Anion gap

Pathophysiology sample values
BMP/ELECTROLYTES:
Na+ = 140 Cl = 100 BUN = 20 /
Glu = 150
\
K+ = 4 CO2 = 22 PCr = 1.0
ARTERIAL BLOOD GAS:
HCO3 = 24 paCO2 = 40 paO2 = 95 pH = 7.40
ALVEOLAR GAS:
pACO2 = 36 pAO2 = 105 A-a g = 10
OTHER:
Ca = 9.5 Mg2+ = 2.0 PO4 = 1
CK = 55 BE = −0.36 AG = 16
SERUM OSMOLARITY/RENAL:
PMO = 300 PCO = 295 POG = 5 BUN:Cr = 20
URINALYSIS:
UNa+ = 80 UCl = 100 UAG = 5 FENa = 0.95
UK+ = 25 USG = 1.01 UCr = 60 UO = 800
PROTEIN/GI/LIVER FUNCTION TESTS:
LDH = 100 TP = 7.6 AST = 25 TBIL = 0.7
ALP = 71 Alb = 4.0 ALT = 40 BC = 0.5
AST/ALT = 0.6 BU = 0.2
AF alb = 3.0 SAAG = 1.0 SOG = 60
CSF:
CSF alb = 30 CSF glu = 60 CSF/S alb = 7.5 CSF/S glu = 0.6

The anion gap[1][2] (AG or AGAP) is a value calculated from the results of multiple individual medical lab tests. It may be reported with the results of an electrolyte panel, which is often performed as part of a comprehensive metabolic panel.[3]

The anion gap is the quantity difference between cations (positively charged ions) and anions (negatively charged ions) in serum, plasma, or urine. The magnitude of this difference (i.e., "gap") in the serum is calculated to identify metabolic acidosis. If the gap is greater than normal, then high anion gap metabolic acidosis is diagnosed.

The term "anion gap" usually implies "serum anion gap", but the urine anion gap is also a clinically useful measure.[4][5][6][7]

  1. ^ Oh MS, Carroll HJ (1977). "The anion gap". N. Engl. J. Med. 297 (15): 814–7. doi:10.1056/NEJM197710132971507. PMID 895822.
  2. ^ Gabow PA, Kaehny WD, Fennessey PV, Goodman SI, Gross PA, Schrier RW (1980). "Diagnostic importance of an increased serum anion gap". N. Engl. J. Med. 303 (15): 854–8. doi:10.1056/NEJM198010093031505. PMID 6774247.
  3. ^ "Electrolytes: Common Questions: What is anion gap?". Lab Tests Online. American Association for Clinical Chemistry. 24 February 2015. Retrieved 10 November 2015.
  4. ^ Emmett M.; Narins R.G. (1977). "Clinical use of the anion gap". Medicine. 56 (1): 38–54. doi:10.1097/00005792-197701000-00002. PMID 401925.
  5. ^ "Urine Anion Gap: Acid Base Tutorial, University of Connecticut Health Center". Archived from the original on 21 November 2008. Retrieved 14 November 2008.
  6. ^ "Urine anion and osmolal gaps in metabolic acidosis". Retrieved 14 November 2008.
  7. ^ Kirschbaum B, Sica D, Anderson FP (June 1999). "Urine electrolytes and the urine anion and osmolar gaps". The Journal of Laboratory and Clinical Medicine. 133 (6): 597–604. doi:10.1016/S0022-2143(99)90190-7. PMID 10360635.