Acute kidney Injury Flashcards
What is acute kidney injury?
- clinical syndrome manifested by a rapid or abrupt decline in kidney function and subsequent dysregulation of the body electrolytes and volume, and retention of nitrogenous wastes
- Improving Global Outcome (KDIGO) definition of AKI is based on the change of serum creatinine and urine output
Rise in serum creatinine ≥0.3 mg/dL within 48 hours
Rise in serum creatinine ≥1.5 times baseline, which is known or presumed to have occurred within the prior seven days
Urine output < 0.5 mL/kg/hour for six hours
Define acute kidney injury (AKI)
- Abrupt loss of kidney function
- Retention of urea and other nitrogenous wastes
- Dysregulation of extracellular volume and electrolytes
Explain the significance of creatinine, blood urea nitrogen, oliguria, and anuria
Creatinine - product of breakdown of creatinine phosphate by muscle tissue, filtered completely by the kidney and not metabolized - used as a marker for kidney function, inversely proportional to the function
Blood Urea Nitrogen - BUN - produced by the liver after breakdown of protein, filtered by the kidney and used as an additional measure of kidney function, high BUN means lower filtration (can increase independently of kidney function)
oliguria - <500mL of urine / 24 hr period
anuria - <100 mL of urine / 24 hr period
Describe the staging system for AKIs
Stages for staging AKI - look at absolute creatinine, changes in serum creatinine, reduction in urine output
Stage 1 -
Creatinine levels: increase in creatinine >0.3 mg/dL or 1.5-2 times from baseline
Urine output: <0.5 mL/kg/h for >6hr
Stage 2 -
Creatinine levels: increase by 2-3 times from baseline
Urine output: <0.5 mL/kg/h for >12hr
Stage 3 -
Creatinine levels: increased 3-4 times from baseline or >4mg /dL with acute increase 0.5 mg/dL
Urine output: <0.3 mL/kg/h for 24h or anuria for 12h
Identify the 3 categories of AKI
- Prerenal - volume depletion, decreased effective arterial blood volume
- Renal - tubulointerstitial disease (acute tubular necrosis, acute interstitial nephritis, acute tubular obstruction), vascular disease, glomerular disease
- Post renal - urinary obstruction
Which category of acute kidney injury is a kidney stone most likely to cause?
Post renal
To prevent acute kidney injury, treatment is ideally started at which of the following time points?
When damage is initiated
Patient A: Weight: 100 kg (220.5 lb); creatinine level increased from 1.1–2.3 mg/dL; total urine output over 14 hours: 600 mL… is this acute kidney injury stage 2?
yes
Patient C presents to the emergency department after a motor vehicle collision. Surgery is performed for splenic laceration, with an estimated blood loss of 1,500 mL. On postoperative day 1, the patient has newly elevated creatinine and BUN levels…. is this renal, postrenal, or prerenal injury?
prerenal
is this renal, postrenal, or prerenal injury?
Patient A presents to the clinic for a routine evaluation with a complaint of fatigue. There is a history of spinal cord injury causing urinary retention, and creatinine and BUN levels are chronically elevated.
renal
Patient D presents to the clinic for a routine evaluation. The patient is training for a 10 km run and has been using 2,000 mg paracetamol daily for 4 weeks to help with soreness. Creatinine and BUN levels are chronically elevated…. is this renal, postrenal, or prerenal injury?
renal
Patient B presents to the endocrine clinic for a diabetes check-up. A recent HbA1c value was 10.4%, and the patient is noncompliant with insulin use. Creatinine and BUN levels are chronically elevated…is this renal, postrenal, or prerenal injury?
renal
Identify the 2 major causes of renal hypoperfusion
- ## true volume depletion
Identify the structure of a glomerulus
- Afferent arteriole
- Efferent arteriole
- ## Glomerulus
Explain the pathophysiology of prerenal acute kidney injury
- Afferent arteriole dilates
- Efferent arteriole constricts - Angiotensin II
When on NSAIDs or ARBs -this compensatory mechanism cannot occur (in the presence of hypovolemia)
