Categories: Endocrinology


Anion gap = Difference between the unmeasured cations and unmeasured  anions in the serum [artificial]

It will done with serum (has clotting factor removed) or with plasma [MOST OFTEN DONE WITH SERUM]

= ([Na+]) − ([Cl] + [HCO3]) = 10 , if greater than 12, IAGMA (when K+ is added, it is ~16)

*You can remove potassium due to its low concentration often having little or no effect on the gap

NORMALLY, there are cations > anions, so the gap is + [BUT plasma is overall electrically neutral]

Increase in this gap will result in increased ion gap acidosis [AKA a drop in the Cl- or Bicarbonate] which will result in more unmeasured anions needed to counter balance the sodium/ unmeasured cations.


There will be an increase in unmeasured acids, that will dissociate into their weak conjugate base (unmeasured anion) AND Hydrogen; the hydrogen will bind with HC03 and shift the equilibrium LEFT [reducing bicarbonate].


  • G — glycols ( ethylene glycol &  propylene glycol )
  • O — oxoproline, a metabolite of  acetaminophen 
  • L — L-lactate, the chemical responsible for  lactic acidosis 
  • D — D-lactate [REMEMBER: D/L are chiral enantiomers [optical isomers or non-superposable mirror image]
  • M —  methanol / metformin
  • A —  aspirin / salicylic acids
  • R —  renal failure 
  • K —  ketoacidosis , ketones generated from starvation, alcohol, and  diabetic ketoacidosis

 *There is also MUDPILES


1. Chapter 17. Pancreatic Hormones and Diabetes Mellitus. Greenspan’s Basic & Clinical Endocrinology, 9e  

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Dr. C Humphreys

Internal Medicine

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