Acute Kidney Injury (AKI), the formerly Acute Renal Failure or ARF

Notes

## Basic introduction:

  • AKI is defined as an acute or subacute decline in the glomerular filtration rate and/or tubular function that is characterized by azotemia
  • It is an abrupt loss of renal function that develops within a period of about 7 days

## Causes of AKI:

  • Pre-renal AKI (is responsible for more than 90% of AKI): diuretic therapy; burns; diarrhea; vomiting; heart failure; pancreatitis; liver disease with ascites; and peritonitis
  • Diseases of renal arteries and veins: dissecting aortic aneurysm; and trauma to renal vessels
  • Intrinsic renal causes -

_Glomerulonephritis: nephritogenic strain of β-hemolytic streptococci; drug toxicity such as gentamycin, methicillin, and NSAIDS among other

_Acute interstitial nephritis: Drugs such as NSAIDs, infections; autoimmune diseases.

_Acute tubular necrosis: prolonged ischemia; volume depletion; toxins

_Intratubular obstruction: rhabdomyolysis; uric acid neuropathy

  • Post renal (mainly obstruction of collection system): bladder outlet obstruction (mainly by tumors); bilateral ureteral obstruction; ureteral obstruction in single kidney; calculus; pelvic malignancy; retroperitoneal fibrosis; urethral stricture, prostatic hypertrophy or malignancy; papillary necrosis and radiation fibrosis.
  • Eclampsia

## Risk factors for AKI:

  • Hypovolemia
  • Co-morbidity with chronic kidney disease (CKD), heart failure, diabetes, liver disease etc.
  • Sepsis
  • Past history of AKI
  • Old age (65yrs and above)
  • Use of renal toxic drugs such as aminoglycosides, ACE inhibitors, ARB, diuretics and NSAIDS
  • Peri-operative period
  • Recent use of iodinated contrast agents
Symptoms
  • It can be asymptomatic and sometimes with microscopic hematuria
  • Hematuria
  • Proteinuria
  • Edema
  • Brown/pink and foaming urine
  • Back pain
  • Abdomen or frank pain (that may indicate obstruction to urine flow or inflammation of the kidneys)
  • Headache
  • Visual disturbances
  • Vomiting
  • Convulsions
  • Azotemia (elevated BUN & Creatinine levels)
  • Coma
  • Encephalopathy
  • Oliguria or even anuria
  • Hypertension
  • Hyperkalemia
  • Acidosis
  • Heart failure
Diagnosis
  • Clinical review
  • Urinalysis, culture and sensitivity
  • Blood Urea, Creatinine & Electrolyte
  • FBC
  • Throat and/skin swab (for streptococcus)
  • Renal ultrasound
  • Antistreptolysin O titer
  • Renal biopsy (not always)
  • Additional tests to ascertain whether urinary tract is blocked or not are X-ray, CT scan, and MRI
Differential
  • Renal cancer
  • Bladder cancer
  • Pre- or post-renal failure
  • Nephrolithiasis
Prevention
  • Prevention depends on the type of AKI
  • Identify and mitigate the risk factor(s)
  • To closely monitor ALL acutely ill patients in hospital for AKI
Management
  • Management depends on the cause AKI
  • Controlled fluid replacement e.g. in diarrhea and burns
  • Avoid the use of drugs with renal toxic effects such as gentamycin, sulphonamides, tetracycline and nitrofurantoin among others
  • Administer Furosemide 1-5mg/kg if the patient is not dehydrated ,and the blood pressure is normal or high
  • Dialysis is or may be required

Manage hyperkalemia (see “Hyperkalemia” in this publication for details)

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