Acute Kidney Injury (AKI)

____ indicates aki

changes in SCr, BUN, urine output

Nephrotoxic Medications

Reduce prostaglandin-dependent kidney blood flow, and can cause allergic interstitial nephritis (AIN) and nephrotic syndrome

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

Nephrotoxic Medications

Accumulate in proximal tubular cells, disrupting phospholipid metabolism, leading to cell apoptosis and acute tubular necrosis (ATN)

Aminoglycosides

Nephrotoxic Medications

Likely related to ATN (Acute Tubular Necrosis resulting from damage to kidney cells) and possible AIN (Acute Interstitial Nephritis kidney inflammation)

Vancomycin 

Nephrotoxic Medications

Can cause AIN, ATN, crystalluria within the distal convoluted tubule, and reversible inhibition of tubular creatinine secretion

Sulfamethoxazole-Trimethoprim (Bactrim)

Nephrotoxic Medications

AKI and CKD due to tubulointerstitial nephritis and AIN.

Proton Pump Inhibitors (PPIs) (omeprazole/pantoprazole)

Nephrotoxic Medications

Chronic use can lead to nephrogenic diabetes insipidus and chronic tubulointerstitial nephropathy

Lithium 

Additional Nephrotoxic Medications agents: Antibiotics, Antifungals, ACEIs, ARBS, Diuretics, IV Contrast, Chinese Herbal Medicine, cisplatin and methotrexate, amphotericin B, polymyxins, and tenofovir, VEGF inhibitors and bisphosphonates

These medications can cause kidney damage or worsen existing kidney conditions, leading to complications such as AKI and CKD

Patient Presenting Symptoms for AKI

• ______

Weakness, Fatigue, Mental status changes

Nausea or Vomiting or loss of appetite

Bleeding

Edema, Shortness of breath, fast heart rate

Weight gain or loss

Flank pain

Decreased urine output

Patient Findings for AKI 

Low or elevated Blood Pressure

Elevated Heart Rate

Elevated Respiratory Rate

___- more concentrated

Dark colored urine

Laboratory Findings for AKI

Serum Creatinine elevated from baseline

Blood Urea Nitrogen elevated

Serum Electrolytes (elevated potassium, decreased sodium)

Urine Electrolytes/Creatinine

use ____ as test

Kidney and Bladder Ultrasound

Urinanalysis

Urine Output

Monitor Hourly urine output

◦ Goal _____/kg/hr

Anuria <100 mL/24 hours

Oliguria <400ml/24 hours

Non-Oliguria >400 mL/24 hours

>0.5 mL

KDIGO Criteria

AKI is present if any of the following are met:

◦ Increase in Scr ____ mg/dL in 48 hours

◦ Increase in Scr ____ baseline over 7 days

◦ Urine volume ____/kg/hr in the past 6

hours

>0.3, >1.5x, <0.5

AKI Staging

• SCr: 1.5-1.9 x baseline OR ≥0.3 mg/dL increase

• Urine output: <0.5 mL/kg/hr for 6-12 hours

1

AKI Staging

• SCr: 2-2.9 x baseline

• Urine output: <0.5 mL/kg/hr for ≥12 hours

2

AKI Staging

• SCr: 3.0 x baseline OR Increase Scr ≥4 mg/dL OR Initiation of renal replacement therapy

• Urine Output: ≤0.3 mL/kg/hr for ≥ 12 hours OR Anuria for ≥ 12 hours

3

AKI Pathophysiology

• decreased renal perfusion

prerenal

AKI Pathophysiology

• direct kidney damage

intrarenal

AKI Pathophysiology

• obstruction to urinary flow

postrenal

IF urinalysis is normal, this indicated a ____ AKI

prerenal

IF urinalysis show

Granular Casts = ATN (Acute Tubular Necrosis)

◦ Crystals

◦ Myoglobin (from muscle breakdown) = Rhabdo

◦ WBC or Eosinophils = Acute Interstitial Nephritis

◦ Protein (Albumin) or Hematuria = Acute

glomerular nephritis



, this indicated a ____ AKI

intrarenal

IF urinalysis has crystals, this indicated a ____ AKI

postrenal

BUN to SCr Ratio (BCR)

BUN ÷ SCr

High (____): ____

◦ Urea re-absorption is INCREASED when low renal blood flow, while creatinine stays stable

> 20:1, pre-renal

BUN to SCr Ratio (BCR)

BUN ÷ SCr

Low (_____): ____

◦ Some debate over this

◦ < 12 indicative of acute interstitial nephritis

10-15, intra-renal or post-renal

Urine Sodium (Na)

Low (____): _____

◦ Kidneys attempt to conserve Na in response to decreased perfusion

(<20): Pre-renal

Urine Sodium (Na)

High (____): _____

◦ Damaged renal tubules lose ability to reabsorb Na effectively

> 40, Intra-renal

FENa <1% and FEUrea <35% are indicative of _____

prerenal AKI

FENa >2% and FEUrea >50% suggest _______

Intrinsic renal causes such as ATN

_____ is particularly useful in patients on

diuretics, where FENa may be less reliable

FEUrea

____: concentration expressed as the total number of solute particles per kg

Osmolality

Urine Osmolality

High (___)=_____

◦ Kidneys are still able to concentrate urine effectively in response to reduced blood flow

> 500, Pre-renal

Urine Osmolality
Low (____)=_____

◦ Due to damage kidneys lose ability to concentrate urine effectively

◦ Urine similar concentration to plasma

~300, Intrarenal

Urine Osmolality

Varies = ___

◦ Initially present with high urine osmolality if the obstruction is partial and the kidneys are still able to concentrate urine.

◦ Prolonged obstruction can lead to tubular damage and decrease in urine osmolality

Post-renal 

Pre-renal

Causes: _____

◦ Volume overload/Acute heart failure exacerbation

◦ Hypotension (sepsis), fluid loss (nausea/diarrhea/extreme exercise), blood loss (hemorrhage)

◦ Compensatory Mechanisms

◦ Activation of RAAS to release ADH leading to vasoconstriction and water and sodium retention

◦ Afferent arteriole dilation and efferent arteriole constriction

◦ Nephrotoxic medications (NSAIDS, ACEI, ARBS, Diuretics)

Decreased blood flow to the kidney

Pre renal identification

• BUN/SCR ratio

• Urinalysis

• Urine Na

• Urine Osm

• FeNa %

• FeUrea

>20, negative, <20. >500, <1, <35

Pre-Renal Treatment

• VOLUME DEPLETED=

• Discontinue or hold any offending agents

• Isotonic Crystalloids:: _____

Lactate Ringer or 0.9% NaCl

Pre-Renal Treatment

VOLUME OVERLOAD

• Discontinue or hold any offending agents

  • Loop diuretics: _____

IV furosemide (Lasix), Bumetanide (Bumex), Torsemide (Demadex) 

Loop Diuretics and Resistance

Dosing of Loop Diuretics for Volume Overload

Initiate Furosemide ______

◦ If on diuretics at home, give the same dose IV

◦ IV furosemide is 2x as potent at PO (1:2 IV:PO)

Expected onset: 20 minutes

20-40mg IV x1

Loop Diuretics and Resistance

Dosing of Loop Diuretics for Volume Overload

If no urine output in 1-2 hours, can double the IV dose.

____Furosemide = ____ PO Torsemide = ____ Bumetanide

40 mg Furosemide=20mg Torsemide=1 mg Bumetanide

Loop Diuretics and Resistance

Dosing of Loop Diuretics for Volume Overload

Max IV Push: _____

Furosemide 200mg, Bumetanide 4 mg

Resistance cont'd

Some patients experience little urine output despite large doses of loop diuretics

Change to a loop diuretic continuous infusion (lower doses per hour)

Add on thiazide diuretic: _____

Consider ______ if fluid overload from acute decompensated heart failure

Chlorthalidone PO, Chlorothiazide IV, Metolozone PO; consider acetazolamide (Diamox)

Intra-renal AKI: due to ____

• Vasculature

  • Occlusion of vessels (thromboemboli)

• Glomerulus

  • Acute Glomerulonephritis

• Tubules

  • Acute Tubular Necrosis (MOST COMMON)

• Interstitium

  • Acute Interstitial Nephritis

Damage to the Kidney 

Intra-renal Identification

Increased SCr

Decreased urine output (non-oliguria or oliguria)

main one: _____

CT of kidneys

Biopsy when indicated

Specific findings on urinalysis or labs

Acute Tubular Necrosis (ATN)

Conditions: long-standing ischemia

Medications: _____

Urine flow is obstructed by accumulation of sloughed epithelial cells, cellular debris, and

formation of casts

Antibiotics (Beta-lactams, Aminoglycosides, Vancomycin), Amphotericin B, cisplatin, Statins, Cocaine, Alcohol, Contrast Dye (usually 1-3 days after)

Pre renal identification

• BUN/SCR ratio

• Urinalysis

• Urine Na

• Urine Osm

• FeNa %

• FeUrea

10-15, granular casts, >40, 300, >2, >50

DRUGS:

Sulfamethoxazole/trimethoprim (Bactrim)

Indinavir

Atazanavir

Acyclovir

Methotrexate

can cause _____

Intrarenal Crystal Obstruction

Elevated Serum Creatine Kinase >15,000 units/mL

Dark brown urine

Causes: Overexertion, prolonged muscle injury

Drugs: Statins

Rhabdomyolysis 

Rhabdo identification

• BUN/SCR ratio

• Urinalysis

• Urine Na

• Urine Osm

• FeNa %

• FeUrea

5:1, muddy brown/myoglobin, >20, 300, >2, >50

Causes: Medications

Immune Mediated

Onset: Median is 11 days after drug start

(Range 3-20 days)

Symptoms: Fever, Rash

Urinalysis: WBC or Eosinophils

Serum eosinophils elevated, Anemia

Renal biopsy findings

Acute Interstitial Nephritis

AKA: Nephritic Syndrome

Causes: Infections, Immune disorders

Urinalysis: Hematuria or proteinuria (blood and protein in urine= foam/frothy)

◦ Cola-colored urine (blood)

Hypertension

Serum IgA levels

Renal Biopsy Findings

Acute Glomerular Nephritis

Causes: Prostatic hypertrophy, Prostate/bladder/cervical/uterine cancer, renal stones

(nephrolithiasis)

identification: Ultrasound of bladder/kidneys

CT of abdomen

Urine output (minimal)

Post Renal

Post Renal Therapy

Remove or bypass the obstruction

◦ Foley Catheter

◦ Suprapubic Catheter

◦ Lithotripsy or Stone Removal

◦ Medications: _____

Alpha-1 blockers (tamsulosin (Flomax) or alfuzosin (Uroxatral), 5a-reductase inhibitors (finasteride (Proscar)) for Prostate

Most life-threatening

Treat if:

1. K+> 6.5 mEq/L

2. Muscle weakness or paralysis OR cardiac

conduction abnormalities or arrhythmias

3. AKI PLUS K+>5.5 mEq/L PLUS tissue

breakdown (Rhabdo, crush injury, TLS) or

ongoing K absorption (ex. from GIB)

4. K+>5.5 + kidney impairment (ESKD or

oliguria)

Hyperkalemia

Treatment of Hyperkalemia

• antagonism of membrane action of potassium

calcium

Treatment of Hyperkalemia

• drive extracellular potassium into the cells

insulin and glucose, sodium bicarb, b2 adrenergic agonist

Treatment of Hyperkalemia

• removal of potassium from the body

loop/thiazide diuretics, cation exchange resin, dialysis

Hyperkalemia 

Stabilize the heart

If ECG changes are present, give ____

calcium gluconate or calcium chloride

Treatment of Hyperkalemia

• Move potassium into the cell

Insulin regular 10 units IV + Dextrose 25 g and sodium bicarbonate

Treatment of Hyperkalemia : Loop Diuretics

Evaluate hemodynamics

IV Furosemide 20-40mg or Bumetanide 1 mg

Treatment of Hyperkalemia: Potassium Binding Resins

Oral/Rectal Sodium Polystyrene (_____) (least preferred)

Oral Sodium Zirconium cyclosilicate (______) (most preferred)

Oral Patiromer (____) (second preferred)

Kayexalate, Lo-kelma, Veltessa

Acidosis

Treat when HC03- <16 mEq/L

_________ 50mEq IV (may repeat prn)

Hemofiltration if hemodynamic instability

Sodium bicarbonate

Hyperphosphotemia

Phosphorous may be elevated >5 mmol/L

No medications can lower phosphorous

◦ Dialysis typically doesn’t either

Consider ________

◦ Calcium Acetate, Calcium Carbonate, Ferric Citrate, Lanthanum, Sucroferric Oxyhydroxide

phosphate binders  

Hypocalcemia

Serum calcium usually decreases from high phosphorous

Check serum calcium vs. Ionized calcium

◦ Corrected Calcium Level (based on albumin, normal level typically 4)

◦ Ca = Serum Calcium + 0.8*(Normal albumin – patient albumin)

Replenish calcium if <7 mmol/L

◦ ______is preferred

Calcium Gluconate