What Is Acute Kidney Injury?

Acute kidney injury (AKI) is a condition caused by a sudden decrease in kidney function within a matter of a few hours to a few days. It can be any structural damage to the kidney or impairment in function. This condition was earlier referred to as acute renal failure (ARF). This differs from chronic kidney disease in that in the chronic condition, the kidney gradually loses function over a longer timescale.

Acute kidney injury occurs mostly along with other health issues, especially in patients who are already hospitalized or in intensive care units. It makes this condition hard to identify early. Acute kidney injury causes waste products to build up in the blood, further affecting the kidneys and water balance in the body. This can also start affecting other organs, such as the brain, heart, and lungs. Hence, acute kidney injury is often seen as part of a multi-organ dysfunction.

What Causes Acute Kidney Injury?

The reason for acute kidney injury can be multifold depending on the condition of the patient. It can occur because of decreased blood flow due to low blood pressure, organ failure, etc., or direct damage to the kidneys caused by conditions like sepsis and cancer or due to blockage of the urinary tract. While previously mostly the severe cases of acute kidney injury were given importance and immediate treatment, meanwhile even a mild case of acute kidney injury has been identified to lead to severe clinical consequences. Therefore, identifying and treating mild cases has become equally important.

Depending on the trigger of acute kidney injury, the symptoms can vary, such as low urine output, swelling in the legs, shortness of breath, fatigue, nausea, diarrhea, confusion, chest pain, and others.

How Is Acute Kidney Injury Identified and Treated?

While in the short term, acute kidney injury may affect kidney and other organ functions temporarily, in the long term, it can lead to further incidences of acute kidney disease or conditions like chronic kidney disease and heart disease. Therefore, it is vital to identify the issue early and treat it. Urinary tests, blood tests to check creatine levels (a chemical waste product from the muscles), glomerular filtration rate (to test kidney function), ultrasound imaging of the kidney, and kidney biopsies are a few tests the doctors may recommend for acute kidney injury if they suspect it. The poorer the kidney function, the higher the creatine levels in the blood will be. This is one of the standards used in testing for the condition.

The cure primarily involves treating the primary cause of acute kidney injury. For example, if a blocked urinary tract is causing the condition, then the tract is cleared. If the condition occurs due to dehydration, appropriate fluids need to be given. Depending on the comorbidities, the treatment can vary and the patient may be able to fully recover from the acute kidney injury. In severe cases, dialysis might be required until the function of the kidney is restored.

If the patient is known to be at risk for acute kidney injury, then regular blood tests must be done to check for creatine levels along with being watchful of urine output and other parameters as recommended by the doctor.

Acute Kidney Injury in Pregnancy

The incidence of an acute kidney injury occurring in pregnancy was around 0.12% in the USA in 2015 and has been shown to have increased over time. The increase is partially due to better detection but also due to other factors like older age, other health complications like diabetes or history of preeclampsia, and even ethnicity.

Acute kidney injury in pregnancy is associated with a 14-fold higher chance of mortality. With two lives involved, this becomes a serious condition that needs to be better understood. There is a risk of adverse fetal outcomes including pre-term birth, low baby weight, and fetal mortality. Diagnosing acute kidney injury in pregnant women is similar to what has been mentioned earlier about non-pregnant patients. The serum creatinine level is the main test, and depending on the symptoms and suspected cause, other tests can be done. Kidney biopsies are also safe to do in the first and second trimesters. In the third trimester, depending on the fetal viability and patient’s condition, the doctor may decide to do the biopsy postpartum.

What Are the Reasons for Pregnancy-Related Acute Kidney Injury and How Can It Be Treated?

In the first trimester, acute kidney injury can be caused due to dehydration caused by pregnancy-related nausea and vomiting or due to an abortion complicated with an infection. In the former case, hydration is the treatment while in the latter case, antibiotics are used to treat the patient.

In the second trimester, there are multiple ways acute kidney injury could occur. In the case of urinary tract infections, antibiotics are administered before it leads to further complications. Acute kidney injury can also occur due to conditions like preeclampsia, which is a pregnancy complication involving high blood pressure, or Hemolysis, Elevated Liver enzymes, and Low Platelets (HELLP) syndrome. In these cases, premature delivery of the baby is the main option of treatment considered.

Thrombotic thrombocytopenic purpura, a condition of blood clots forming in small blood vessels, can lead to acute kidney injury, too. Plasma exchange or certain medications are given to treat this condition. For glomerulonephritis, a condition involving damage of the filters in the kidney, steroids and immunosuppressants are administered depending on the condition of the patient and fetus.

How Can Incidences and Complications due to Pregnancy-Related Acute Kidney Injury Be Reduced?

It is essential to create awareness among physicians of the many different causes of pregnancy-related acute kidney injury. The treatment needs to involve a multidisciplinary approach including a nephrologist, gynecologist, and neonatologist. Early diagnosis can also be improved by screening pregnant women for kidney function at the beginning of pregnancy and during any pregnancy-related hospitalization. By improving the diagnosis, treatment, and care of pregnant women, the rate of women developing or dying from acute kidney injury can be reduced.