Review Question - QID 107160

This woman has renal vein thrombosis secondary to nephrotic syndrome. In nephrotic syndrome, urinary loss of anticoagulant proteins, such as antithrombin III, predisposes the patient to thrombosis.

Nephrotic syndrome occurs when large quantities of protein are lost in the urine. The most prominent physical exam finding is generalized edema (anasarca). The pathogenesis of the disorder is related to the loss of albumin and other proteins into the urine, which decreases the serum oncotic pressure. Accordingly, the Starling forces in vascular capillary beds change to favor loss of fluid into the extravascular space, leading to edema. There are several recognized variants of nephrotic syndrome, which include focal segmental glomerulosclerosis, membranous nephropathy, and minimal change disease.

Kodner reviews the possible complications associated with nephrotic syndrome. Progressive weight gain and edema are the typical presenting symptoms, but other complications may be caused by loss of specific proteins in the urine. Loss of antibodies can predispose to infection. Loss of endogenous anticoagulant molecules, especially antithrombin III, can predispose to thrombosis, manifesting as DVT, PE, or renal vein thrombosis (as in this vignette).

Kerlin et al. discuss the management of thromboembolism in nephrotic syndrome. Prophylaxis in patients without thromboembolism is controversial. However, once a thromboembolism has formed, management is similar to that used for non-nephrotic syndrome patients. Of note, heparin may be less effective in patients with severe antithrombin III loss, as heparin is dependent on antithrombin III for exerting its full effect. Warfarin is generally the preferred long-term anticoagulant in affected patients.

Illustration A is a CT scan showing thrombosis of the right renal vein.

Incorrect Answers:
Answer 1: Severe dehydration can cause renal vein thrombosis in neonates.
Answer 3: Hepatic synthetic failure can cause edema through the loss of albumin; however, the patient's urinary finding of over 10 grams of protein per day suggests renal, not hepatic, etiology.
Answer 4: Oral contraceptive pills can cause thrombosis such as a DVT, but they are very rarely linked to renal vein thrombosis.
Answer 5: Hereditary factor VIII deficiency (Hemophilia A) is an X-linked recessive disorder, which would predispose the patient to bleeding, not clotting.