Baltimore, MD—In most cases, acute tubulointerstitial nephritis (AIN), a medical condition that causes inflammation of the kidneys and can lead to acute kidney injury (AKI), is linked to the use of certain medications.

In fact, in an estimated 70% of patients, AIN is thought to be the result of medications used to treat gastroesophageal reflux disease, bacterial infections, and cancer, according to Chirag Parikh, MBBS, PhD, director of the Division of Nephrology at Johns Hopkins Medicine and corresponding author of a study led by Johns Hopkins in conjunction with the Yale School of Medicine.

As a result, Dr. Parikh noted, clinicians often assume AIN—although rare—is present to avoid kidney biopsy risks and then treat the symptoms by withdrawing all drugs that are potential culprits while administering corticosteroid therapy.

The study published in the Journal of Clinical Investigation reported the identification of a biomarker found via a simple urine test that can be used to diagnose AIN. The researchers advised that testing for a protein called CXCL-9 in urine could be a noninvasive way to diagnose AIN without having to do a kidney biopsy.

Dr. Parikh stated in a Johns Hopkins press release that the use of a biomarker can help avoid overtreatment when an AIN diagnosis is incorrect. Medications discontinued might include antibiotics and anticancer agents, while corticosteroid therapy carries risks such as hyperglycemia, bone loss, gastrointestinal hemorrhage, and infection.

“Evaluation of a patient with AKI requires a thorough evaluation of its underlying cause and development of a personalized treatment plan focused on the underlying etiology and mechanism of injury,” Dr. Parikh explained.

For the study, the urine of more than 200 hospital patients with AKI was tested for 180 potential biomarkers to identify the top AIN-associated CXCL-9 protein. The researchers found patients with AIN had a much higher level of the protein in their urine compared with those without AIN. Kidney tissue samples confirmed the results.

The article advised, “A major challenge in the clinical care of patients with AKI is differentiating AIN from other causes of AKI. Most patients with AIN have no disease-specific signs or symptoms. Clinically available tests, such as urine eosinophils, urine microscopy for WBC casts, and imaging tests have poor accuracy. Therefore, diagnosis of AIN often requires a kidney biopsy, which adds procedure-related risks. It also leads to a delay in care that is associated with lower chances of kidney function recovery.”

Approximately one-half of patients have significant, permanent kidney damage after an episode of AIN, the study noted.

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.

 « Click here to return to Weekly News.