What Does a Basic Metabolic Panel (BMP) Measure?
A Basic Metabolic Panel (BMP) measures seven essential blood components: sodium, potassium, chloride, bicarbonate (CO2), glucose, blood urea nitrogen (BUN), and creatinine. 1
Core Components of the BMP
The BMP provides critical information across multiple physiological systems:
Electrolytes
- Sodium, potassium, and chloride assess fluid balance, cellular function, and acid-base homeostasis 1, 2
- These electrolytes directly reflect and impact renal function 2
Kidney Function Markers
- Blood urea nitrogen (BUN) and creatinine evaluate renal filtration capacity and kidney health 1, 2
- These values must be interpreted together because they both reflect renal function and impact acid-base balance 2
Acid-Base Status
- Bicarbonate (CO2) indicates metabolic acid-base balance 1
- Low bicarbonate in dialysis patients almost always indicates metabolic acidosis and should be maintained at or above 22 mmol/L 1
Glucose Metabolism
- Glucose screens for diabetes and insulin resistance 1
- Fasting blood glucose or HbA1c is the most appropriate initial test when insulin resistance is suspected clinically 3
Clinical Applications and Predictive Value
The BMP serves as a powerful risk stratification tool beyond its individual components. When combined into a total risk score adjusted for age and sex, the BMP demonstrates exceptional predictive ability for mortality at 30 days (area under curve 0.887), 1 year (0.850), and 5 years (0.858) 4. This predictive capacity is independent of the Framingham Risk Score 4.
Standard Clinical Use
- Routine screening for patients with hypertension, diabetes, cardiovascular disease, or chronic kidney disease requires BMP assessment 1
- Resistant hypertension evaluation mandates a basic metabolic profile as part of the biochemical workup 1
- Chronic kidney disease monitoring requires BMP to calculate estimated glomerular filtration rate (eGFR) from creatinine 1
Interpretation Strategy
The BMP parameters are categorized as low, normal, or high based on standard reference ranges, with glucose categorized as normal, intermediate, or high, and creatinine ≥2 mg/dL further categorized as very high 4. This categorical approach optimizes the predictive utility of the panel 4.
Common Clinical Pitfalls
Do not order individual BMP components separately when a complete panel is indicated, as this fragments the assessment of interconnected metabolic processes 2. The electrolytes, kidney markers, and acid-base indicators must be considered together for accurate clinical interpretation 2.
Avoid using adjusted body weight calculations for BMP interpretation in patients with edema, as the standard approach uses post-dialysis or edema-free measurements 1. For patients between 95% and 115% of standard body weight, actual edema-free body weight can be used effectively 1.
Monitor serum bicarbonate monthly in maintenance dialysis patients to detect metabolic acidosis, which increases protein degradation and decreases albumin synthesis 1. Correction should target bicarbonate ≥22 mmol/L through higher dialysate bicarbonate concentrations (38 mmol/L) or oral supplementation 1.