ACUTE KIDNEY INJURY Flashcards
● Acute kidney injury is defined when one of the following criteria is met
○ Serum creatinine rises by ≥ 26 µmol/L within 48 hours or
○ Serum creatinine rises ≥ 1.5 fold from the reference value, which is known or presumed to have occurred within 7 days or
○ urine output is < 0.5ml/kg/hr for ≥ 6 consecutive hours
AKI: RISK FACTORS
● Pre-existing chronic kidney disease (CKD)
● Volume depletion
● Use of nephrotoxic agents
● Obstruction of the urinary tract
AKI ASSESSMENT
● Past Medical History
○ Renal disease-related chronic conditions
■ Hypertension, diabetes
● Medication History
● Patient symptoms
○ Change in urinary habits, sudden weight gain, flank pain, back where kidneys are situated
signs of AKI
● Signs ○ Edema (sometimes) , may have high bp ○ Coloured or foamy urine ○ Orthostatic hypotension ○ Hypertension ● Laboratory tests ● Other diagnostic tests
OTHER ASSESSMENTS OF KIDNEY FUNCTION
▪ Serum Creatinine
▪ Urea (BUN) (2.9-7.1 mmol/L)
▪ Both are elevated when acute changes in kidney function are observed
urea itself is not helpful
what are the 3 types of AKI?
- Prerenal
https: //www.osmosis.org/learn/Prerenal_azotemia - Intrarenal (Intrinsic)
https: //www.osmosis.org/learn/Renal_azotemia - Postrenal
https: //www.osmosis.org/learn/Postrenal_azotemia
PRERENAL AKI
(HEMODYNAMIC)
explain
▪Most common cause of AKI (>60% of cases)
▪Occurs over hours-days
▪Generally a result of renal hypoperfusion
▪Glomerular filtration is restored on re-establishment of more normal renal perfusion
▪*no actual structural damage or injury to the kidney itself
causes of PRERENAL AKI
Hypovolemia ▪Hemorrhage ▪GI fluid losses ▪Renal fluid losses ▪Extravascular (severe burns in body, losing extravascular fluid, hypovolemic)
Altered renal hemodynamics
▪ Low cardiac output state (heart failure)
▪ Systemic vasodilation (sepsis), decreased kid perfusion
▪ Renal vasoconstriction
▪ Impaired renal autoregulatory responses
▪ Hepatorenal syndrome (blood flow shifted away from kdineys)
PRERENAL AKI symptoms
▪ Symptoms
▪ Thirst
▪ Orthostatic hypotension
Dehydration: ▪ Tachycardia ▪ Reduced jugular venous pressure ▪ Decreased skin turgor ▪ Dry mucous membranes
PRERENAL AKI lab findings
▪ Laboratory Findings
▪ ↑ BUN; ↑ creatinine;
Urine Studies
▪ Hyaline casts ▪ FENa <1% (lower fractional exretion of Na) ▪ UNa <20 mmol/L ▪ SG >1.020
- kidneys try to preserve water, reabsorbtion along with sodium due to dehydration
POSTRENAL AKI
explain
▪caused by obstruction of urine flow at any level of
the urinary tract (ureter, bladder, urethra)
▪5 % of AKI cases
▪must occur in both kidneys at the same time
POSTRENAL AKI
causes
which drugs?
▪Physical barrier ▪ kidney stones ▪ prostate hypertrophy ▪ cancer ▪Drugs that crystallize ▪sulfonamide ▪methotrexate ▪ acyclovir
POSTRENAL AKI
symptoms
urinalysis
Pain
▪Anuria
▪Pyuria - WBCs in urine
Urinalysis
▪Cellular debris
▪Hematuria, blood in urine
INTRINSIC (INTRARENAL) AKI
explain
▪ Occurs in 25-40 % of AKI cases
▪ Acute injury to the kidney itself
▪ Nephron
▪ Either acute or chronic damage
INTRINSIC (INTRARENAL) AKI
causes
▪DRUGS ▪Other toxins ▪Ischemia ▪Infection ▪Autoimmune diseases
