Abstract 16754: Bone Mineral Density is Abnormal in Children with Protein Losing Enteropathy Following the Fontan Procedure

Abstract

BACKGROUND: Protein losing enteropathy (PLE) is a rare but potentially devastating complication of single ventricle physiology following the Fontan operation. Pathological spinal compression fractures have been observed clinically in children with PLE but there are no reports of bone mineral density (BMD), vitamin D [25(OH)D)], or calcium metabolism in this population. OBJECTIVE: To describe abnormalities in BMD in a cross section of children with single ventricle physiology complicated by PLE following the Fontan operation. METHODS: Cross-sectional sample of children and young adults with a confirmed diagnosis of PLE. Serum levels of 25(OH)D, calcium, total protein, and albumin were recorded from the first outpatient encounter of each subject at The Single Ventricle Survivorship Program at The Children's Hospital of Philadelphia. Corrected calcium (cCa) was calculated from the serum calcium and albumin levels. BMD was measured using dual energy X-ray absorptiometry (DXA), and Z-scores were generated using appropriate software. RESULTS: DXA results were available for evaluation in 12 patients (8M/4F). Age at DXA ranged from 7.2 - 25.2 years. The mean Z-score was -1.73 SD for the entire cohort, 42% below -2 SDs. Serum 25(OH)D levels were abnormal in 58%. Mean serum calcium level was 8.6 ± 0.6 mg/dL, mean serum total protein was 5.1 ± 1.1 g/dL, mean serum albumin was 2.9 ± 0.8 g/dL, and mean cCa was 9.4 ± 0.4 g/dL. Of those on chronic corticosteroid therapy, the mean DXA Z-score was -3.15 SD, 67% below -2 SDs. There was a positive correlation between cCa and DXA Z-score and a negative correlation between total protein and DXA Z-score. Patients on corticosteroid therapy had a significantly lower DXA Z-score than those not on corticosteroids (-3.15 vs. -0.31, p=0.02). CONCLUSION: Children with PLE are at risk for abnormal BMD compared to age- and sex-matched controls. There are a number of factors that may contribute to abnormal BMD including corticosteroid use, chronic illness, and protein loss through the enteric mucosa. In this cohort, corticosteroid therapy, a marker of chronic disease, appeared to be associated with decreased BMD. Routine bone health screening is warranted for children with PLE, particularly those receiving corticosteroid therapy.