Figure 1.

Urinary acid excretion may identify patients with CKD and normal tCO₂ who have subclinical metabolic acidosis. (A) The current metabolic acidosis treatment paradigm is to withhold alkali until serum tCO₂ falls below 22 mEq/L, in which case only 15% of patients with CKD receive alkali therapy. (B) An alternative paradigm assumes that patients with CKD and tCO₂ below a threshold value (represented as X), have either overt acidosis or subclinical metabolic acidosis and are potential candidates for alkali therapy. (C) Another possible approach would be to treat patients with CKD with tCO₂<22 mEq/L and those with subclinical metabolic acidosis defined by a normal tCO₂ and urinary acid excretion below a threshold value (represented as Y).