Anion gap: Difference between revisions
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==Background== | |||
AG = Na - (Cl + HCO3) | |||
Normal Anion Gap = 12+/-4 (8-16) <br/> | |||
Cutoffs for "normal" Anion Gap are laboratory and equipment specific. Newer technology and equipment have been shown to measure "low" AG in otherwise normal, healthy people. | |||
==Elevated Anion Gap== | ==Elevated Anion Gap== | ||
===DDx=== | ===DDx=== | ||
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==Low Anion Gap== | ==Low Anion Gap== | ||
===DDX=== | ===DDX=== | ||
*Lab error | *Lab error | ||
Revision as of 16:33, 7 February 2014
Background
AG = Na - (Cl + HCO3)
Normal Anion Gap = 12+/-4 (8-16)
Cutoffs for "normal" Anion Gap are laboratory and equipment specific. Newer technology and equipment have been shown to measure "low" AG in otherwise normal, healthy people.
Elevated Anion Gap
DDx
MUDPILES
- M - Methanol
- U - Uremia
- D - DKA
- P - Paraldehyde
- I - Iron, INH
- L - Lactic acidosis
- E - Ethylene glycol
- S - Salicylates
Also:
- Starvation/ETOH ketoacidosis
- CO, CN poisoning (incr. lactate)
Low Anion Gap
DDX
- Lab error
- Decreased "unmeasured" anions
- hypoalbuminemia
- Increased "unmeasured" cations
- Increased cationic paraprotein
- Multiple myeloma
- Polyclonal IgG gammopathy
- Pseudo
- Severe Hypernatremia (>170 meq/L)
- True conc of Na is underestimated
- Marked hyperlipidemia
- Leads to overestimation of plasma Cl conc)
- Bromide intoxication (e.g. for myasthenia gravis and some herbal medications)
- Machine mistakenly reads Br as Cl
- Severe Hypernatremia (>170 meq/L)
- AG falls by 2.5 meq/L for every 1 g/dL reduction in albumin concentration
See Also
Anion Gap and Osmolar Gap (High)
Source
Kaji Questions
MISTRY 6/06