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Your Basic Metabolic Panel is a snapshot of your body's chemical balance — electrolytes, kidney function, and blood sugar in one draw. Here's what each of the 8 values means and how they work together.
Internal Medicine, Metabolic Disease ·
The essentials — before you read the full guide below.
Sodium, potassium, chloride, bicarbonate (electrolytes), BUN, creatinine (kidney), glucose (blood sugar), and calcium. Eight tests, one blood draw.
Sodium and potassium are the most immediately dangerous when abnormal — serious arrhythmias and neurological problems can develop rapidly with severe electrolyte imbalance.
The CMP includes everything in the BMP plus liver function tests (ALT, AST, ALP, bilirubin, albumin, total protein). BMP is ordered when liver screening isn't needed.
Glucose is more accurately measured fasting, but most BMP components are not fasting-dependent. Your doctor will specify if fasting is needed.
Reference Ranges
Use the interactive slider below, or read the range cards for a full clinical breakdown.
Drag to see what your Basic Metabolic Panel (BMP) means
The Science
The BMP tests are not independent numbers — they form an interconnected system. Sodium and potassium control electrical signalling in nerves and muscles. Bicarbonate and chloride indicate acid-base balance. BUN and creatinine reflect kidney filtration. Glucose shows immediate metabolic status. Calcium regulates muscle, nerve, and cardiac function. Interpreting them together identifies patterns a single test cannot.
Calculated as Na − (Cl + HCO₃), the anion gap detects unmeasured acids. An elevated gap (>12 mEq/L) indicates metabolic acidosis from causes like ketoacidosis, lactic acidosis, or toxin ingestion — invisible if you only look at individual values.
BUN and creatinine alone are insensitive kidney markers — they rise only after 50% of kidney function is lost. The BUN:creatinine ratio helps distinguish pre-renal (dehydration) from intrinsic kidney disease. eGFR, derived from creatinine, is the most useful kidney function estimate.
Potassium 3.5–5.0 mEq/L is normal; levels outside 2.5–6.5 mEq/L can cause fatal cardiac arrhythmias. Diuretics (especially thiazides and loop diuretics) commonly cause hypokalaemia — making potassium monitoring critical for patients on these drugs.
When to Test
These are the most common reasons a Basic Metabolic Panel (BMP) test is requested — from symptoms to routine screening.
Potassium abnormalities directly affect cardiac conduction. BMP is ordered urgently with ECG when arrhythmia is suspected.
Urgent useDiuretics alter sodium, potassium, and BUN. ACE inhibitors can raise potassium and creatinine. BMP monitoring is standard for patients on these medications.
Drug monitoringElectrolyte abnormalities (particularly sodium and potassium) cause neurological and muscular symptoms. BMP quickly identifies the metabolic cause.
Symptom screenBMP is standard pre-operative screening — electrolyte and kidney function must be confirmed before anaesthesia and fluid management.
Pre-op standardBMP is one of the most-ordered hospital panels — electrolytes and kidney function must be checked daily in many acute conditions.
Daily inpatientGlucose and kidney function (BUN, creatinine) are central to diabetes care. BMP screens for diabetic nephropathy and monitors glucose control.
Diabetes careTesting Schedule
Frequency depends on your current health status and your doctor's guidance.
Annual BMP as part of preventive health screening to establish metabolic baseline.
Electrolytes and kidney function are monitored daily in patients receiving IV fluids, diuretics, or with acute illness.
eGFR and electrolytes monitored every 3–6 months — frequency increases as CKD progresses.
BMP checked 1–2 weeks after initiating or changing diuretics or ACE inhibitors, then every 3–6 months when stable.
If Your Result Is Abnormal
Each abnormal value in the BMP has a specific downstream investigation pathway.
Any potassium outside 3.0–5.5 mEq/L or sodium outside 130–150 mEq/L should prompt an ECG to rule out cardiac involvement before further management.
Always ECG with K⁺/Na⁺ abnormalityHigh creatinine prompts eGFR calculation, urinalysis for protein/blood, and renal ultrasound if eGFR is below 60 mL/min/1.73m².
eGFR + urine proteinA BMP glucose above 7.0 mmol/L (or 126 mg/dL) fasting, confirmed on repeat testing, meets the diagnostic threshold for diabetes. HbA1c is next.
HbA1c to confirm diabetesUrine sodium and osmolality differentiate SIADH (urine Na >20 mEq/L) from hypovolaemic hyponatraemia (urine Na <20 mEq/L). This directs treatment — opposite management strategies.
Urine Na + osmolalityClinician-reviewed articles published in this category — referenced, sourced, and written for patients and practitioners alike.
Article
Learn what a sodium blood test reveals about hyponatremia and hypernatremia, their causes, symptoms, and treatment options for optimal health.
