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Old 07-26-2016
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Default problem about acid base balance and anion gap

in metabolic acidosis occuring in diarrhoea , type 1 and 2 renal tubular acidosis , no widening of anion gap , but all other meta. acidosis shows widening of anion gap, why ????? can anyone please explain it easily ?
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Old 07-26-2016
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I dont know if my method is right but i use to think anion gap that way:

If you have metabolic acidosis caused by production of an acid (eg DKA) or by an acid in general (eg methanol toxicity-formic acid..) then you have an increase in H+. That increase will consume HCO3- for neutralization . So you will have a decrease in HCO3- so you will see an increased AG.
If you see any mistakes in my method pls let me know
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Old 08-08-2016
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Hi there,

Metabolic acidosis is either due to loss of HCO3- or increased H+. When it's due to loss of HCO3-, Cl- increases to counteract that, effectively keeping the anion gap [Na - (HCO3 + Cl)] from increasing. When it's due to increased H+, Cl- stays the same, which lets the gap increase. Why is that:
Think of acid as HA. When acid is overproduced or is not excreted (as in DKO, AKI, CKD etc.), both a cation (H+) and an anion (A-) are added to the pool. Anion pool thus stays the same and Cl- doesn't need to counteract anything.
There is *no* anion gap, you see. It's just that A- is not taken into account (only Cl- and HCO3- are), producing a fake gap.

Hope this helps.
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