Why is the risk for thromboembolic complications (TEC) increased in patients with pediatric nephrotic syndrome?

Updated: Mar 04, 2020
  • Author: Jerome C Lane, MD; Chief Editor: Craig B Langman, MD  more...
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Patients with nephrotic syndrome are at increased risk for thrombosis. The incidence of thromboembolic complications (TEC) is about 25% in adults with nephrotic syndrome.

The risk of TEC varies with the underlying disease. The incidence of TEC in infants with congenital nephrotic syndrome is about 10%. The risk of thrombosis increases throughout childhood, and adolescents are at higher risk than younger children after the first year of life. The risk of TEC also is greater in secondary than in primary nephrotic syndrome. Children with membranous nephropathy and nephrotic syndrome are at high risk for TEC, with an incidence of approximately 25%. [34] Zaffanello and Franchini found the subclinical rate of pulmonary embolism in children with nephrotic syndrome to be 28% using scintigraphic pulmonary ventilation and perfusion studies. [35]

The risk of TEC is greatest earlier in the course of nephrotic syndrome. The median time from diagnosis of nephrotic syndrome to TEC was 70 days in one study. Other studies have shown that the majority of TEC occur within the first 3 months of diagnosis. [34]

Renal vein thrombosis, deep vein thrombosis, and pulmonary embolism (PE) are the most frequently encountered TEC in children. Other venous sites of thrombosis include the superior sagittal sinus, other cerebral venous sites, and the inferior vena cava.

Arterial thrombosis, although less common than venous TEC, can occur and has been reported at the axillary, subclavian, femoral, coronary, and mesenteric arteries. [36]

Nephrotic syndrome is a hypercoagulable state. The increased risk of thrombosis can be attributed to 2 basic mechanisms: (1) urinary losses of antithrombotic proteins and (2) increased synthesis of prothrombotic factors. [37]

Decreased antithrombotic factors include the following:

  • Antithrombin III

  • Proteins C and S (conflicting data)

Increased synthesis of prothrombotic factors include the following:

  • Increased platelet number, activation, and aggregation

  • Elevation in levels of factors V and VIII, von Willebrand factor, α2-plasmin inhibitor, plasminogen activator inhibitor 1, and fibrinogen

  • Increased activities of tissue plasminogen activator and plasminogen activator inhibitor-1

These abnormalities in hemostatic factors, combined with potential hypovolemia, immobility, and increased incidence of infection, lead to a hypercoagulable state in INS. [1, 38]

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