Elevated blood creatinine is not always caused by nephritis disease. Blood creatinine represents kidney function, so when blood creatinine is elevated it indicates renal failure. In addition to renal causes, renal failure can also have pre-renal and post-renal factors. Pre-renal factors refer to the decrease in blood volume of the body due to any cause, which causes renal failure. Common causes include cardiac causes, such as heart failure, myocardial infarction and malignant arrhythmia; hepatic causes, such as severe hypoproteinemia due to cirrhosis of the liver, and the decrease in body volume due to vomiting, diarrhea and gastrointestinal bleeding. Post-renal factors are often manifested as obstruction of the urinary system, resulting in obstructive nephropathy.