Bicarbonate deficiency, also known as metabolic acidosis, is an important but often overlooked complication in cats with kidney disease. A comprehensive 10-year study of 618 cats has provided valuable insights into how common this problem is and how it relates to kidney function and mineral imbalances.
What the Study Found
The research examined cats diagnosed with acute kidney injury (AKI), acute-on-chronic kidney disease (ACKD), and chronic kidney disease (CKD). The findings revealed that nearly half (45%) of all cats studied had bicarbonate deficiency. Of these affected cats, 63% had moderate deficiency (12-16 mmol/L) while 37% had severe deficiency (below 12 mmol/L).
Interestingly, the prevalence varied significantly by disease type. Cats with AKI showed the highest rate at 58%, followed closely by ACKD at 60%, while CKD cats had a lower rate of 38%. This difference was statistically significant and suggests that acute kidney conditions may have a more immediate impact on acid-base balance.
The Connection to Disease Severity
The study found clear relationships between bicarbonate levels and various markers of kidney disease. In cats with AKI and CKD, lower bicarbonate levels correlated with higher creatinine, phosphate, and calcium-phosphate product (CaxP). For ACKD cats, the correlation was seen only with creatinine and phosphate levels.
As kidney disease worsened, bicarbonate deficiency became more common and severe in both AKI and CKD patients. This progression emphasizes the importance of monitoring bicarbonate levels as kidney disease advances.
Mineral Imbalance and Acidosis
One of the most interesting findings involved the relationship between mineral imbalance and bicarbonate deficiency. Cats with elevated CaxP (above 70 mg²/dL²) were significantly more likely to have bicarbonate deficiency. However, 21% of cats with elevated CaxP maintained normal bicarbonate levels, suggesting that mineral imbalance and acidosis don’t always occur together.
This finding is clinically important because it reminds us that these complications can develop independently and should be monitored separately.
Clinical Implications
For veterinary professionals, this study highlights several important points. First, bicarbonate deficiency is extremely common in cats with kidney disease, affecting nearly half of all patients. Second, cats with acute kidney conditions may be at higher risk than those with chronic disease. Third, the severity of bicarbonate deficiency tends to increase as kidney disease progresses.
Regular monitoring of bicarbonate levels, along with kidney function markers and mineral balance, is essential for comprehensive patient management. While this study didn’t evaluate treatment outcomes, it reinforces current IRIS guidelines that recommend addressing bicarbonate deficiency when levels fall below 16 mmol/L.
