Nephrotic syndrome is associated with an acquired hypercoagulopathy, which in turn is associated with an increased risk of renal vein thrombosis (and VTE). What are the mechanisms underlying this propensity?
Two design features may contribute to hypercoagulopathy in the renal vein under normal circumstances:
1) The Hct in the renal vein is higher compared with the renal artery owing to fluid loss across the glomerulus (Kocatepe Vet J (2008) 1: 19-23)…… the resulting increased viscosity might lead to reduced blood flow in the renal vein.
2) The renal vein may contain valve(s), which could result in stasis of flow (PMID: 417593).
3) The nephrotic syndrome is associated with potential loss of hemostatic factors in the urine.
4) Urinary loss of antithrombin (AT) resulting in acquired AT deficiency has often been proposed as a key mechanism underlying nephrotic syndrome (NS) hypercoagulopathy. However, a recent meta analysis found only a limited mechanistic role for AT deficiency in this setting.
5) The mechanisms underlying the acquired hypercoagulopathy of nephrotic syndrome remain largely unknown!