Tyson CC, Luciano A, Modliszewski JL, et al. - In this randomized order, cross-over study with controlled feeding, researchers sought to compare net acid excretion (NAE) among participants with and without chronic kidney disease (CKD), and also the NAE, blood pressure, and metabolomic response to bicarbonate supplementation. In a randomized order, cross-over fashion, participants were asked to consume a fixed–acid-load diet with bicarbonate supplementation (7 days) and with sodium chloride control (7 days). Patients suffering from CKD vs those without CKD were found to have lower acid elimination in the form of ammonium but also lower base removal such as citrate and other organic anions, a potential compensation to preserve acid-base homeostasis. Acid excretion in patients with CKD was shown to be reduced further but base excretion (eg, citrate) rose in response to alkali. Assessment of urine citrate, as an early and responsive marker of impaired acid-base homeostasis, is recommended.