The Caffeine-Kidney Connection

Matthew W. Harer, MD
Matthew Harer, MD, an assistant professor in the Division of Neonatology and Newborn Nursery, is conducting research on how caffeine citrate might reduce acute kidney injury in premature babies.

A medication derived from caffeine that neonatologists routinely use to prevent respiratory problems in premature babies may also help improve the health of their kidneys.

Earlier research led by Matthew Harer, MD, an assistant professor in the Division of Neonatology and Newborn Nursery, found that giving caffeine citrate in the first seven days after birth correlates with lower rates and severity of acute kidney injury (AKI).

Marked by a sudden decline in kidney function, AKI affects fluid balance, electrolytes, and urine production. It can result in poor long-term health outcomes: by age 5, 65 percent of children born prematurely who had AKI in the NICU already show signs of chronic kidney disease.

But because little is known about when AKI actually occurs, it not clear if there is an optimal time to administer caffeine citrate.

In Dr. Harer’s newest research project, he’s investigating whether noninvasive monitoring using near-infrared spectroscopy (NIRS) can be used to more accurately pinpoint the onset of AKI—and provide a more targeted opportunity to potentially change its course.

Identifying Biomarkers Before AKI Onset

In his earlier study, Dr. Harer found that for every four premature babies who received caffeine citrate, the onset of AKI within the first week of life was prevented in one.

That “number needed to expose” dropped to 2.2 among the most vulnerable babies—those born before 27 weeks. That means that for every two babies who receive caffeine citrate, one case of AKI was prevented. (Read the full paper in JAMA Pediatrics.)

The challenge, Dr. Harer explains, is that the biomarkers used to diagnose AKI reveal the injury 12 to 24 hours after it has already occurred. “We can’t predict who will have AKI, and by the time we detect it, it’s already happened,” he says.

He hypothesizes that a sudden drop in oxygen saturation in a premature baby’s kidney that can be detected by NIRS monitoring may be a marker of AKI onset.

So, much like pulse oximetry is used to monitor oxygen saturation of blood, he’s using NIRS to monitor oxygen saturation of kidney tissue.

His one-year study (currently underway), is enrolling up to 60 babies born before 32 weeks and admitted to the UnityPoint Health-Meriter Hospital NICU. The babies are monitored with NIRS sensors from no later than 48 hours of age until 7 days after birth, and the data analyzed to determine correlation between kidney oxygen levels and AKI markers.

Dr. Harer presented a poster with a preliminary analysis of his data at the 2018 International Symposium on AKI in Children on October 13, 2018 (see abstract on page 15 of PDF linked here).

He hopes that being able to detect AKI as it happens may lead to further research on how and when to administer caffeine citrate to mitigate its impact.

“If this improves the kidney health of babies in the NICU, it can also improve their long-term kidney function as they grow up,” he says.

Dr. Harer’s research is supported by the Department of Pediatrics and a grant from the UnityPoint Health-Meriter Foundation.