Photo Credit: Mohammed

In acute kidney injury, certain biomarkers—such as urine albumin-to-creatinine ratio and epidermal growth factor—are linked with likelihood of eGFR nonrecovery.

Serum creatinine elevations during hypertension treatment can complicate clinical management in the ambulatory setting, and few tools exist to determine whether kidney function will subsequently recover.

In an ancillary study of patients with acute kidney injury (AKI) from the SPRINT trial, researchers examined the relationship between urinary kidney biomarkers and subsequent kidney function in patients who developed an increase in serum creatinine during treatment for hypertension. The findings were published in the American Journal of Kidney Diseases.

A total of 652 patients who experienced ambulatory AKI, defined as a rise in serum creatinine of 0.3 mg/dL or more during follow-up, were included in the study. Joachim H. Ix, MD, and colleagues randomly assigned patients to the standard BP arm (<140 mm Hg; n=180) or the intensive BP arm (<120 mm Hg; n=472). The mean age of patients was 70 years, and the median increase in serum creatinine from baseline in both groups was 0.4 mg/dL.

The researchers measured eight urine biomarkers of glomerular injury and kidney tubule injury and dysfunction at baseline and at the time of ambulatory AKI. They then evaluated their association with subsequent changes in estimated glomerular filtration rate (eGFR).

Biomarkers Tied to Nonrecovery of eGFR

Overall, 67% of patients experienced nonrecovery in eGFR at 12 months after the ambulatory AKI episode. Dr. Ix and colleagues found that biomarkers reflecting worse glomerular injury and tubular dysfunction were associated with great risk of nonrecovery of kidney function.

Among biomarkers measured at the time ambulatory AKI was detected, higher urine albumin-to-creatinine ratio (odds ratio [OR],1.72; 95% CI, 1.10-2.70) and lower epidermal growth factor (OR, 0.46; 95% CI, 0.26-0.79) were associated with increased likelihood of subsequent nonrecovery in eGFR in the standard BP group. For the intensive BP group, higher urine α-1 microglobulin (OR, 1.45; 1.09-1.92), lower epidermal growth factor (OR, 0.62; 95% CI, 0.46-0.83), and lower kidney injury molecule-1 (OR, 0.75; 95% CI, 0.59-0.96) were associated with nonrecovery of eGFR. Similar findings were observed using baseline biomarker measurements and assessing 6-month eGFR recovery.

“Given the limitations of serum creatinine in differentiating hemodynamic versus intrinsic causes of ambulatory AKI, these results strengthen the evidence that a broader assessment of kidney health can provide information about long-term kidney function trajectories and demonstrate the potential role of kidney biomarkers in guiding the clinical management of ambulatory AKI during hypertension treatment,” the researchers wrote.