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Old 09-08-2011
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Question Question about anion gap in metabolic acidosis.

In RTA type 2, the function of resorption of bicarbonate is impaired.
so more chloride comes with sodium, and that is why Anion gap will not be increased in that disease.

I wonder how diarrhea is in the same category as RTA ( normal anion gap type). My guess is that due to the low level of bicarbonate in serum(we lost bicarbonate by diarrhea) , more chloride comes with sodium in renal tubule.

If it is right, i think high anion gap metabolic acidosis such as lactic acidosis cannot be in high anion gap metabolic acidosis. because, by increased acid, the level of bicarbonate will be decreased. like in diarrhea, the level of bicarbonate in serum
will be decreased, so more Chloride will be reabsorbed. it means lactic acidosis is normal anion gap acidosis.

what is wrong in my thought?
thank you for your help!!
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Old 01-21-2012
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I have been wondering about that for ages.

I quote from kaplan vids that the renal system is leaky for choride.
The following is my own understanding about this:
Whenever bicarb crosses a cell Cl- crosses in the opposite direction either via antiporter as in the pancreas or due to the electrical gradient created by bicarb monement. If that is correct , this explains that in any case where there is loss of bicarb there will be gain of Cl and hence no anion gap

I think that in diarrhea there is increase secretion of bicarb form the pancreas to replenish that lost from the GI , and therefore more cl- absorbed!!!

PLZ anyone, correct me .
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Old 01-21-2012
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In lactic acidosis, the primary pathology is increased H+ ions in the blood. Lactic acid accumulates and that is not measured in the anion gap calculation.

Bicarbonate is low, true. Chloride will increase, true. But that would only balance the Na + K - (bicarb and chloride) equation it won't offset the build up of lactic acid.
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amit chahar (07-05-2012)


Electrolytes-, Physiology-, Renal-

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