Explain the pathophysiology of acute renal failure. Include prerenal, intrarenal, and postrenal causes. According to Mayo Clinic staff (2012), acute kidney failure occurs suddenly when your kidneys lose their filtering capabilities and cannot filter waste from your blood. This is also known as acute kidney failure or acute kidney injury. When this happens, high levels of waste can build up in your blood and change the chemical composition of your blood, throwing it out of balance. This breakdown or injury can occur quickly within a few hours or days and become fatal. Most people hospitalized and seriously ill will need intensive care. If you take care of your body, acute kidney failure can be reversible and you can return to normal kidney function. Prerenal renal insufficiency can be any condition that reduces renal perfusion and results in decreased glomerular filtration rate. If prerenal is identified and treated correctly, it can be reversible. Some conditions that may contribute to prerenal renal failure are: fluid shifts related and secondary to burns, hypertension, and reduced cardiac output in patients with congestive heart failure. If the primary cause continues to affect renal perfusion, this can lead to ischemic damage to the nephrons (Ludwig, Mathews, Gregg 2012). The causes of intrarenal renal failure are actual damage to nephrons and kidney tissue functions. These conditions could be grouped under kidney disease or acute tubular necrosis. ATN may be reversible, but it may take weeks or months before adequate perfusion returns (Ludwig, Mathews, Gregg 2012). Postrenal renal failure is caused by obstruction of urinary flow or excretion. Common problems would be tumors, benign prostatic hyperplasia (BPH) or kidney stones. Intrarenal insufficiency and nephron damage could occur if left untreated (Ludwig, Mathews, Gregg 2012). What diagnostic tests would be used to diagnose acute renal failure? How do these tests change as kidney failure progresses through its 3 stages? Discuss, compare and contrast the 3 steps. To better understand your patient's particular case of acute kidney injury, you will want to collect your patient's history to see if they have used nephrotoxic medications or had any systemic illnesses in the past that might have been related. to poor perfusion in their body. Lab tests you would want to pay attention to would be a complete blood count, urinalysis, ultrasound, glomerular filtration rate, and measurement of serum creatinine and potassium levels (Rahman, Shad, Smith 2012).