What is the role of metabolism of proteins and dietary phosphate in the pathogenesis of metabolic acidosis?

Updated: Dec 08, 2020
  • Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN  more...
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The metabolism of proteins (ie, sulfur-containing amino acids) and dietary phosphate results in the formation of nonvolatile acids, H2 SO4 and H3 PO4. These acids first are buffered by the HCO3-/H2 CO3 system as follows:

H2 SO4 + 2NaHCO3 ↔Na2 SO4 + 2H2 CO3 ↔2H2 O + CO2

The net result is buffering of a strong acid (H2 SO4) by 2 molecules of HCO3- and production of a weak acid (H2 CO3), which minimizes the change in pH. The lungs excrete the CO2 produced, and the kidneys, to prevent progressive HCO3- loss and metabolic acidosis, replace the consumed HCO3- (principally by H+ secretion in the collecting duct). Some amino acids (ie, glutamate, aspartate) result in the formation of citrate and lactate, which, in turn, will be converted to HCO3-. The net result, in a typical American diet, is an acid load in the range of 50-100 mEq of H+ per day.

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