Current Pediatric Reviews - Volume 9, Issue 3, 2013

Nephrotic syndrome is comprised of massive proteinuria in association with hypoalbuminemia, hyperlipidemia, and edema. Thromboembolism is an important source of morbidity and mortality in nephrotic syndrome and virtually any location may be affected. This review focuses on the epidemiology, pathophysiology, clinical features, and diagnosis of thromboembolism in pediatric nephrotic syndrome.

Neonatal renal vein thrombosis (NRVT) is a complication that occurs in newborns with various underlying risk factors. Various modes of therapies, including anticoagulation and fibrinolytic therapies have been reported with anecdotal success. Due to a lack of prospective controlled trials, there is currently no evidence-based guideline available for the treatment of neonates with renal vein thrombosis. The clinical features, diagnosis and current approach to management of neonatal renal vein thrombosis are reviewed in this chapter.

New evidence shows that patients with chronic kidney diseases are prone to develop thromboembolism. In this chapter, current knowledge of risk factors associated with thrombotic events, as well as practical approaches to anticoagulation in this population are discussed.

Thrombotic thrombocytopenic purpura (TTP) is a rare pediatric disease, yet has grave outcome if not managed properly. It shares many common clinical features with hemolytic uremic syndrome (HUS). While it is still disputable whether TTP and HUS are clinically related disorders, recent studies indicate that severe deficiency of a von Willebrand factor (vWF) cleaving protease is one of the primary causes of TTP. In this discussion, we will focus on TTP in reference to the deficiency of this protease, with the objective of increasing awareness among pediatric healthcare professionals of this less commonly recognized disease.

Renal allograft thrombosis is the leading cause of graft failure in pediatric transplant recipients in the early post-transplant period. Various factors at multiple levels- donor, recipient, surgical and therapy-related, come into play in contributing to this risk. While early detection and intervention are keys in limiting the adverse effect of graft thrombosis on graft survival, preventative strategies have the most to offer in reducing morbidity related to this devastating complication. This article reviews the epidemiology, risk factors, diagnostic and therapeutic modalities to assist the clinician in taking care of children who are in the process of receiving renal transplants. The authors also address various strategies to screen for and prevent thromboses in this population. Lastly, we identify gaps in our knowledge base related to allograft thrombosis, to bridge which, robust research is urgently needed.

Renal thrombosis has multiple potential causes and a variety of imaging techniques can be used to make the diagnosis. Hypercoagulable states, ranging from hereditary thrombophilia to dehydration, may result in thrombosis in previously healthy renal veins. Abnormal vasculature, including a spectrum of primary vascular disorders, such as stenosis or vasculitis, may result in arterial or venous thrombosis. Traumatic injury to the vascular pedicle or dissection may also cause thrombosis. Renal vein thrombosis is an uncommon but potentially serious condition that may result in acute complications such as pulmonary embolus and acute renal failure, or may lead to chronic kidney disease and hypertension. Until relatively recently, RVT could only be confidently confirmed or excluded with selective renal venography, however ultrasound is now the imaging method of choice for neonatal and pediatric RVT [1-4]. A spectrum of grey-scale, and Doppler imaging features has been described for the acute and late phases of the condition. Some authors have reported specific sonographic features that might predict poor outcome and renal atrophy [4, 5]. Magnetic resonance imaging provides accurate diagnostic evaluation of renal vasculature, particularly in the assessment of renal masses, but is typically reserved for those cases where the Doppler findings are inconclusive. In general, computed tomography (CT) diagnostic yield is comparable to magnetic resonance imaging (MRI). The requirement for IV contrast and significant radiation dose should be balanced against the potential need for general anaesthesia as well as institutional availability and expertise.

Renal vein thrombosis (RVT) is a common type of venous thrombosis in neonates. The reported incidence in literature is 2.2 per 100,000 live births in Germany [1]. In Canada, the number of live births is an estimated 350,000 per year [2]; a 10-year review reports an annual incidence of 2.3 cases of RVT [3]. RVT in children and adults is so rare that the exact incidence is unknown. However, physicians managing such patients need to be aware that both the risk factors and their clinical courses may be different among patients of different age groups. For a comprehensive review of the epidemiology, pathophysiology, etiology, presentation, and diagnosis of RVT, readers are referred to other chapters in this special issue. The present chapter focuses on the management of this disease.

This article provides the pediatric clinician with brief discussions and summaries of the various commonly used, and published, anticoagulation agents and strategies currently used by centers offering renal replacement therapy to children and adults. Pediatric data and references are provided when they exist; adult literature is reviewed and summarized when and where pediatric data are lacking. The coagulation system in general, its alterations in the face of the “uremic milieu”, and the biologic effects of the extracorporeal system (namely dialyzer membranes and tubing) on the coagulation cascade are reviewed. Anticoagulation strategies for continuous and intermittent hemodialytic methods and peritoneal dialysis are reviewed, followed by a discussion of patients at elevated risk of bleeding and heparin induced thrombocytopenia. The doses and protocols are reviewed and presented here as they have been previously published in journals or textbooks; however, every patient and clinical situation is unique and any decision to make use of the strategies outlined in this paper should be made by the treating physician with careful consideration of the individual patient risk and benefit.