Cortical Necrosis
Cortical necrosis is tissue death that results from blockage of the small arteries that supply blood to the outer part of kidney (cortex) and causes acute kidney failure.
Cortical necrosis can occur at any age. About 10% of the cases occur in infants and children. More than half of the newborns with this condition had deliveries complicated by premature detachment of the placenta; the next most common cause is a bacterial infection of the bloodstream (sepsis). In children, cortical necrosis may follow an infection, dehydration, shock, or the hemolytic-uremic syndrome (see Section 14, Chapter 173).
In adults, sepsis causes one third of all cases of cortical necrosis. About half of the reported cases in women follow complications of pregnancy, such as premature detachment of or abnormal position of the placenta, bleeding from the uterus, infections immediately after childbirth, blockage of arteries by amniotic fluid, death of the fetus within the uterus, and preeclampsia.
Other causes of cortical necrosis in adults include rejection of a transplanted kidney, burns, inflammation of the pancreas, injury, snakebite, and poisoning from certain chemicals.
Symptoms and Diagnosis
The urine often becomes red or dark brown because of the presence of blood. Pain along both sides of the lower back may occur. A fever is often present. Changes in blood pressure, including mildly high pressure or even low pressure, are common.
Doctors may have difficulty making a diagnosis of cortical necrosis because it may resemble other types of acute kidney failure. A doctor may suspect cortical necrosis when the flow of urine suddenly greatly decreases or stops completely in a person who has a predisposing condition.
Blood tests may reveal an increase in the number of white blood cells and abnormally shaped red blood cells circulating in the blood. Blood tests may also reveal an increase in the levels of substances typically released when kidney tissue is damaged, such as the enzyme lactic dehydrogenase. The small amount of urine that is produced contains protein and many white and red blood cells, along with kidney cells and other debris.
Initially the kidneys may appear enlarged on ultrasound and then shrink to about half of the normal size after 6 to 8 weeks. Calcium deposits seen on x-rays suggest cortical necrosis, but these deposits are found in only 20 to 50% of people. A doctor can usually confirm the diagnosis by performing a computed tomography (CT) scan. Kidney biopsy and arteriography give important information but are invasive and are not used in most people.
Treatment
Treatment is often complicated, because the underlying condition must be treated. Kidney failure requires dialysis, although 20 to 40% of people recover partially and regain enough kidney function to discontinue dialysis after several months. For most people with cortical necrosis, however, kidney transplantation or lifelong dialysis is the only solution.
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