition

Electrolytes

• Sodium abnormalities: May indicate hyponatremia or hypernatremia, associated with fluid overload, SIADH, heart failure, liver disease, dehydration, or diabetes insipidus 1
• Potassium abnormalities: Require urgent attention; hypokalemia or hyperkalemia may be associated with diuretic use, vomiting, diarrhea, kidney failure, or medication effects 1
• Chloride and CO2: Help assess acid-base status; low CO2 suggests metabolic acidosis while high CO2 suggests metabolic alkalosis 1

Kidney Function

• BUN and creatinine are used to evaluate kidney function
• Elevated levels may indicate acute or chronic kidney disease
• The KDIGO guidelines recommend calculating estimated Glomerular Filtration Rate (eGFR) from creatinine rather than interpreting creatinine alone 1

Common Pitfalls in BMP Interpretation

1. Relying on creatinine alone: Rather than calculating eGFR for kidney function assessment 1
2. Isolated interpretation: BMP components should be interpreted together, not in isolation 1
3. Overlooking medication effects: Many medications can affect electrolytes and kidney function 1
4. Single measurement focus: Trending values over time provides more clinical insight than a single measurement 1

When to Order a BMP

BMPs are commonly indicated in:

• Initial evaluation of suspected kidney disease
• Hematuria workup
• Diabetes management and monitoring
• Heart failure management 1
• Initial evaluation of new-onset heart failure 1
• Patients with eating disorders 1

BMP vs. Comprehensive Metabolic Panel (CMP)

A BMP includes the eight tests listed above, while a CMP includes these plus:

• Liver function tests (ALT, AST, alkaline phosphatase, total bilirubin)
• Total protein and albumin 2

For patients without clinical variables suggesting liver disease (such as right upper quadrant pain, liver disorders, jaundice, hepatomegaly), limiting testing to a BMP rather than a CMP can provide significant cost savings without compromising care 2.

Follow-up and Monitoring

• For abnormal kidney function (eGFR <60 mL/min/1.73m² or significant albuminuria), repeat testing within 3 months 1
• For electrolyte abnormalities, timing of repeat testing depends on severity; critical values require immediate intervention 1

Remember that BMP results should always be interpreted in the context of the patient's overall clinical presentation, medication regimen, and medical history.