Prevalence and Risk Factors of Proteinuria in Pediatric Heart Transplantation.

PURPOSE: Renal dysfunction is a common complication of heart transplantation (HTx) in children that affects overall outcome. Proteinuria reflects renal glomerular and tubular damage and is an early marker of renal dysfunction, even when excreted in small amounts, termed microalbuminuria. The prevalence of microalbuminuria in pediatric HTx has not been previously described. We report the prevalence of proteinuria as measured by microabuminuria to creatinine ratio (UACR) and its associated risk factors in pediatric HTx recipients.

METHODS: Since 2015, UACR is collected annually at rejection surveillance catheterization. Patients aged <21 years with at least one UACR were identified. Patients with dual heart/kidney transplant retransplantation, and presence of diabetes pre-transplant were excluded.

RESULTS: 116 patients were identified, of whom 51 (44%) were female and 68 (58%) Caucasian. Mean age at HTx was 5.4 ± 6.2 years. Ninety-two (79%) were listed status 1A, and 74 (64%) had congenital heart disease. Perioperative therapies included mechanical circulatory support in 23 (20%), dialysis in 4 (3%), mechanical ventilation in 34 (29%). No patients had insulin dependent diabetes pre-HTx and 2 (2%) developed diabetes in the first year post-HTx. Mean pre-HTx eGFR was 99 ± 35.5 ml/min/1.73m2 . At a latest follow-up of 5.8 ± 3.8 years, 7 (6%) patients developed diabetes, 42% (n=35) had an abnormal UACR (≥ 31 units). Mean UACR was 85 ± 182.5 and 25% had eGFR <60 ml/min/1.73m2 . Using univariate regression adjusted for time from HTx, younger age at HTx was protective against abnormal UACR (RR 0.94, p <0.05) and post-HTx dialysis was associated with abnormal UACR (R 3.1, p<0.001).Development of diabetes in the first year post-txp was associated with abnormal UACR (β -80, p=0.001).

CONCLUSION: Microalbuminuria as a marker of renal injury is a highly prevalent finding in medium-term follow up of pediatric HTx. Post-Htx dialysis and diabetes is a risk factor for developing microalbuminuria and younger age at transplant may be protective. These observations may have implications on early identification of chronic renal disease and its medical intervention.