NIIGATA, Japan – A recent study conducted by a Japanese registry has uncovered a significant oversight in the routine care of patients with chronic kidney disease (CKD). The research reveals that serum bicarbonate levels, a critical indicator of metabolic acidosis, are seldom measured, leaving this common complication largely undetected and undertreated.
Metabolic acidosis is frequently associated with CKD and can lead to severe health issues such as muscle loss, bone disease, insulin resistance, accelerated kidney decline, and increased mortality. Despite clinical guidelines recommending treatment when serum bicarbonate levels fall below 22 mEq/L, there is a notable lack of real-world data from Asia on this issue.
Study Highlights: A Nationwide Data Analysis
In an effort to address this gap, Mai Tanaka and her colleagues analyzed data from over 21 university hospitals through the Japan Chronic Kidney Disease Database Extension (JCKDDBEx). The study focused on bicarbonate measurement, diagnosis, and treatment patterns in adults with CKD stages 3a–4 between 2014 and 2021.
The findings were striking: serum bicarbonate was rarely tested in routine CKD care.
“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,”
stated Mai Tanaka, the study’s lead author.
Due to infrequent testing, the prevalence of metabolic acidosis appeared low in the overall CKD population. However, among patients who did undergo bicarbonate testing, nearly half met the criteria for metabolic acidosis, with prevalence increasing alongside the progression of CKD.
Global Implications and Comparisons
The study revealed a concerning gap between the diagnosis and treatment of metabolic acidosis, even among those with serum bicarbonate levels below 22 mEq/L. Diagnosis and treatment rates were only 8.6% and 7.5%, respectively. Tanaka emphasized,
“The rate of serum bicarbonate measurement was low in CKD patients, suggesting that more attention to metabolic acidosis is needed in routine CKD care.”
Meanwhile, a large-scale analysis of American and Canadian cohorts led by Abramowitz and Whitlock found similar patterns, with metabolic acidosis often undiagnosed. Fewer than 20% of patients received sodium bicarbonate therapy, and many cases remained unrecognized in administrative records. These findings suggest that the issue observed in Japan reflects a broader global pattern.
Clinical Guidelines and Potential Solutions
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. However, Tanaka’s study indicates that routine implementation of these guidelines is inconsistent.
Serum bicarbonate measurement is both inexpensive and widely available. The primary barrier appears to be a lack of awareness and integration into routine care. This presents a clear opportunity for systemic assessment of bicarbonate levels in CKD patients, which could significantly improve the detection of metabolic acidosis.
Earlier recognition may allow for timely initiation of alkali therapy or dietary interventions, both promising strategies for slowing kidney function decline. For clinicians and health systems, these findings highlight an actionable quality improvement target: incorporating bicarbonate testing into standard CKD monitoring panels.
Looking Ahead: Addressing the Hidden Threat
As CKD prevalence rises globally, particularly in aging populations, closing this assessment gap by ensuring that metabolic complications are routinely evaluated could represent a practical and scalable strategy to improve patient outcomes. The study’s message is clear yet powerful: metabolic acidosis in CKD may be hidden in plain sight, not due to its rarity, but because it is not consistently measured.
