Non-invasive Method Could Help Detect Low-grade Inflammation, Study Suggests

Measuring how electricity moves through the body could help detect low-grade inflammation in adults with Prader-Willi syndrome (PWS) without the need for a blood sample, a new study suggests.

This non-invasive method could make it easier to detect increased inflammation — which has been linked to heart disease — in patients who have communication difficulties, the researchers said.

Published in the journal Nutrients, the study is titled “Phase Angle: Could Be an Easy Tool to Detect Low-Grade Systemic Inflammation in Adults Affected by Prader–Willi Syndrome?”

One of the hallmark features of obesity is chronic low-grade inflammation (LGI) — that is, increased levels of inflammatory molecules throughout the body. Because LGI is associated with an increased risk of heart disease and metabolic conditions, monitoring inflammation can be important in obesity-related conditions such as PWS.

Typically, LGI is evaluated by measuring levels of inflammatory markers in a blood sample. However, it can be difficult to obtain blood samples from people with PWS due to communication impediments. As such, methods of measuring LGI that do not rely on blood samples could be of clinical utility.

Here, researchers at the Federico II University Medical School of Naples, in Italy, tested whether the phase angle (PhA) parameter could be used to evaluate inflammation without a blood sample. PhA is a metric that can be obtained from bioelectrical impedance analysis, which involves measuring how a weak electrical current moves through the body. Generally, a lower PhA is indicative of cell death or disruptions to the cell membrane.

A total of 15 adults with PWS — six men and nine women, with an average age of 28 — were recruited for the study. For comparison, the researchers also recruited 15 adults without PWS (controls), who were matched to the PWS group in terms of age, sex, and body mass index (BMI).

In addition to measuring PhA, the researchers collected blood samples and measured the participants’ levels of C-reactive protein (CRP), a marker of inflammation.

Mean PhA values were significantly lower in the PWS group than in the control group (4.5 vs. 5.6 degrees). In turn, levels of CRP were significantly higher in the PWS patients than in those without the disease (3.5 vs. 2.2 nanograms/mL).

The scientists then conducted statistical analyses to look for associations between PhA values and CRP levels. These models accounted for other variables, including sex, BMI, and waist circumference.

The results showed that lower PhA values are associated with higher CRP levels. In other words, the findings indicate that low PhA values are indicative of more inflammation.

“The main finding of this research is the negative correlation between PhA and hs [high-sensitivity]-CRP levels in PWS adults which allows nutritionists and clinicians to evaluate LGI without the need of a blood sample,” the researchers wrote.

The scientists noted that, among other limitations, their study was designed to detect correlation, not causation. As such, it is impossible to conclude that inflammation causes PhA to drop. Rather, the data show that the two values are statistically associated, the researchers said.

In addition, the number of participants in this study was relatively small. Studies assessing other biomarkers of inflammation are required, the investigators said.

“As possible translational applications, these findings suggest that the identification of a specific cut-off value for PhA might help in identifying PWS adults at high risk of LGI who could benefit from a more detailed clinical evaluation,” the investigators concluded. “Since PWS adults have poor compliance due to their psychiatric disorders and most of the time is difficult to collect blood sampling, making the biochemical diagnosis of LGI not always possible, PhA could be a potential useful noninvasive biomarker of LGI, meeting the unmet needs in this population.”