NIIGATA, Japan – A recent study conducted in Japan has unveiled a critical oversight in the routine care of patients with chronic kidney disease (CKD). The study highlights that serum bicarbonate levels, crucial for detecting metabolic acidosis, are infrequently measured, leaving this common CKD complication largely undiagnosed and untreated.
Metabolic acidosis, a frequent consequence of CKD, is linked to muscle wasting, bone disease, insulin resistance, accelerated kidney deterioration, and increased mortality. Clinical guidelines advise treatment when serum bicarbonate levels drop below 22 mEq/L. However, comprehensive real-world data from Asia have been scarce until now.
Study Highlights and Findings
In an effort to address this gap, Mai Tanaka and her team analyzed nationwide data from over 21 university hospitals via the Japan Chronic Kidney Disease Database Extension (JCKDDBEx). They assessed bicarbonate measurement, diagnosis, and treatment patterns in adults with CKD stages 3a–4 between 2014 and 2021.
The study’s key finding was stark: serum bicarbonate testing in routine CKD care was alarmingly rare.
“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 Mai Tanaka, the study’s lead author.
This infrequent testing resulted in a seemingly low prevalence of metabolic acidosis in the CKD population, reflecting limited measurement rather than the actual absence of the disease. However, among patients who were tested, nearly half met the criteria for metabolic acidosis, with prevalence increasing in more advanced CKD stages.
Global Context and Comparisons
The findings from Japan echo a broader global issue. A significant real-world analysis by Abramowitz and Whitlock across American and Canadian cohorts found that metabolic acidosis often goes undiagnosed in CKD cases. Fewer than 20% of patients received sodium bicarbonate therapy, with many cases remaining unrecognized in administrative records.
Acid retention accelerates kidney damage through pathways promoting tubulointerstitial injury and fibrosis, and dietary acid load complicates the scenario further. These findings suggest that the gap observed in Japan is part of a wider international pattern.
Clinical Guidelines and Implementation Challenges
Clinical guidelines, including those from the Japanese Society of Nephrology, recommend monitoring metabolic complications of CKD and correcting acidosis to maintain serum bicarbonate at or above 22 mEq/L. Yet, as Tanaka’s study indicates, routine implementation is inconsistent within standard CKD management workflows.
Despite being inexpensive and widely available, serum bicarbonate measurement is not routinely integrated into CKD care. The primary barrier appears to be a lack of awareness and integration into routine practice.
Opportunities for Improvement
This situation presents a clear opportunity for systemic assessment of bicarbonate levels in CKD patients, which could significantly enhance the detection of metabolic acidosis. Early recognition could allow timely initiation of alkali therapy or dietary interventions, both promising strategies for slowing kidney function decline.
For clinicians and healthcare systems, these findings underscore an actionable quality improvement target: incorporating bicarbonate testing into standard CKD monitoring panels. As CKD prevalence rises globally, particularly in aging populations, closing this assessment gap by ensuring routine evaluation of metabolic complications could be a practical and scalable strategy to improve patient outcomes.
The study’s message is both straightforward and powerful: metabolic acidosis in CKD may be hidden in plain sight, not because it is uncommon, but because it is not consistently measured.
