Blockage of Renal Vein |

Renal vein thrombosis or kidney blood clot

Renal Vein Thrombosis refers to the blockage of the renal vein (carries oxygen-depleted blood away from the kidney) by a blood clot (thrombus).

May be mild or absent
Some patients present with shortness of breath due to a clot in the lung (i.e., pulmonary embolus).
If it occurs suddenly:

Back or flank pain (pain in the upper back to the sides)

Hematuria or Blood in the Urine

Low urine volume

Blood clots form when normally liquid blood thickens, or its flow slows down and becomes stagnant.
Causes of blood clot formation:

Trauma to back or abdomen will damage the vein or scar it, and slow the normal blood flow.
Malignant (invasive/cancer) renal tumors such as Renal Cell Carcinomas can invade the vein and cause blockage to blood flow.
External compression of the vein from pregnancy, tumors of the abdomen, or narrowing or strictures of the major vein known as the inferior vena cava.
Nephrotic Syndrome -- membranous glomerulonephropathy

Dehydration in infants

History of symptoms, illnesses, past history of thrombosis, allergies, medications, surgeries (especially abdominal or vascular), family history, and habits

Medical exam may reveal flank or back pain.

Urinalysis under a microscope may reveal red blood cells.

Blood tests may reveal high levels of kidney chemical known as LDH enzyme.

X-Ray, Ultrasound, MRI or CAT scan are radiographic techniques that can show the size (often enlarged kidney), structure, and clot location in the kidneys.

Venography, done by injecting a dye (coloring) into the veins and then X-Raying the area, can show the location of the renal vein narrowing or clotting.

See causes
Problems with substances that alter blood viscosity (fluidity):

Platelet abnormalities

Increased Fibrinogen levels

Decreased Antithrombin III

Protein C and S deficiency

Anticardiolipin syndrome

Oral contraceptives

Estrogen therapy

Thrombophlebitis migrans

Hydration with intravenous fluids may help.

Thinning the blood first with heparin (intravenously) and then orally with warfarin pills, which may need to be continued.

Surgical removal of the clot (thrombectomy), removal of the infarcted kidney (nephrectomy), or inserting a flexible tube to reopen the blocked vein (recanalization) are other options.