hello in today's video we're going to be discussing acute kidney injury what it is how it's diagnosed some common causes and general treatment options acute kidney injury is a reduction of renal function following an insult to the kidney renal function is measured through the glomerular filtration rate therefore in an acute kidney injury there is reduction to the glomerular filtration rate a lower gfr means that less blood is being filtered by the kidneys this explains why in acute kidney injuries that serum creatinine rises and patients have a reduced urine output creatinine is a byproduct of creatine metabolism in muscles it is released into the blood where it travels to the kidneys to be removed under normal circumstances with healthy functioning kidneys levels of serum creatinine remain constant as there is balance between the release of creatinine from the muscles and the rate of removal from the kidneys with an aki there is now an imbalance between the rate of creatinine production from muscle metabolism and the rate of creatinine removal from the kidney as the kidney cannot remove creatinine at the same rate serum creatinine levels begin to rise let's take a look at the nice guidelines regarding acute kidney injury an aki can be diagnosed when either serum creatinine rises by over 26 micromoles per liter or more within a 48-hour period or when serum creatinine rises more than 50 from a patient's baseline within seven days so if a patient had a stable creatinine level of 120 micromoles per liter a rise to 180 micromoles per liter would be considered an aki an aki can also be diagnosed if a patient's urine output falls to less than 0.5 mils per kilo per hour for more than 6 hours so for a patient weighing 70 kilos if they output less than 35 mils of urine per hour for at least six hours then this also indicates an aki risk factors for developing akis include advanced age underlying kidney disease such as chronic kidney disease or polycystic kidney disease diabetes ongoing illness or those who have had recent surgery and those who are taking nephrotoxic medication such as non-steroidal anti-inflammatories or ace inhibitors the causes of acute kidney injuries are categorized into three main groups and they're named according to their location of insult there are pre-renal causes intra-renal causes and post-renal causes let's take a look at these one at a time pre-renal causes are those that decrease the amount of blood flow to the kidney if less blood reaches the kidneys then glomerular filtration rate will fall as there's less blood available to be filtered by the kidneys common pre-renal causes of aki's include hypovolemia which may be caused by blood loss or dehydration through vomiting diarrhea or insufficient fluid intake low blood pressure heart failure or renal artery stenosis intra-renal or intrinsic causes of akis are those that directly damage the kidney itself the damage can be to any part of the kidney such as the glomerulus the kidney tubules or the interstitium common intra-renal causes include acute tubular necrosis or glomerulonephritis aside from these pathological conditions causing damage it is important to remember that nephrotoxic compounds can also cause damage to the kidney tubules and cause an intra-renal aki these nephrotoxins include the previously mentioned non-steroidal anti-inflammatory drugs and ace inhibitors it's also important to remember that iodinated contrast which is the contrast used for patients having a ct is also nephrotoxic therefore patients in hospital who have undergone a ct should be monitored closely for signs of an aki post-renal acute kidney injury is a result of pathology downstream from the kidneys this means anywhere from the ureters leaving the kidney to the urethra leaving the bladder post renal akis are most often caused by a blockage which consequently leads to back pressure up to the kidneys this back pressure reduces the glomerular filtration rate potential blockages or obstructions include benign prostate hyperplasia prostate cancer kidney stones or a blocked catheter in situ management for a pre-renal aki primarily focuses on fluid resuscitation to correct the volume depletion increasing the fluid volume will increase the blood flow to the kidneys and therefore can reverse the aki treatment for intrarenal aki is dependent on the underlying pathology as specific therapies are advised for inflammatory conditions such as glomerulonephritis they often respond well to corticosteroids whereas nephrotoxin-induced aki can be resolved by removal of the offending medication post-renal acute kidney injuries are remedied by bypassing the obstruction this can be achieved through either a urinary catheter or viranephrostomy which is an artificial opening between the kidney and the skin which allows urine to bypass the bladder thanks very much for watching if you're interested in finding out more about the kidney then please do watch my other videos