Renal Vein Thrombosis

Renal Vein Thrombosis 

Definition

Renal vein thrombosis develops when a blood clot forms in the renal vein, which carries blood from the kidneys back to the heart. The disorder is not common.

Description

Renal vein thrombosis occurs in both infants and adults. Onset of the disorder can be rapid (acute) or gradual. The number of people who suffer from renal vein thrombosis is difficult to determine, as many people do not show symptoms, and the disorder is diagnosed only by specific tests. Ninety percent of childhood cases occur in children under one year old, and 75% occur in infants under one month of age. In adult women, oral contraceptive use increases the risk of renal vein thrombosis.

Causes and symptoms

In children, renal vein thrombosis almost always occurs rapidly after an episode of severe dehydration. Severe dehydration decreases blood volume and causes the blood to clot more readily.

In adults, renal vein thrombosis can be caused by injury to the abdomen or back, as a result of malignant kidney tumors growing into the renal vein, or as a result of kidney diseases that cause degenerative changes in the cells of the renal tubules (nephrotic syndrome).

Acute onset of renal vein thrombosis at any age causes pain in the lower back and side, fever, bloody urine, decreased urine output, and sometimes kidney failure. In adults, when the onset of the disorder is gradual, there is a slow decrease in kidney function, and protein appears in the urine. Many adults with renal vein thrombosis show few symptoms.

Diagnosis

Renal venography, where a contrast material (dye) is injected into the renal vein before x rays are taken, is one of the best ways to detect renal vein thrombosis. Other useful tests to detect a clot include computed tomography scans (CT scans), magnetic resonance imaging (MRI), and ultrasound.

Treatment

One of the major goals of treatment is to prevent the blood clot in the renal vein from detaching and moving into the lungs, where it can cause serious complications as a pulmonary embolism. The enzyme streptokinase may be given to help dissolve the renal clot. Anticoagulant medications are usually prescribed to prevent clots from recurring. Rarely, when there is a complete blockage of the renal vein in infants, the kidney must be surgically removed.

Prognosis

Most cases of renal vein thrombosis resolve without any permanent damage. Death from renal vein thrombosis is rare, and is often caused by the blood clot detaching and lodging in the heart or lungs.

Prevention

There is no specific prevention for renal vein thrombosis. Preventing dehydration reduces the risk that it will occur.

Resources

Organizations

National Kidney Foundation. 30 East 33rd St., New York, NY 10016. (800) 622-9010.http://www.kidney.org.

Other

"Renal Vein Thrombosis." HealthAnswers.com. 〈http://www.healthanswers.com/database/ami/converted/ooo513.html〉.

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renal

pertaining to the kidney. See also kidney.

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renal abscess

results from infected emboli and infarcts. Usually without localizing signs unless they are very large and palpable, or when they extend into the renal pelvis and cause pyelonephritis.

renal adenoma

rare, incidental necropsy finding.

renal agenesis

failure of the renal tissue to develop; unilateral agenesis causes compensatory hypertrophy in the single kidney; bilateral is fatal. Commonly accompanies genital tract malformation.

renal artery

see Table 9.

avian renal hemorrhage

sporadic unexplained disease of turkeys; sudden death is common.

renal biopsy

is conducted usually with a biopsy needle introduced percutaneously through the flank. In food animals it is possible to fix the left kidney via a rectal manipulation, but the right kidney can be impossible to reach.

renal calculus

see urolithiasis.

renal capsular cyst

see feline perirenal cysts.

renal carcinoma

commonest in old male dogs. They are very large, spread locally and metastasize widely.

renal casts

see urinary cast.

renal clearance tests

laboratory tests that determine the ability of the kidney to remove certain substances from the blood. See also phenolsulfonphthalein clearance test, inulin clearance.

renal cortical fissures

external fissures created by the lobar structure of the large ruminant kidney.

renal cortical hypoplasia

see renal dysplasia (below).

renal cortical necrosis

results from patchy or complete renal ischemia and is part of the terminal state of many diseases, e.g. severe metritis, grain overload in cattle, azoturia in horses.

renal countercurrent system

see countercurrent.

renal cyst

incidental necropsy finding except for polycystic kidney disease. See also feline perirenal cysts.

renal cystadenoma

inherited as an autosomal dominant trait in middle-aged German shepherd bitches with generalized nodular dermatofibrosis.

renal diabetes insipidus

see nephrogenic diabetes insipidus.

renal dialysis

the application of the principles of dialysis for treatment of renal failure (below). See also hemodialysis and peritoneal dialysis.

renal diverticuli

diverticuli of the renal pelvis.

renal dysfunction

reduced capacity to excrete metabolic products which accumulate systemically and are detectable clinicopathologically by renal function tests. The early stage of uremia.

renal dysplasia

small, misshapen kidneys at birth. May be caused by intrauterine infection of the fetus by virus, but numerous inherited renal dysplasias occur in dogs. They occur in several breeds and are manifested by signs of chronic renal insufficiency, e.g. polyuria, polydypsia, poor growth and weight gain, pale mucous membranes, and renal secondary osteodystrophia fibrosa, from an early age.

renal ectopia

see pelvic kidney, horseshoe kidney.

renal erythropoietic factor

erythropoietin.

renal failure

inability of the kidney to maintain normal function. Impairment of kidney function affects most of the body's systems because of its important role in maintaining fluid balance, regulating the electrochemical composition of body fluids, providing constant protection against acid-base imbalance, and controlling blood pressure. See also kidney.

renal function tests

include blood urea nitrogen and serum creatinine estimations, tests of concentrating ability, tests of ability to excrete test substances, e.g. phenolsulfonphthalein (PSP) clearance test. Of the urine tests, only specific gravity (SG) has any significance in terms of a function test but abnormalities of urine should lead to a function test being conducted.

renal hilus

a fissure on the medial border of the kidney through which arteries, veins and ureter enter.

renal hypophosphatemic rickets

inherited as an X-linked dominant trait in children and mice; characterized by hypophosphatemia and normocalcemia due to failure of phosphate resorption in renal tubules, and skeletal deformities. Called also vitamin-resistant rickets.

renal infarct

results from embolic or thrombotic occlusion of renal arteries or branches. Clinical signs are those of renal colic initially followed by toxemia if the infarct is infected.

renal insufficiency

see renal dysfunction (above).

renal ischemia

a significant cause of renal dysfunction and cortical and medullary necrosis. Is usually part of a general state of shock, dehydration and severe toxemia.

renal lobe

a large mass of a kidney, comprising the tissue contributing to each pyramid; kidneys may be unilobar (unipyramidal), e.g. cats, dogs, small ruminants, horses, or multilobar (multipyramidal), e.g. cattle, pigs.

renal lobule

small masses of kidney tissue comprising a medullary ray and its associated nephrons.

renal medullary necrosis

necrosis of the renal medulla due to restriction of blood flow in medullary vessels, usually due to venous occlusion.

renal medullary washout

see medullary solute washout.

renal mineralization

see nephrocalcinosis.

renal osteodystrophy, renal osteitis fibrosa, renal osteitis fibrosa cystica

see renal secondary hyperparathyroidism.

renal oxalosis

deposition of oxalate crystals in renal tubules of patients poisoned by dietary oxalate, usually in poisonous plants.

renal papillae

see renal papilla.

renal papillary necrosis

necrosis of renal papillae due usually to obstruction to urinary flow or poisoning or dehydration.

renal pelvis

the chamber in the kidney into which the collecting tubules discharge urine and from which urine is voided into the ureter.

renal plasma flow

the effective rate of blood flow through the kidneys; the determining factor relative to the rate of glomerular filtration.

renal portal system

a system unique to birds; half to two thirds of the blood supply to the kidney comes from the hindlimbs via veins and terminates in peritubular capillaries where it is mixed with arteriolar blood coming from the glomeruli.

renal rickets

see renal secondary hyperparathyroidism.

renal shutdown

cessation of the excretory function of the kidney; oliguria.

renal spongiform encephalopathy

spongiform encephalopathy associated with renal failure.

renal tubular casts

see urinary cast.

renal vein thrombosis

commonly associated with renal amyloidosis in dogs.