Kidney Week

Abstract: PO2318

Cyanotic Nephropathy (CN) in Pre-Fontan Congenital Cyanotic Heart Disease (CCHD) with Solitary Kidney

Session Information

• Pediatric Nephrology: Benign Urology, AKI, Neonatal Nephrology, and Case Reports
  October 22, 2020 | Location: On-Demand
  Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Report

• 1700 Pediatric Nephrology

Authors

• Vuong, Kimmy Thien, Rady Children's Hospital San Diego, San Diego, California, United States

Kimmy Thien Vuong,

• Shayan, Katayoon, Rady Children's Hospital San Diego, San Diego, California, United States

Katayoon Shayan,

• Carter, Caitlin E., Rady Children's Hospital San Diego, San Diego, California, United States

Caitlin E. Carter,

Introduction

CN is a glomerulopathy seen in patients with CCHD. Chronic hypoxia leads to proteinuria and reduced GFR through tubular and glomerular injury.

Case Description

10 yo male with single kidney and pre-Fontan CCHD presented with hematuria and proteinuria on cardiac transplant evaluation. He had 6 months of symptomatic hypoxia requiring increased supplemental O2, but no other recent illness. Exam was notable for 3/6 pansystolic murmur, tachypnea with clear lung fields, hepatosplenomegaly, cyanotic nailbeds with marked clubbing, but no peripheral edema. 24 hour urine protein measured 4.1g (normal < 0.2g), 38% was albumin. Serum albumin was 3.5 g/L (normal) and eGFR by Cystatin C was 72 ml/min/1.73m². Hemoglobin was elevated at 20.1 (normal 12.5-16.1 g/dL). C3, C4, ANA, dsDNA, ANCA were normal. Ultrasound showed solitary left kidney with nephromegaly (12.5cm, 100th%ile) and dampened diastolic flow. MRI abdomen showed dilatation of the left renal vein and IVC. Renal biopsy showed marked glomerular enlargement, segmental mesangiolysis with erythrocytolysis, and irregular thickening of glomerular capillaries. EM showed widespread subendothelial widening and remodeling of basement membranes without immune deposits, consistent with CN (Figure 1).

Discussion

CN risk factors include duration of hypoxia, elevated hematocrit >40%, and thrombocytopenia. All were present in our patient. Solitary kidney and elevated venous pressure may have contributed. After heart transplantation, renal function improved with most recent eGFR by Cystatin C 121 ml/min/1.73m². Treatment and prevention of CN depend on correction of cyanosis. CN has become less common as most children with CCHD undergo Fontan in early childhood. There are limited data about medical management but proposed treatments include renin angiotensin system blockade, beta blocking drugs, diuretics, ivabradine, digoxin, and hydralazine/isosorbde dinitrate. Therapeutic phlebotomy has been reported. To our knowledge this is the first report of CN in a patient with solitary kidney. Low renal mass and baseline glomerular hyperfiltration may increase the risk of CN progression in this subset of patients.