Approximately half of the patients admitted to the ICU develop kidney injury. This is usually because of reduced blood supply to the kidneys. Our kidneys require 20-25% of blood pumped by the heart. This amounts to approximately 1200 ml per minute of blood flow. If and when this supply falls short, our kidneys can become damaged.

Any damage to the kidneys which has occurred recently, within a week, is called acute kidney injury (AKI). If this persists for up to 3 months, it is called acute kidney disease(AKD). Other reasons for AKI may include infection, certain medicines (especially some painkillers), toxins or obstruction to the outflow of urine.

Medical terminologies aside, it is important to understand that when a kidney has been damaged in a short period of time, it may be reversible, sometimes completely and other times partially. But, till the time these kidneys heal, we nephrologists need to take care of the balance in the internal environment.

The concentrations of some chemicals such as sodium and potassium may be abnormal. The acid-base balance could be off. There could be excess fluid accumulation sometimes and other times, there may be dehydration. All this is on top of the increased amounts of waste products in the body.

Thus, sometimes, to support the human body and give the kidneys time to heal, we may offer dialysis- a technique of removing waste products from blood by the use of an external filter in a machine. However, this dialysis is mostly temporary and is stopped when the kidneys heal.

After recovery from AKI, a patient should stay in touch with their kidney doctor and get their blood and urine tests done regularly to assess the presence of residual injury.

Next, we will discuss kidney disease that persists for more than 3 months or CKD in short.