Kidney

• Acute Kidney Injury (AKI)

  Characterized by abrupt decline in kidney function => elevated serum creatinine and/or reduction in urine output
• AKI leads to an ↑ in Cr to 1.5 times (or more) baseline and low urine output
• AKI onset is sudden (hours to days), varies from mild to severe and is often reversible, but mortality is high
• Dialysis may be required for AKI
• Who is at risk for development of an AKI

  • Patients with infections
  • Patients with low blood pressure
  • Patients exposed to nephrotoxins
• Sepsis is the most common cause of AKI
• Pre-Renal AKI


  • Decrease in glomerular filtration and perfusion
  • Decrease in renal blood flow
• Intra-Renal AKI


  • Direct damage to renal tissue/tubules
  • ATN - most common in renal causes of AKI
• Post-Renal AKI


  • Mechanical obstruction of urinary outflow
• Pre-Renal AKI


  • Hypovolemia
  • Altered peripheral vascular resistance
  • Cardiac disorders
• Sudden drop in BP leads to a higher AKI risk
• Usual cause of Intra-Renal AKI is direct damage to tubules
• Causes of Intra-Renal AKI

  • Prolonged renal ischemia
  • Nephrotoxic drugs
  • Organic solvents
  • Acute hemolysis
  • Acute glomerulonephritis
• Post-Renal AKI


  • Obstruction of urine flow due to stones
  • tumors
  • enlarged prostates
  • urethral scarring or infection
• Process of pre-renal AKI

  1. Decreased blood flow

  2. Lower GFR

  3. Compensation by the RAAS

  4. Still not enough to maintain normal GFR

  5. Less urine formed

  6. Less waste product excreted
• Process of intra-renal AKI

  1. Injury of the epithelial lining of the tubules

  2. Inflammation/swelling/loss of function

  3. Cells die

  4. Collect at renal tubules

  5. Obstruct mvt of filtrate

  6. UP intratubular pressure

  7. DOWN GFR

  8. DOWN UO

  9. Azotemia
• Azotemia


  Waste products levels too high in the blood
• Post-Renal AKI Process


  1. Obstruction of outflow from kidney

  2. Intratubular pressure UP to push against obstruction

  3. DOWN GFR
• Initiation of AKI


  1. UP CR

  2. UP BUN

  3. DOWN UO
• Maintenance of AKI


  1. Lasts days to weeks

  2. Usually nonoliguric then oliguric then anuric

  3. Fluid retention and edema

  4. HTN apparent

  5. Metabolic acidosis

  6. Fluid and electrolyte imbalance

  7. Anemia

  8. Waste product accumulation
• Anuria


  Lack of urine (pee) production
• Oliguria


  Low urine output
• Recovery of AKI


  1. Return of BUN, creatinine, eGFR toward normal ranges

  2. May have diuretic phase

  3. Recovered ability to excrete waste

  4. Risk for hypovolemia and hypotension

  5. Risk for hyponatremia, hypokalemia, dehydration

  6. May take 12 months to stabilize
• Diuresis indicates leaving the maintenance stage of an ATN and entering the recovery phase
• Confusion in recovery phase may be due to hypovolemia and hypotension leading to ↓ PO4 reaching the brain
• Glomerulonephritis


  Immune-mediated inflammation of the urinary tract (primarily the glomerulus)
• Both kidneys are equally affected in Glomerulonephritis
• Causes of Glomerulonephritis


  • Drugs
  • Infection
  • Immune disorders
• Glomerulonephritis


  • Characterized by proteinuria
  • Hematuria
  • Decreased urine production
  • Oliguria
• Acute Glomerulonephritis


  • AKI
  • Acute
  • Oliguria
  • LOW GFR
• Rapidly Progressive Glomerulonephritis


  • Acute Glom that didn’t resolve leading to CKD
• Chronic Glomerulonephritis


  • Acute injury resolved but inflammation persistent
• Nephrotic Glomerulonephritis


  • Atypical
• Acute Poststreptococcal Glomerulonephritis


  • The immune attack on the strep infection causes antigen-antibody complexes to form
• Acute Poststreptococcal Glomerulonephritis most often affects children aged 3-7
• Symptoms of Acute Poststreptococcal Glomerulonephritis

  • Oliguria
  • Edema
  • Hypertension
  • Urinalysis: WBC, RBC, protein, erythrocyte casts
  • Blood work: UP Urea, UP Creatinine
• Most UTIs ascend and occur from bacteria entering the urethra
• E.coli is the most common pathogen leading to UTI
• Major defense against ascending bacteria


  • The flushing effect of urine flow
• Most at risk for UTI

  • Females
  • Any obstruction in urinary tract