during starvation results in the production of H+


production. Depending on the composition of the diet and considering protein intakes of 100 g/day, the intake of sulphur-containing amino acids is about 3g/day, which would lead to H+ day.”


production is reported to account for 25 to 70 mEq/day of H+


production of approximately 20 mEq/


          “Cationic amino acids (i.e. mainly arginine and lysine) contain an additional amino group, which is protonated at body pH, and their metabolism leads to the production of acid.”


        


“Conversely, anionic amino acids (glutamate, aspartate), which contain an additional carboxyl group, contribute to the production of alkali (or consumption of acid) when they are metabolized.”


cases, HCO-3


                                   “…some ingested organic acids cannot be fully metabolized in the body (e.g. uric, oxalic or hippuric acids) and their organic anions are formed as end products of metabolism with an equivalent consumption of HCO¬-3


(bicarbonate) and retention of H+ potential base.” is not generated, which represents a loss of


What is 


“The loss of bicarbonate due to the incomplete metabolism of organic acids is reported to be equivalent to an H+ addition/retention of 40 mEq.”


  “The most important organic sources of alkalis in the diet are organic acids that are ingested in the form of salts or organic anions (e.g. citrate, malate and lactate).


lead to the production of HCO)-3 when they are oxidized in the course of metabolism…”


They


“Proteins are also buffers because of their amine (NH2) and carboxylic acid (COOH) groups.”


          Poupin et al note:


          


90 . In both


…This


  mainly in the form of H2


Hydrogen ions are usually buffered by HCO-3 CO2


by the lungs.”


   “Ammonium (NH+


metabolism of glutamine by the kidneys.” 4) is excreted in urine through the


must be regenerated, which is the other role of the kidneys.        ‘new’ bicarbonate to replace that lost during buffering mechanisms.”


must be sustained and HCO-3


                           and to sustain the bicarbonate buffer system, the blood concentration of HCO-3


and HCl (from cationic amino acids), which dissociate into H+ and the corresponding anions SO2


SO4


(from sulphur amino acids) -4


or Cl-. excreted as


  “The other way to generate ‘new bicarbonates’ occurs through glutamine catabolism in the kidneys.”


          “In normal acid-base balance, the kidneys extract and catabolize very little of the plasma glutamine, but during acute and chronic acidosis the extraction of glutamine by 


                                                


                    “Sulphur amino acids are thought to be responsible for most of the acidifying potential of the diet. The end product of their metabolism is sulphate (SO2


excreted in the urine. Since sulphate is rarely ingested in another form than sulphur amino acids, urinary sulphate excretion is proportional to H+


4-), which is oxidation of sulphur amino acids. However, it has been


THE ORIGINAL INTERNIST  (Continued on page 94)


production from the


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