In renal cortical necrosis, which may be patchy or diffuse, bilateral renal arteriolar injury results in destruction of cortical tissues and acute kidney injury Acute Kidney Injury (AKI) Acute kidney injury is a rapid decrease in renal function over days to weeks, causing an accumulation of nitrogenous products in the blood (azotemia) with or without reduction in amount of urine... read more . Renal cortical tissues eventually calcify. The juxtamedullary cortex, medulla, and the area just under the capsule are spared.
Etiology of Renal Cortical Necrosis
Injury usually results from reduced renal artery perfusion secondary to vascular spasm, microvascular injury, or intravascular coagulation.
About 10% of cases occur in infants and children. Pregnancy complications increase risk of this disorder in neonates and in women, as does sepsis. Other causes (eg, disseminated intravascular coagulation [DIC] Disseminated Intravascular Coagulation (DIC) Disseminated intravascular coagulation (DIC) involves abnormal, excessive generation of thrombin and fibrin in the circulating blood. During the process, increased platelet aggregation and coagulation... read more ) are less common (see table Causes of Renal Cortical Necrosis Causes of Renal Cortical Necrosis ).
Symptoms and Signs of Renal Cortical Necrosis
Gross hematuria, flank pain, and sometimes decreased urine output or abrupt anuria occur. Fever is common, and chronic kidney disease with hypertension develops. However, these symptoms are often overshadowed by symptoms of the underlying disorder.
Diagnosis of Renal Cortical Necrosis
Imaging, usually with CT angiography
Diagnosis is suspected when typical symptoms occur in patients with a potential cause.
Imaging tests can sometimes confirm the diagnosis. CT angiography CT angiography CT shows a focal area of osteolysis (arrows) involving the right acetabulum that is consistent with particle disease. In CT, an x-ray source and x-ray detector housed in a doughnut-shaped assembly... read more is usually preferred despite the risks of using an iodinated contrast agent. Because of the risk of nephrogenic systemic fibrosis, use of magnetic resonance angiography with gadolinium contrast is not recommended in these patients, who usually have severe renal dysfunction.
An alternative is isotopic renal scanning using diethylenetriamine penta-acetic acid. It shows enlarged, nonobstructed kidneys, with little or no renal blood flow. Renal biopsy is done only if the diagnosis is unclear and no contraindications exist. It provides definitive diagnosis and prognostic information.
Urinalysis, complete blood count (CBC), serum electrolytes, liver tests, and renal function tests are done routinely. These tests often confirm renal dysfunction (eg, indicated by elevated creatinine and blood urea nitrogen and by hyperkalemia) and may suggest a cause. Severe electrolyte abnormalities may be present depending on the cause (eg, hyperkalemia Hyperkalemia Hyperkalemia is a serum potassium concentration > 5.5 mEq/L (> 5.5 mmol/L), usually resulting from decreased renal potassium excretion or abnormal movement of potassium out of cells. There are... read more , hyperphosphatemia Hyperphosphatemia Hyperphosphatemia is a serum phosphate concentration > 4.5 mg/dL (> 1.46 mmol/L). Causes include chronic kidney disease, hypoparathyroidism, and metabolic or respiratory acidosis. Clinical features... read more , hypocalcemia Hypocalcemia Hypocalcemia is a total serum calcium concentration 8.8 mg/dL ( 2.20 mmol/L) in the presence of normal plasma protein concentrations or a serum ionized calcium concentration 4.7 mg/dL ( 1.17... read more ). CBC often detects leukocytosis (even when sepsis is not the cause) and may detect anemia and thrombocytopenia if hemolysis Overview of Hemolytic Anemia At the end of their normal life span (about 120 days), red blood cells (RBCs) are removed from the circulation. Hemolysis is defined as premature destruction and hence a shortened RBC life span... read more , disseminated intravascular coagulation Disseminated Intravascular Coagulation (DIC) Disseminated intravascular coagulation (DIC) involves abnormal, excessive generation of thrombin and fibrin in the circulating blood. During the process, increased platelet aggregation and coagulation... read more (DIC), or sepsis is the cause. Transaminases may be increased in relative hypovolemic states (eg, septic shock Sepsis and Septic Shock Sepsis is a clinical syndrome of life-threatening organ dysfunction caused by a dysregulated response to infection. In septic shock, there is critical reduction in tissue perfusion; acute failure... read more , postpartum hemorrhage Postpartum Hemorrhage Postpartum hemorrhage is blood loss of > 1000 mL or blood loss accompanied by symptoms or signs of hypovolemia within 24 hours of birth. Diagnosis is clinical. Treatment depends on etiology... read more ). If DIC is suspected, coagulation studies are done. They may detect low fibrinogen levels, increased fibrin-degradation products, and increasing prothrombin time (PT)/INR and partial thromboplastin time (PTT). Urinalysis typically detects proteinuria and hematuria.
Prognosis for Renal Cortical Necrosis
Prognosis of renal cortical necrosis was poor in the past, with mortality > 50% in the first year. More recently, with aggressive supportive therapy, 1-year mortality can be about 20%, and up to 20% of survivors may recover some renal function.
Treatment of Renal Cortical Necrosis
Treatment is directed at the underlying disorder and at preserving renal function (eg, with early dialysis).
Renal cortical necrosis is rare, typically occurring in neonates and in pregnant or postpartum women with sepsis or pregnancy complications.
Suspect the diagnosis in patients at risk who develop typical symptoms (eg, gross hematuria, flank pain, decreased urine output, fever, hypertension).
Confirm the diagnosis with renal vascular imaging, usually CT angiography.
Treat the underlying disorder.