Does a Basic Metabolic Panel Include Serum Creatinine and eGFR?
Yes, a Basic Metabolic Panel (BMP) includes serum creatinine, and most clinical laboratories will automatically calculate and report eGFR alongside the creatinine value. 1, 2
What the BMP Contains
A BMP routinely includes serum creatinine measurement, which is one of the standard components of this panel along with electrolytes (sodium, potassium, chloride, bicarbonate), glucose, and blood urea nitrogen (BUN). 2
Clinical laboratories are directed to automatically report eGFR in addition to serum creatinine concentrations using validated equations, as this is a laboratory implementation standard established by KDIGO guidelines. 1
The eGFR should be reported rounded to the nearest whole number and relative to a body surface area of 1.73 m² using the units mL/min per 1.73 m², and any eGFR values below 60 mL/min per 1.73 m² should be flagged as being low. 1
How eGFR is Calculated from Your BMP
The eGFR is calculated using validated equations that incorporate the serum creatinine value from your BMP along with demographic variables (age, sex, and race), without requiring any additional testing or urine collection. 1, 3
The most commonly used equations are the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) and MDRD (Modification of Diet in Renal Disease) formulas, which automatically convert your creatinine result into an estimated GFR. 1, 4
KDIGO guidelines recommend using eGFR based on serum creatinine (eGFRcr) as the initial test for evaluation of kidney function in routine clinical practice. 1, 2
Clinical Implications
The eGFR serves as the best available index of kidney function and is used to diagnose chronic kidney disease, classify its stages, and monitor disease progression. 1
Normal eGFR is typically >60 mL/min/1.73 m², and values below this threshold may indicate chronic kidney disease according to KDIGO classification. 2
For routine monitoring of kidney function, continuing to use the eGFRcr from your BMP is appropriate as the initial assessment, with consideration for cystatin C-based eGFR or measured GFR only in specific circumstances where creatinine-based estimates may be inaccurate. 1, 2, 3
Important Caveats
eGFR may be less accurate in patients with extremes of muscle mass, very elderly patients, or those with extremes of body size, as creatinine has significant non-GFR variability from muscle mass that is not adequately accounted for in eGFR equations. 1, 3
The laboratory must use standardized creatinine assays with calibration traceable to international standards (coefficient of variation <2.3%, bias <3.7%) to ensure accurate eGFR calculation, preferably using enzymatic methods. 1
When eGFR is thought to be inaccurate, consider measured creatinine clearance with timed urine collection or measured GFR using exogenous markers, particularly when treatment decisions depend on accurate GFR assessment. 1, 3