VASCULAR CAUSES OF ACUTE KIDNEY FAILURE

Specific causes of acute kidney failure

▪   Prerenal failure and acute tubular necrosis
▪   Vascular causes of acute kidney failure
▪   Nephrotoxic causes of acute kidney failure
▪   Glomerulonephritic and vasculitic causes of
    acute kidney failure
▪   Interstitial nephritis as a cause of acute
    kidney failure
▪   'Haematological' causes of acute kidney failure
▪   Hepatokidney Syndrome
▪   Tropical

Vascular causes of acute kidney failure

• Acute cortical necrosis

• Large-vessel obstruction

• Small-vessel obstruction

Large-vessel obstruction

Arterial obstruction

Occlusion of the main kidney arteries or of the artery supplying a solitary functioning kidney by trauma, dissection, thrombosis, or embolism may rarely be the reason for acute renal failure. Loin pain sometimes occurs, and there is usually a low-grade fever, such that the clinical picture may mimic acute pyelonephritis, but symptoms can be notable by their absence. Proteinuria and haematuria may occur.

Diagnosis is important because thrombolysis and/or renovascular surgery can be surprisingly effective in restoring function, even when undertaken a considerable time after arterial occlusion (up to many weeks), in those with atherosclerotic renovascular disease in whom (prior to occlusion) a collateral blood supply to the kidney parenchyma has developed. Suspicion should be aroused by complete, sudden anuria in the absence of urinary obstruction, especially if the clinical setting is appropriate, for example atrial fibrillation in an arteriopath. A useful pointer to the diagnosis is the finding of a urinary sodium concentration similar to that of plasma, but DTPA renography and kidney angiography are the appropriate diagnostic tests if the diagnosis of kidney artery occlusion is suspected. CT scanning may reveal wedge-shaped infarcts when occlusion is incomplete.

Venous obstruction

Kidney vein thrombosis can cause acute kidney failure, most commonly in adults as a complication of the nephrotic syndrome, but in infants and children as a result of abdominal sepsis or severe dehydration. Kidney pain is common, as is increasing proteinuria and haematuria (which can be macroscopic), but there may be no symptoms. If there is clinical suspicion of the diagnosis, for example unexplained deterioration of renal function in a nephrotic patient, then appropriate investigation includes ultrasound/Doppler examination of the kidney veins and inferior vena cava, CT/MRI scanning, or kidney arteriography with late films taken specifically to look for filling of the kidney veins. Treatment by anticoagulation is the usual practice.