METABOLIC acidosis may be defined as an excess of arterial blood hydrogen ion not caused by an increase in carbonic acid. This excess of hydrogen ion can be brought about in two basic ways:
Increase in strong acids in the body. This can be endogenous as with the increase in β-OH-butyric acid and acetoacetic acid in starvation ketosis or exogenous as with NH4Cl administration.
Loss of bicarbonate from the body, ie, diarrhea, from the kidneys, etc.
DOE RP. Metabolic Acidosis Nondiabetic. Arch Intern Med. 1965;116(5):717-728. doi:10.1001/archinte.1965.03870050071011