Bicarbonate renal handling

The kidneys not only secrete hydrogen ions but they also regenerate bicarbonate ions. The renal handling of electrolytes also influences acid-base balance. 

The pH of urine is dependent on the cationic and anionic composition, with the cationic products of normal metabolism buffered by the renal handling of bicarbonate and dietary protein content affecting urinary pH. In catabolic states associated with severe toxicity, the urinary pH may be lowered. Thus, changes of pH may reflect major metabolic perturbations, changes in tubular function, or the presence of xeno-biotics and/or their metabolites in urine. 

The buffering which occurs in respiratory alkalosis and the changes in renal handling of bicarbonate are the converse of those in respiratory acidosis. It is... 

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