Introduction: Well known complications of children with intestinal failure (IF) on home parenteral nutrition (HPN) include sepsis, central access loss, liver disease, pulmonary embolism, metabolic disturbances and bone disease. Renal abnormalities are less understood. Estimation of glomerular filtration rate (eGFR) from serum creatinine, height and a proportionality constant (Schwartz Formula) is the current gold standard in children¹. Cystatin C (CysC) is freely filtered by the glomerulus, reabsorbed by tubular epithelial cells and measured in serum². The aim of this study was to investigate the incidence of renal disease (RD) comparing eGFR and CysC.

Methods: Children receiving HPN ˃ two years were identified from a tertiary IF clinic and data recorded prospectively from 2017 to 2018.Underlying IF aetiology, duration and proportion of PN were recorded. CysC was measured and eGFR calculated in 2017 and 2018. Normal renal function was defined as CysC < 1 mg/L or eGFR > 90 ml/min/1.73 m².

Results: The underlying IF diagnosis was short bowel syndrome in 15/45, enteropathy in 8/45, motility disorder in 14/45, 6/45 were post bone marrow transplantation and 2/45 had Crohn’s disease. 24/45 patients received HPN for 2-5 years and 21/45 for 5-10 years, 4/45 were weaned off PN, 4/45 were on total PN. In 2017 26/45 children had a normal CysC compared to 36/45 with normal eGFR, 19/45 (42%) had an abnormal CysC compared to 9/45 (20 %) with abnormal eGFR. In 2018 30/45 patients had a normal CysC compared to 40/45 with normal eGFR, 15/45 (33 %) had an abnormal CysC compared to 5/45 (11 %) with abnormal eGFR.

Conclusion: RD is associated with HPN. A higher proportion of RD is diagnosed by CysC compared to eGFR (p = 0.02/2017; p = 0.006/2018).

References:

1.Schwartz GJ, Work DF. Measurement and estimation of GFR in children and adolescents. J AM Soc Nephrol 2009; 4: 1832-1864

2. Roos JF, Doust J, Tett SE, Kirkpatrick CM. Diagnostic accuracy of cystatin C compared to serum creatinine estimation of renal function in adults and children – a meta analysis. Clin Biochem 2007; 40: 383-391