A new study of over 51,000 people with chronic kidney disease (CKD) has uncovered a serious but often-overlooked condition that nearly triples the risk of death within two years. Metabolic acidosis, a buildup of acid in the blood that develops when kidneys can't filter properly, emerged as a powerful predictor of mortality independent of other health factors. The findings suggest doctors need to pay closer attention to this marker during routine kidney disease monitoring.

What Is Metabolic Acidosis and Why Does It Matter for Kidney Patients?

Metabolic acidosis occurs when the body accumulates too much acid or loses too much bicarbonate, a natural buffer that keeps blood pH balanced. In healthy people, the kidneys regulate this balance automatically. But as kidney function declines, this regulatory system breaks down, allowing acid to build up. For patients with CKD (chronic kidney disease), this isn't just a side effect; it appears to be a major warning sign .

Researchers led by Dr. Navdeep Tangri examined data from nearly 52,000 patients with non-dialysis dependent CKD stages 3 through 5 between 2007 and 2017. They compared two-year mortality rates between patients with metabolic acidosis and those with normal serum bicarbonate levels at the start of the study .

How Severe Is the Mortality Risk?

The numbers were striking. Among patients with metabolic acidosis, 30.9% died within two years, compared to just 10.2% of those without the condition. This threefold difference held true across all stages of CKD, from stage 3 to stage 5 .

Even more concerning, the risk increased steadily with acid levels. For every 1 mEq/L drop in serum bicarbonate (the marker doctors use to measure acid buildup), patients faced a 15% higher risk of death from any cause. This relationship remained strong even after researchers accounted for age, sex, race, diabetes, high blood pressure, heart failure, and baseline kidney function .

"The presence of metabolic acidosis was associated with a high 2-year risk of all-cause death in patients with CKD. This finding was independent of age, sex, race, pre-existing conditions, and baseline eGFR and ACR," stated Dr. Navdeep Tangri and colleagues.

Dr. Navdeep Tangri, MD, PhD, and colleagues, National Kidney Foundation 2020 Spring Clinical Meetings

Why Isn't This Being Caught More Often?

The study reveals a troubling gap in kidney disease care. Metabolic acidosis is measurable through a simple blood test that checks serum bicarbonate levels, yet it often goes undetected or untreated in routine clinical practice. The research suggests that patients with CKD stages 3 through 5 should have regular bicarbonate monitoring, especially since the condition is both identifiable and potentially manageable .

The findings were consistent across different patient subgroups and remained significant even when researchers adjusted their analysis for various complicating factors. This consistency strengthens the evidence that metabolic acidosis is not just a marker of kidney disease progression, but an independent risk factor that deserves clinical attention .

Steps to Monitor and Manage Kidney Health

• Request Bicarbonate Testing: Ask your doctor to include serum bicarbonate levels in your routine blood work if you have CKD. This simple test can reveal metabolic acidosis before it causes serious complications.
• Track Kidney Function Regularly: Ensure you have at least annual testing of your estimated glomerular filtration rate (eGFR), which measures how well your kidneys filter waste. Consistent monitoring helps catch changes early.
• Discuss Acid-Base Balance: If you have CKD, ask your nephrologist or primary care doctor about your acid-base status and whether your bicarbonate levels are in a healthy range. Don't assume it's being monitored unless you confirm it.

What Should Kidney Patients Do Now?

If you have been diagnosed with CKD, this research underscores the importance of comprehensive monitoring beyond just kidney function numbers. The study included patients with two or more consistent bicarbonate tests spaced 28 to 365 days apart, suggesting that regular measurement is both feasible and necessary .

The takeaway for patients is clear: metabolic acidosis is a serious but treatable complication of kidney disease that deserves the same attention as blood pressure or blood sugar control. By catching it early through routine testing, patients and their doctors can potentially intervene before it contributes to worse health outcomes. If you have CKD, make sure your care team is monitoring your acid-base balance as part of your regular kidney disease management.