Acute Kidney Injury

Question 1

Definition of AKI

Answer 1

Abrupt loss of kidney function that results in the retention of BUN, creatinine, and metabolic wastes normally excreted (Replaces acute renal insufficiency)

Question 2

Classification of AKI & UOP: Anuric

Answer 2

<50mL urine/24 hours
-Patients with CKD, shock, bilateral urinary tract obstruction, bilateral renal artery obstruction

Question 3

Classification of AKI & UOP: Oliguric

Answer 3

-<500mL/24 hours
-More likely to have acute tubular necrosis

Question 4

Classification of AKI & UOP: Non-oliguric

Answer 4

> 500ml/24 hours

Question 5

AKI Hx & ROS

Answer 5

-Fatigue, infectious symptoms
-oral/nasal ulcers, vision changes
-edema, weight gain/loss, HF hx, recent hypotension, chest pain
-SOB, Cough, sputum production
-intake amount, n/v, appetite, diarrhea, liver disease hx
-urine color, output amount, dysuria, stone hx, urgency/hesitancy, frequency
-Itching
-cramping, myalgia, arthralgia, trauma
-Confusion, asterixis, mental status changes, LOC changes, headaches, seizures
-Anemia, bleeding
–Rashes, fevers.
-Ask about any new OTC and prescribed meds?
-Any contrast administration?
-any chronic comorbid conditions-DM, HTN, stones, recurrent UTIs, vascular disease, cancer?

Question 6

AKI Physical Exam

Answer 6

-Htn or HOtn
-ulcerations: ent
-Elevated JVP, S3 or S4 sounds, pericardial friction rub, peripheral edema
-Crackles, signs of pleural effusions, o2 requirements, pink frothy sputum
-ascites
-enlarged prostate, bladder distention,
-Rashes, poor skin turgor, itch marks,
-cramping, weakness
-asterixis, altered LOC,
-signs of bleeding, petechial rash

Question 7

Prerenal AKI

Answer 7

-Sudden and severe drop in BP (shock), or interruption of blood flow to the kidneys from severe injury or illness

Question 8

Intrarenal AKI

Answer 8

Direct damage to the kidneys by inflammation, toxins, drugs, infection, or reduced blood supply
-Medication induced (abx, nsaids, PPI)-fever, rash, athralgia, hematuria-allergic interstitial nephritis
-ATN
-Acute glomerulonephritis

Question 9

Post renal AKI

Answer 9

-Sudden obstruction of urine flow due to enlarged prostate, kidney stones, bladder, tumor, or injury

Question 10

Types of acute renal failure

Answer 10

-ATN-Leading
-prerenal
-Acute renal failure, chronic renal failure
-Urinary tract obstruction
-glomerulonephritis or vasculitis
-atheroemboli
-acute interstitial nephritis

Question 11

Acute Tubular Necrosis

Answer 11

-intrarenal or intrinsic causes
-nephrotic exposure
-Abx, contrast, chemo, myeloma, uric acid, tumor lysis syndrome

Question 12

Acute Glomerulonephritis

Answer 12

-Intrarenal
-inflammation and damage to glomeruli
-autoimmune causes (lupus, IGA, goodpasture, nephropathy)
-vasculitis (polyarteritis, wegners)
-infectious causes (strep, endocarditis, HIV, HEP B/C

Question 13

Initial eval & dx

Answer 13

-Electrolytes-mag, phos, Ca
-ABG
-CXR-Volume overload
-Baseline creatinine level, BUN, bicarbonate
-+/- ultrasound
-Post void residual

Question 14

Creatinine

Answer 14

-Byproduct derived from the metabolism of creatine in skeletal muscle and from dietary meat
-Affected by age, gender, race, muscle mass, protein intake
-12–24-hour lag behind of kidney damage
-Small increase in creatinine level may represent larger decrease in GFR

Question 15

Cystatin C

Answer 15

-Measurement of kidney function
-less influenced by muscle mass or diet
-results affected by inflammation and atherosclerosis
-Expensive
-Estimates still being studied on age, race, and gender

Question 16

Stage 1 of AKI

Answer 16

-Increase in SCr by by ≥0.3 mg/dL
-or ≥1.5 - <2.0 x baseline
-UOP: Less than 0.5 mL/kg per hour for more than 6 hours

Question 17

Stage 2 of AKI

Answer 17

-Increase in SCr by ≥2.0 - <3.0 times baseline
-UOP: Less than 0.5 mL/kg per hour for more than 12 hours

Question 18

Stage 3 AKI

Answer 18

-Increase in SCr by ≥3.0 times baseline
-Less than 0.3 mL/kg per hour for 24 hours or anuria for 12 hours

Question 19

GFR in CKD

Answer 19

-Normal kidney function – GFR above 90mL/min/1.73m2 without proteinuria
1) CKD1 – GFR above 90mL/min/1.73m2 with evidence of kidney damage
2) CKD2 (Mild) – GFR of 60 to 89 mL/min/1.73m2 with evidence of kidney damage
3) CKD3 (Moderate) – GFR of 30 to 59 mL/min/1.73m2
4) CKD4 (Severe) – GFR of 15 to 29 mL/min/1.73m2
5) CKD5 Kidney failure - GFR less than 15 mL/min/1.73m2 or on dialysis, however many patients in CKD5 are not yet on dialysis.

Question 20

Diagnostic testing: UA

Answer 20

appearance, osmolality, specific gravity, eosinophils

Question 21

Dx testing: Urine chemistry

Answer 21

Sodium, creatinine, urea (only if on diuretics)

Question 22

Dx testing: UA with microscopy

Answer 22

Cells, casts, crystals, bacteria, nitrates

Question 23

What do Feurea and Fena tell us?

Answer 23

-Helps to differentiate between prerenal and ATN
-BUN, Cr, Urine Urea, Urine Cr – diuretics
-Na, Cr, Urine Na, Urine Cr – no diuretics
FeUrea + diuretics, FeNa - diuretics
FeX = (urine x/ serum x)/ (urine Cr/serum Cr) x 100

FeNa > 1% in ATN, < 1% in prerenal
FeUrea > 50% in ATN, < 35% in prerenal

Question 24

Dx Testing Prerenal

Answer 24

-Urine specific gravity: >1.018
-Urine sodium: <10mEq/L
-FeNa: <1%, FeUrea: <35%
-Urine Osmo: >500 mOsm/L
-Urine sediment: normal, hyaline casts

Question 25

Dx testing of ATN

Answer 25

-Urine specific gravity: 1.010 -Urine Na: >30-40 mEq/L -FeNa: >1% -FeUrea: >50% -Urine osmo: 280 mOsm/L -Urine Sed: Renal tubular cells, epithelial, granular casts, muddy brown

Question 26

Urine Microscopy Interpretation

Answer 26

-WBC- UTI or asymptomatic -Eosinophils- AIN (acute interstitial nephritis) -Epithelial cells- contaminate -RBC- UTI, Malignancy, Traumatic Cath f/u dipsticks with microscopic exam -Gram Stain- presence of bacteria -Contaminant if polymicrobial growth

Question 27

Urine Microscopy Interpretation: Casts

Answer 27

-RBC—vasculitis, glomerulonephritis -WBC—Interstitial nephritis, pyleonpehritis -Epithelial– ATN, AIN -Waxy—Advanced renal failure -Hylaine—normal in concentrated urine or diuretic use -Fatty—heavy proteinuria (Nephrotic syndrome) -Granular—”muddy brown”, ATN ----High amount of protein in urine may consider a 24 hour urine collection

Question 28

Renal US

Answer 28

-Reserve for ordering when concerned about hydronephrosis or prerenal failure not improving with conservative measures r/o hydronephrosis Swelling of kidney, obstruction of urine due to anatomy, stone, prostate, clots -Kidney size: Normal is 10-13 cm -r/o abscess, cyst -CT stone protocol to r/o stone -Doppler measurement for flow of renal arteries and veins -May not be needed if CT Abdomen/pelvis performed

Question 29

Management of High Risk AKI

Answer 29

-D/c all nephrotoxic agents when possible -ensure volume status and perfusion pressure -consider functional hemodynamic monitoring -monitor serum creatinine and UOP -Avoid hyperglycemia -consider alternatives to radiocontrast procedures

Question 30

Management of AKI: Stage 1

Answer 30

-D/c all nephrotoxic agents when possible -ensure volume status and perfusion pressure -consider functional hemodynamic monitoring -monitor serum creatinine and UOP -Avoid hyperglycemia -consider alternatives to radiocontrast procedures -Non-invasive dx workup -Consider invasive dx workup

Question 31

Management of AKI Stage 2

Answer 31

-D/c all nephrotoxic agents when possible -ensure volume status and perfusion pressure -consider functional hemodynamic monitoring -monitor serum creatinine and UOP -Avoid hyperglycemia -consider alternatives to radiocontrast procedures -Non-invasive dx workup -Consider invasive dx workup -check for changes in drug dosing -consider renal replacement therapy -consider ICU admission

Question 32

Management of AKI Stage 3

Answer 32

-D/c all nephrotoxic agents when possible -ensure volume status and perfusion pressure -consider functional hemodynamic monitoring -monitor serum creatinine and UOP -Avoid hyperglycemia -consider alternatives to radiocontrast procedures -Non-invasive dx workup -Consider invasive dx workup -check for changes in drug dosing -consider renal replacement therapy -consider ICU admission -avoid subclavian catheters if possible

Question 33

Renal Diet

Answer 33

-60 grams of protein (more restricted than CKD) -90 meq low sodium -60 meq potassium -800-1000 mg phosphorus +/- fluid restriction

Question 34

Hyperkalemia Tx

Answer 34

-Ca Gluconate 1.5-3g IV over 2-5 minutes: stabilizes cardiac membrane, prevents arrhythmias: K >6.5 -Insulin 10 u R & D50W 5-10 units IV insulin in 50 mL D50W (25 g) infused over 15-30 min--- K >5.5 -Albuterol 10-20 mg over 10 min vs. 2.5 mg---K >5.5 -Sodium polystyrene sulfonate (Kayex) 15-30 grams PO: K >5.5 -Lasix

Question 35

Hypermagnesia

Answer 35

-Rare problem unless renal failure --Level 4-6 meq/L--nausea, flushing, headache, lethargy, drowsiness, and diminished DTs -Level 6-10-somulence, absent DTs, hypotension, bradycardia -Level >10-muscle and respiratory paralysis, heart block, cardiac arrest

Question 36

Hyperphosphatemia

Answer 36

-Long term effects of CAD, calciphylaxis, secondary hyperparathyrodism and hypocalcemia -Initiation of phosphate binders Calcium-containing phosphate binders. (Calcium Acetate) Non-calcium containing phosphate binders (Sevelamer)

Question 37

Hemodialysis Removes

Answer 37

-Salicylates (ASA) -Theophylline -Lithium -Isopropanol (rubbing alcohol) -Methanol and ethylene glycol **Medications induce metabolic acidosis** Metformin

Question 38

Medications associated with urinary retention

Answer 38

-Antidepressants -Antiarrhythmics -Anticholinergics -Antiparkinson meds -Antipsychotics -Muscle relaxants -Narcotics -Antihistamines

Question 39

Rhabdomyolysis is associated with

Answer 39

-Trauma or crush injuries -Prolonged immobilization -Vigorous exercise -Compartment syndrome -Use of statins -Prolonged seizures

Question 40

Diagnostic Testing of Rhabdomyolysis

Answer 40

-Creatinine Kinase (CK) -AKI w/ CK levels-15,000-20,000 -Urine myoglobin

Question 41

Treatment for Rhabdomyolysis

Answer 41

-Hyperkalemia, hypocalcemia, -hyperphosphatemia, hyperuricemia -Hyperkalemia – tx as previously discussed -Hyperuricemia – Allopurinol -Hydration – 100-200 ml/hr -Lasix if volume overload -Continue until CK level is < 5,000

Question 42

Cardiorenal Syndrome Type 1

Answer 42

-Acute HF leads to worsening kidney function

Question 43

Cardiorenal syndrome type 2

Answer 43

Chronic HF leads to progressive chronic kidney disease

Question 44

Hepatorenal Syndrome

Answer 44

Associated portal hypertension, cirrhosis, ascites, SBP Type 1 – twofold increase in Cr w/ level >2.5 mg/dL in < 2 weeks, UOP < 500 ml/24 hrs Type 2 – less severe Cr reduction w/ ascites that is diuretic resistant

Question 45

Hepatorenal Syndrome: Clinical Features

Answer 45

Diagnosis of exclusion Decompensated liver disease Progressive rise in Cr > 0.3 mg/dl Benign urine sediment No or minimal proteinuria < 500 mg/24 hrs Low Na excretion - < 10meq/L Oliguria

Question 46

Hepatorenal syndrome tx

Answer 46

-Improvement in liver function etiology -Improves with transplantation ICU Norepinephrine to raise MAP Albumin IV x 48 hours 1 g/kg per day -General: Midodrine 7.5 to 15 mg by mouth TID Octreotide-continuous IV 50 mcg/hr) or Subq (100 to 200 mcg TID) Albumin 1g/kg/24 hrs x 48 hrs -Consider TIPS procedure

Question 47

Nephritic & Nephrotic Syndrome

Answer 47

-Collection of symptoms that indicate damage to the glomeruli, not a separate disease

Question 48

Glomerulonephritis PHAROAH Pneumonic

Answer 48

-P: Protein -H: Hematuria -A: Azotemia -R-RBC casts -O-Oliguria -A-Anti-strep titers -H-Hypertension