Renal vein thrombosis and response to therapy in a newborn due to protein C deficiency

Thrombosis in the critically ill neonate: incidence, diagnosis, and management

Among children, newborn infants are most vulnerable to development of thrombosis and serious thromboembolic complications. Amongst newborns, those neonates who are critically ill, both term and preterm, are at greatest risk for developing symptomatic thromboembolic disease. The most important risk factors are inflammation, DIC, impaired liver function, fluctuations in cardiac output, and congenital heart disease, as well as exogenous risk factors such as central venous or arterial catheters. In most clinically symptomatic infants, diagnosis is made by ultrasound, venography, or CT or MRI angiograms. However, clinically asymptomatic vessel thrombosis is sometimes picked up by screening investigations or during routine imaging for other indications. Acute management of thrombosis and thromboembolism comprises a variety of approaches, including simple observation, treatment with unfractionated or low molecular weight heparin, as well as more aggressive interventions such as thrombolytic therapy or catheter-directed revascularization. Long-term follow-up is dependent on the underlying diagnosis. In the majority of infants, stabilization of the patients’ general condition and hemodynamics, which allows removal of indwelling catheters, renders long-term anticoagulation superfluous. Nevertheless, in certain types of congenital heart disease or inherited thrombophilia, long-term prophylaxis may be warranted. This review article focuses on pathophysiology, diagnosis, and acute and long-term management of thrombosis in critically ill term and preterm neonates.

A neonate with homozygous protein C deficiency with a homozygous Arg178Trp mutation

Homozygous protein C deficiency affects approximately 1/400,000 to 1/1,000,000 live births. Homozygous protein C deficiency is associated with catastrophic and fatal purpura fulminans-like or thrombotic complications and disseminated intravascular coagulation. In the present patient, genetic study revealed Arg178Trp, a mutation found widely in European population; but this is the first case of homozygous Arg178Trp mutation who suffered from catastrophic purpura fulminans phenotype.

Catheter-directed thrombolysis of inferior vena cava thrombosis in a 13-day-old neonate and review of literature

Complete inferior vena cava thrombosis (IVC) in neonates is uncommon, but may cause significant morbidity. A 13-day-old neonate suffered IVC thrombosis secondary to antithrombin III deficiency, possibly contributed to by a mutation in the methyl tetrahydrofolate reductase gene. Catheter-directed thrombolysis (CDT) with recombinant tissue plasminogen activator (rt-PA, Alteplase) was used successfully to treat extensive venous thrombosis in this neonate without complications. We also review the literature on CDT for treatment of IVC thrombosis in critically ill neonates and infants.

Renal outcome of neonatal renal venous thrombosis: review of 28 patients and effectiveness of fibrinolytics and heparin in 10 patients

OBJECTIVES

Neonatal renal venous thrombosis is a rare disorder that can result in severe renal damage. To evaluate the experience over 10 years and review the effectiveness of fibrinolytic and/or heparin therapy, chart reviews were performed for newborns with renal venous thrombosis. PATIENTS, INTERVENTIONS, AND OUTCOME MEASURES: Twenty-eight newborns with renal venous thrombosis were treated at Children's Hospitals and Clinics of Minnesota and Fairview University Medical Center from 1991 to 2001.

RESULTS

Unilateral involvement was noted in 25 neonates (89%) and bilateral involvement in 3 (11%). Unilateral renal venous thrombosis affected mostly term infants, whereas 2 of 3 infants with bilateral renal venous thrombosis were <32 weeks' gestational age (birth weight: 745-1505 g). One mother had antiphospholipid syndrome. Of 11 neonates evaluated for congenital thrombophilia, 1 had the factor V Leiden mutation. Ten neonates received either unfractionated or low molecular weight heparin for 3 days to 7 months. Three infants with unilateral renal venous thrombosis treated with heparin alone did not seem to benefit from such therapy. Seven neonates were treated with fibrinolytics and unfractionated heparin (4 neonates with unilateral renal venous thrombosis and 3 with bilateral renal venous thrombosis). Treatment with fibrinolytics did not result in restoration of renal function in the 4 neonates with unilateral renal venous thrombosis but was associated with return of almost normal function in the 2 neonates with bilateral renal venous thrombosis who received fibrinolytics immediately after renal venous thrombosis diagnosis. Two neonates treated with fibrinolytics suffered bleeding complications at the area of adrenal hemorrhage. Two neonates (not treated for renal venous thrombosis) died as a result of underlying disease.

CONCLUSIONS

Most neonatal renal venous thrombosis is unilateral and does not respond to fibrinolytic therapy and heparin. The use of fibrinolytics may prevent chronic renal failure in neonates with bilateral renal venous thrombosis if begun within 24 hours of diagnosis. Fibrinolytic therapy, however, is associated with a risk of bleeding, specifically if there is an associated adrenal hemorrhage.

Neonatal renal venous thrombosis: clinical outcomes and prevalence of prothrombotic disorders

OBJECTIVE

To determine clinical outcomes and the prevalence of prothrombotic conditions in patients who had neonatal renal venous thrombosis (RVT).

STUDY DESIGN

A retrospective cohort of neonates with RVT who were admitted to 4 pediatric centers from 1980 to 2001 was identified. Information on clinical presentation, laboratory and radiological investigation, and treatment were abstracted. Survivors were evaluated for renal status and prothrombotic conditions.

RESULTS

Forty-three patients with neonatal RVT were identified. RVT was unilateral in 24 patients (56%) and associated with 2thrombi at other sites in 32 patienets (74%). Clinical presentations included renal failure in 24 patients (56%), thrombocytopenia, anemia, or both in 22 patients (51%), and renal mass in 21 patients (49%). Neonatal interventions included anti-coagulants in 28 patients (65%), antihypertensive medications in 9 patients (21%), peritoneal dialysis in 2 patients (5%), and nephrectomy in 2 patients (5%). The median age at follow-up was 3.7 years (range, 0.5-20.2 years). Thirteen patients (34%) had hypertension, and 11 patients (29%) had renal failure. End-stage renal disease developed in 3 patients, and they underwent live-related renal transplants. Twelve of the 28 patients (43%) examined had prothrombotic abnormalities.

CONCLUSION

Neonatal RVT is associated with significant renal morbidity and a high prevalence of prothrombotic abnormalities.

Acute renal vein thrombosis, oral contraceptive use, and hyperhomocysteinemia

Oral contraceptive use and hyperhomocysteinemia are considered to be relatively weak risk factors for venous thromboembolism. We report a case of acute renal vein thrombosis, a rare and aggressive form of thromboembolism, that occurred in a 21-year-old woman taking oral contraceptives, who was subsequently found to have marked hyperhomocysteinemia. This case suggests that the oral contraceptive and hyperhomocysteinemia may interact in a synergistic manner in the pathogenesis of thrombosis. In oral contraceptive users who develop venous thrombosis in the absence of other risk factors, clinicians should consider investigations for an underlying prothrombotic biochemical disorder.

Evaluation and treatment of thrombosis in the neonatal intensive care unit

Thromboses are infrequent but serious complications of patients in the NICU. Thromboses tend to occur in very sick neonates, particularly preterm neonates, and the majority of such thromboses are related to central vascular catheters. Other risk factors for neonatal thromboses include infants of diabetic mothers, sepsis, small for gestational age, congenital heart disease, maternal antiphospholipid syndrome, and possibly inherited prothrombotic disorders. Appropriate treatment, dosage, and duration of therapy for neonatal thromboses has not been studied in clinical trials. Treatment options include observation, anticoagulation, thrombolysis, and surgical thrombectomy. Regardless of the treatment chosen, all neonates with thromboses require frequent reassessment of the thromboses by angiography, echocardiography, or ultrasound until thrombus resolution occurs.

Correlation between the functional assay for activated protein C resistance and factor V Leiden in the neonate

A factor V506 Arg-Gln mutation is the most common inherited cause of thrombophilia in adults. To date, there are no data regarding the detection of this mutation in neonatal blood or the relationship of this dysfunctional factor V to neonatal thrombosis. This study compared a modified activated protein C resistance functional assay with the PCR-based DNA assay for the factor V mutation in 115 prospectively collected umbilical cord blood samples. The incidence of activated protein C resistance in cord blood was 6%. The sensitivity and specificity of the modified assay for the factor V Leiden mutation was 100%.

Hemostatic complications in renal disorders of the young

This review focuses on the hemorrhagic and thrombotic complications sometimes associated with the most common renal disorders in children. A Medline search of the literature was conducted from 1966 to January 1995, using combinations of key words appropriate for each disorder. Additional references were located through the bibliographies of the publications and recent journals were searched independently. The most common renal disorders with hemostatic complications in children were: renal vein thrombosis (268 children in 80 publications), hemolytic uremic syndrome (473 children in 29 publications), nephrotic syndrome (4,158 children in 51 publications), renal transplantation (3,976 children in 14 publications), glomerulonephritis (20 publications), end-stage renal disease, and dialysis (22 publications). The age distribution, clinical presentation, etiology, diagnosis, treatment, and outcome of the affected children were analyzed for each disorder. Children with inherited pre-thrombotic disorders usually do not present during childhood unless there is a secondary risk factor. Similarly, most children with renal disease do not develop thromboembolic complications. Therefore, when a child with a renal disorder develops a thromboembolic event, evaluation for an inherited pre-thrombotic disorder should be seriously considered. Guidelines for the use of heparin and warfarin in these children (both therapeutically and prophylactically) are given. At this time, the risk/benefit of thrombolytic therapy in children is not known and a general recommendation for thrombolytic therapy cannot be made.

Choline inhibition of prothrombin activation

A computer-interfaced spectrophotometric kinetic assay for prothrombin activation was developed, coupling the production of thrombin to a thrombin-specific amidolytic chromogenic reaction. As thrombin accumulated initially at constant velocity, the simultaneous release from S-2238 of pNA conformed to an acceleration function. Adherence to the acceleration function of the temporally increasing A400 of pNA was evaluated after transforming the data into linear format which permitted linear regression analysis. High correlation coefficients, routinely greater than 0.99, verified linearity of thrombin production in individual assay mixtures. As prothrombin concentrations were varied, factor Xa exhibited Michaelis-Menten kinetics. Added choline produced a pattern of mixed-type inhibition. Replots of LB slopes and intercepts versus choline concentration gave apparent Ki and Ki' values (mM): 22 +/- 3 and 48 +/- 7 without factor Va, 25 +/- 4 and 41 +/- 4 with factor Va.