540 - Examining the association between normalized protein catabolic rate and bone disease in pediatric patients on chronic hemodialysis

Publication Number: 4528.540

Ashley V. Trinh, Children's National Health System, Washington, DC, United States; Kristen Sgambat, Children's National Hospital, Washington DC, DC, United States; Anqing Zhang, Children's National Health System, D.C., DC, United States; Celina Brunson, Children's National Health System, Silver Spring, MD, United States

Background: Children receiving chronic hemodialysis (HD) are at risk for nutritional complications and mineral bone disease. While adequate dietary protein intake is essential to prevent malnutrition, excess protein can lead to increased phosphorus intake and increased acid production. Normalized protein catabolic rate (nPCR) is commonly used to assess nutritional status in HD patients and serves as a surrogate for dietary protein intake. Generally, nPCR of at least 1.0-1.2 g/kg/day is considered adequate, though an upper limit has not been established. In adult patients receiving chronic HD, both low and high nPCR scores have been associated with increased fracture risk. However, studies examining the relationship between nPCR and markers of bone health in children on chronic HD are limited.

Objective: To determine whether increased intake of dietary protein, as indicated by elevated nPCR, is associated with markers of adverse bone health in pediatric chronic HD patients and to identify at what nPCR level the adverse bone health outcomes occur.

Design/Methods: We conducted a retrospective chart review of pediatric patients ages 0-12 years receiving chronic HD for ≥5 months at an outpatient dialysis center from 2002–2023. Variables collected included nPCR, serum phosphorus, calcium, parathyroid hormone, 25-hydroxy vitamin D, and bicarbonate levels, as well as clinical documentation of bone disease which included presence of fractures and/or renal osteodystrophy. GLMM with ROC analysis was used to identify the nPCR threshold corresponding to increased risk for adverse bone health outcomes.

Results: There were 686 observations from 52 patients included in the analysis (56% male, median age 8.4 years). Hyperphosphatemia occurred in 35%, hypocalcemia in 26%, hyperparathyroidism (>300) in 52%, acidosis in 35%, and bone disease in 67%. Based on comparative model performance, nPCR ≥1.8g/kg/day was determined to be the optimal cut-point to define high nPCR (see figure, ROC AUC of 0.97 with 95% CI 0.95-0.98). High nPCR was significantly associated with hyperphosphatemia (p=0.046) and trended towards statistical significance with acidosis (p=0.056), after adjusting for all other bone health parameters.

Conclusion(s): In pediatric HD patients, protein intake ≥1.8g/kg/day may contribute to hyperphosphatemia and acidosis, adversely impacting markers of bone health. nPCR may guide nutritional management to balance adequate nutrition with avoidance of excess protein intake. Larger multicenter studies are needed to further investigate effects of excess protein intake on bone health outcomes in this population.

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