A recent study published on Mar. 16 found that metabolic acidosis, a common complication of chronic kidney disease (CKD), is frequently left undiagnosed and untreated in Japan due to infrequent measurement of serum bicarbonate levels.
This issue matters because metabolic acidosis can lead to muscle loss, bone disease, insulin resistance, faster kidney decline, and higher mortality rates among CKD patients. Clinical guidelines recommend treating the condition when serum bicarbonate falls below 22 mEq/L, but real-world data from Asia have been limited until now.
Mai Tanaka and colleagues analyzed nationwide data from more than 21 university hospitals using the Japan Chronic Kidney Disease Database Extension (JCKDDBEx). They evaluated how often bicarbonate was measured and how often metabolic acidosis was diagnosed and treated in adults with CKD stages 3a–4 between 2014 and 2021. The researchers found that "the annual measurement rate of serum bicarbonate levels in Japanese patients with CKD stages 3a to 4 was consistently below 10%, suggesting that metabolic acidosis itself may be underassessed," said Tanaka.
Because testing was so rare, the overall prevalence of metabolic acidosis appeared low. However, among those who were tested, nearly half met the criteria for the condition, with its prevalence increasing as CKD advanced. Even when patients had low serum bicarbonate levels (below 22 mEq/L), only about one in twelve received a diagnosis or treatment for metabolic acidosis. "The rate of serum bicarbonate measurement was low in CKD patients, suggesting that more attention to metabolic acidosis is needed in routine CKD care," Tanaka said.
Similar trends have been observed internationally. A large analysis across American and Canadian cohorts led by Abramowitz and Whitlock showed that fewer than one-fifth of patients received sodium bicarbonate therapy for metabolic acidosis, with many cases going unrecognized in administrative records. Acid retention can worsen kidney damage through pathways promoting injury and fibrosis; dietary acid load adds further risk.
Guidelines from organizations such as the Japanese Society of Nephrology recommend monitoring for complications like metabolic acidosis and correcting it when present. Despite this guidance—and the fact that serum bicarbonate tests are inexpensive—the study suggests routine implementation remains inconsistent due to lack of awareness rather than technical barriers.
The findings point toward an opportunity for quality improvement: adding regular bicarbonate testing to standard CKD monitoring could help detect hidden cases of metabolic acidosis earlier. This could allow timely interventions such as alkali therapy or dietary changes to slow kidney function decline. As global rates of CKD rise—especially among older populations—ensuring routine assessment for complications like metabolic acidosis may help improve patient outcomes.
