CLINICAL CASE 52: ANSWERS and SUMMARY

TRUE OR FALSE: SEVERE METABOLIC OR RESPIRATORY ALKALOSIS CAN LEAD TO AN ANION GAP METABOLIC ACIDOSIS.

True 60%

False 40%

Severe alkalemia can cause an increase in anion gap.  Alkalemia leads to glycolysis in the liver and a mild lactic acidosis. In severe volume contracted state, the anion gap can be seen with change in valence of circulating proteins to preserve extracellular volume.  

A prior post had discussed this as well. 

See the references below:

Emmett M, Narins R. Clinical use of the anion gap. Medicine 1977; 56:38–45.

Kraut J, Madias N. Serum anion gap: its uses and limitations in clinical medicine. Clin J Am Soc Nephrol 2007; 2: 162–174.

Consult Rounds: Alkalemia causing Metabolic Acidosis

Can severe metabolic or resp alkalemia lead to Metabolic Acidosis?
Yes it can!!

Metabolic alkalosis, if from vomiting or diuretic use can be associated with a small increment of anion gap ( around 4-6meq/L) and this is ofcouse if no other disorder has been identified.  Why? Largely due to increase in albumin and some due to other increase in anionic proteins.  

Serum anion gap does not change notably in acute respiratory alkalosis, but small increases up to 3meq/L have been observed in chronic respiratory alkalosis.  

Alkalemia also causes glycolysis in the liver and a mild lactic acidosis (seen in our patient). In addition, in a volume contracted patient, the change in anion gap can be due to the change in valence of circulating proteins to preserve extracellular volume.

Ref:

http://www.ncbi.nlm.nih.gov/pubmed/401925

http://www.ncbi.nlm.nih.gov/pubmed/17699401

http://www.ncbi.nlm.nih.gov/pubmed/18974769