The aim of this study is to determine whether the sarcopenia index (SI) is a viable measure of muscle mass in pediatric patients with brain tumors.
Retrospectively enrolled patients (1-16 years) who had serum creatinine (Cr) and cystatin C (CysC) levels evaluated within 28 days of an abdomen magnetic resonance imaging scan for the lumbar vertebrae 3-4 total psoas muscle area (tPMA) were studied. Variables were compared using their z scores calculated from age- and sex-dependent reference. We hypothesized that a low SI indicated less skeletal muscle, and therefore potentially indicated sarcopenia.
The SI z score had no correlation with tPMA z score (r = 0.004). Both Cr and CysC levels were positively correlated with tPMA in z scores (r = 0.249 and 0.320). tPMA strongly correlated with body mass index in z scores (r = 0.582). The z scores of tPMA, Cr and CysC decreased with elevated World Health Organization grades of tumor, but the z scores of SI showed no significant dependence on WHO grades.
The correlation of SI to muscle mass is very weak in our sample of pediatric patients with brain tumor. Its viability as biomarker for sarcopenia needs more study.

© 2023 American Society for Parenteral and Enteral Nutrition.