View source for Basic Metabolic Panel

==Background==
The '''Basic Metabolic Panel''' (BMP), often referred to as a '''Chem-7''' or '''SMA-7''', is one of the most frequently ordered laboratory tests in the Emergency Department. It provides a rapid assessment of fluid status, electrolytes, renal function, and glucose levels.<ref name="pmid32443130">Bertschi LA. Abnormal Basic Metabolic Panel Findings: Implications for Nursing. Am J Nurs. 2020 Jun;120(6):48-55. [https://pubmed.ncbi.nlm.nih.gov/32443130/ PubMed Abstract]</ref>

Including [[Calcium]] technically makes the panel a '''Chem-8'''. It differs from the [[Comprehensive Metabolic Panel]] (CMP) by the lack of [[Liver Function Tests]] (LFTs).

==Components and Reference Ranges==
''Reference ranges vary by laboratory. Typical adult values are listed below.''<ref name="pmid25295502">Berend K, de Vries AP, GansRO. Physiological approach to assessment of acid-base disturbances. N Engl J Med. 2014 Oct 9;371(15):1434-45. [https://pubmed.ncbi.nlm.nih.gov/25295502/ PubMed Abstract]</ref>

{| class="wikitable"
! Component !! Abbreviation !! Normal Range (US) !! SI Units
|-
| [[Sodium]] || Na || 135 – 145 mEq/L || 135 – 145 mmol/L
|-
| [[Potassium]] || K || 3.5 – 5.0 mEq/L || 3.5 – 5.0 mmol/L
|-
| [[Chloride]] || Cl || 95 – 105 mEq/L || 95 – 105 mmol/L
|-
| [[Bicarbonate]] (Total CO2) || HCO3 / CO2 || 22 – 29 mEq/L || 22 – 29 mmol/L
|-
| [[Blood Urea Nitrogen]] || BUN || 7 – 20 mg/dL || 2.5 – 7.1 mmol/L
|-
| [[Creatinine]] || Cr || 0.6 – 1.2 mg/dL || 53 – 106 µmol/L
|-
| [[Glucose]] || Glu || 70 – 100 mg/dL (fasting) || 3.9 – 5.6 mmol/L
|-
| [[Calcium]] || Ca || 8.5 – 10.2 mg/dL || 2.1 – 2.6 mmol/L
|}

==Interpretation==

===Sodium (Na)===
* '''[[Hyponatremia]] (<135):'''
** <120 mEq/L is a critical value (Risk of [[Seizure]], coma).<ref name="pmid10816188">Adrogué HJ, Madias NE. Hyponatremia. N Engl J Med. 2000 May 25;342(21):1581-9. [https://pubmed.ncbi.nlm.nih.gov/10816188/ PubMed Abstract]</ref>
** Assess volume status (Hypovolemic, Euvolemic, Hypervolemic).
** ''Pearls:'' rule out Pseudohyponatremia (Hyperlipidemia/Hyperproteinemia) and Hyperglycemic induced (Corrected Na = Measured Na + 1.6 * [(Glucose - 100) / 100]).<ref name="pmid10225241">Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999 Apr;106(4):399-403. [https://pubmed.ncbi.nlm.nih.gov/10225241/ PubMed Abstract]</ref>
* '''[[Hypernatremia]] (>145):'''
** Almost always implies free water deficit ([[Dehydration]]).
** Calculate Free Water Deficit.

===Potassium (K)===
* '''[[Hyperkalemia]] (>5.0):'''
** ''Emergency:'' >6.0 or any ECG changes ([[Peaked T waves]], QRS widening, Sine wave).
** Causes: [[Renal Failure]], [[Rhabdomyolysis]], missed dialysis, [[Acidosis]] (shifts K out of cells), [[Hemolysis]] (lab error).<ref name="pmid18272089">Montague BT, Ouellette JR, Buller GK. Retrospective review of the frequency of ECG changes in hyperkalemia. Clin J Am Soc Nephrol. 2008 Mar;3(2):324-30. [https://pubmed.ncbi.nlm.nih.gov/18272089/ PubMed Abstract]</ref>
* '''[[Hypokalemia]] (<3.5):'''
** Causes: Diuretics, GI loss (diarrhea/vomiting).
** ''Emergency:'' Arrhythmias, U-waves, respiratory muscle weakness.
** Always check and replete [[Magnesium]] with K.

===Chloride (Cl)===
* Generally follows Sodium status.
* '''Hyperchloremia:''' Often iatrogenic from large volume [[Normal Saline]] resuscitation (Non-gap metabolic acidosis).
* '''Hypochloremia:''' Gastric outlet obstruction/vomiting (Metabolic alkalosis).<ref name="pmid25295502" />

===Bicarbonate (CO2)===
* Represents total venous CO2 content (mostly HCO3).
* '''Low (<22):''' [[Metabolic Acidosis]] (most common in ED) or compensation for respiratory alkalosis.
** Calculate [[Anion Gap]] (see below).
* '''High (>29):''' [[Metabolic Alkalosis]] or compensation for chronic [[COPD]] (Respiratory acidosis).

===BUN and Creatinine===
* '''[[Acute Kidney Injury]] (AKI):'''
** '''Prerenal:''' BUN:Cr ratio > 20:1. (Dehydration, poor perfusion).
** '''Intrinsic:''' BUN:Cr ratio < 15:1. (ATN, AIN, Glomerulonephritis).
** '''Postrenal:''' Obstruction (Stones, BPH).
* ''Pearl:'' Isolated elevated BUN (with normal Cr) is a sensitive indicator for [[Upper GI Bleed]] (digested hemoglobin).<ref name="pmid22396504">Srygley FD, Gerardo CJ, Tran T, Fisher DA. Does this patient have a severe upper gastrointestinal bleed? JAMA. 2012 Mar 14;307(10):1072-9. [https://pubmed.ncbi.nlm.nih.gov/22396504/ PubMed Abstract]</ref>

===Glucose===
* '''[[Hypoglycemia]] (<70):''' AMS, diaphoresis, seizure. Treat with D50/D10.
* '''[[Hyperglycemia]]:'''
** >250 with AG Metabolic Acidosis + Ketones = [[Diabetic Ketoacidosis]] (DKA).<ref name="pmid2754687">Kitabchi AE, Umpierrez GE, Murphy MB, et al. Management of hyperglycemic crises in patients with diabetes. Diabetes Care. 2001 Jan;24(1):131-53. [https://pubmed.ncbi.nlm.nih.gov/11194218/ PubMed Abstract]</ref>
** >600 with high osmolarity + no acidosis = [[Hyperosmolar hyperglycemic state]].

==Calculations==

===Anion Gap (AG)===
* Used to differentiate causes of Metabolic Acidosis.<ref name="pmid17699401">Kraut JA, Madias NE. Serum anion gap: its uses and limitations in clinical medicine. Clin J Am Soc Nephrol. 2007 Jan;2(1):162-74. [https://pubmed.ncbi.nlm.nih.gov/17699401/ PubMed Abstract]</ref>
* Formula: <math>AG = Na - (Cl + HCO3)</math>
* '''Normal:''' 8–12 (varies by assay; >12 usually abnormal).
* '''High Gap Causes (MUDPILES):''' Methanol, Uremia, DKA, Paraldehyde, Iron/INH, Lactic Acidosis, Ethylene Glycol, Salicylates.
* ''Note:'' [[Hypoalbuminemia]] lowers the baseline AG. Corrected AG = Observed AG + 2.5 * (4 - Albumin).

===Corrected Sodium (Hyperglycemia)===
* Formula: {Corrected Na} = {Measured Na} + 0.016 {Glucose} - 100)<ref name="pmid10225241" />

===Calcium Correction===
* If albumin is low, total calcium appears falsely low.
* Formula: {Corrected Ca} = {Measured Ca} + 0.8  (4 - {Albumin})<ref name="pmid4758544">Payne RB, Little AJ, Williams RB, Milner JR. Interpretation of serum calcium in patients with abnormal serum proteins. Br Med J. 1973 Dec 15;4(5893):643-6. [https://pubmed.ncbi.nlm.nih.gov/4758544/ PubMed Abstract]</ref>
* Or check an '''Ionized Calcium''' (iCa).

==See Also==
* [[Comprehensive Metabolic Panel]]
* [[Anion Gap]]
* [[Acute Kidney Injury]]
* [[Hyperkalemia]] / [[Hypokalemia]]
* [[Hypernatremia]] / [[Hyponatremia]]

==References==
{{reflist|2}}

[[Category:Critical Care]]
[[Category:Renal]]