1. Acute Renal Failure Ebadur Rahman
FRCP (Edin),FASN, Specialty Certificate in Nephrology (UK)
MRCP (UK), DIM (UK), DNeph (UK), MmedSciNephrology (UK).
Consultant & clinical tutor
Department of Nephrology PSMMC

2. Acute Renal Failure 30 different definition
Rapid decline in the GFR over days to weeks.
Cr increases by >0.5 mg/dL
GFR <10mL/min, or <25% of normal

3. KDIGO AKI Definition
Acute kidney injury/impairment (AKI) is defined as any of the following:
Increase in SCr by >0.3 mg/dl (>26.4 µmol/L) within 48 hours, or
Increase in SCr by >1.5-fold above baseline which is known or presumed to have occurred within 7 days, or
Urine volume <0.5 ml/kg/h for 6 hours.
KDIGO AKI GL. Kidney inter., Suppl. 2012; 2: 1–138

4. Definitions
Anuria: No UOP Oliguria: UOP< mL/d Azotemia: Incr Cr, BUN Uremia : symptomatic azotemia

5. KDIGO AKI Staging
Stage
Serum creatinine
Urine output 1
≥ times baseline (7 days) OR
26.5 µmol/L increase (48 hrs)
< 0.5 ml/kg/hr for hrs 2
≥ times baseline
< 0.5 ml/kg/hr for ≥12hrs 3
≥ 3.0 times baseline
increase in creatinine to ≥ 354 µmol/L
Renal replacement therapy
< 0.3 ml/kg/hr for ≥24hrs
Anuria for ≥ 12hrs
KDIGO AKI Guideline. Kidney inter., Suppl. 2012; 2: 1–138

8. ATN
Prerenal Cr
increases at /day
increases slower than 0.3 /day
U Na, FeNa
UNa>40
FeNa >2%
UNa<20
FeNa<1% UA
epi cells, granular casts
Normal
Response to volume
Cr won’t improve much
Cr improves with IVF
BUN/Cr
10-15:1
>20:1

9. FeNa = (urine Na x plasma Cr) (plasma Na x urine Cr)

10. More FeNa FeNa 1%-2% 1. Prerenal-sometimes 2. ATN-sometimes
3. AIN-higher FeNa due to tubular damage
FeNa >2%
ATN
Damaged tubules can't reabsorb Na

11. Calculating FeNa after pt has gotten Lasix...
1. Fractional Excretion of Lithium (endogenous)
2. Fractional Excretion of Uric Acid
3. Fractional Excretion of Urea

12. Causes of ARF in hospitalized pts
45% ATN
Ischemia, Nephrotoxins
21% Prerenal
CHF, volume depletion, sepsis
10% Urinary obstruction
4% Glomerulonephritis or vasculitis
2% AIN
1% Atheroemboli

13. Presentation of Kidney Disease
Normal Renal Function
(hematuria/Proteinurea)
Asymptomatic,
only incidental finding on routine checkup
AKI
Abnormal radiological imaging of kidney
Various stages of impairment of CKD (1-5)

15. Acute Kidney Injury and Sepsis
AKI occurs in
19% culture positive in moderate sepsis
23% culture positive in severe sepsis
51% culture positive in septic shock
70% mortality in sepsis
and AKI combined
Rangel-Frausto et al. JAMA 1995;273:
Schrier & Wang NEJM 2004;351:159-69

16. ARF: Signs Hyperkalemia HTN Pulmonary edema Ascites Asterixis
Encephalopathy

17. Diagnostic approach History Physical examination
Assessment of renal function by eGFR
Careful examination of urine
Radiological imaging of Kidney
Serological Testing
Tissue Diagnosis by Renal Biopsy

18. ARF: Focused History Vomiting? Diarrhea?
Hx of heart disease, liver disease, previous renal disease, kidney stones, BPH?
Any edema, change in
urination?
Any new medications?
Any recent radiology studies?
Rashes?

20. Physical Exam Volume Status Mucus membranes, orthostatics
Cardiovascular
JVD, rubs
Pulmonary
Decreased breath sounds
Rales
Rash (Allergic interstitial nephritis)
Large prostate
Extremities (Skin turgor, Edema)

21. W/U for ARF Chem Urine Kidney U/S - r/o hydronephrosis
Urine electrolytes and Urine Cr to calculate FeNa
Urine eosinophils
Urine sediment: casts, cells, protein
Uosm
Kidney U/S - r/o hydronephrosis

29. Immediate therapy
 — The management of life-threatening Common complications of AKI include the following:
●Fluid overload
●Hyperkalemia (serum potassium >5.5 mEq/L) or a rapidly increasing serum potassium
●Signs of uremia, such as pericarditis, or an otherwise unexplained decline in mental status
●Severe metabolic acidosis (pH <7.1)

30. Indications for dialysis therapy —IN AKI include:
Fluid overload that is refractory to diuretics.
Hyperkalemia (serum potassium concentration >6.5 mEq/L) or rapidly rising potassium levels, refractory to medical therapy.
Metabolic acidosis (pH <7.1) in patients in whom the administration of bicarbonate is not indicated, such as those with volume overload (who would not tolerate the obligate sodium load), or those with lactic acidosis or ketoacidosis, in whom bicarbonate administration has not been shown to be effective.
Signs of uremia such as pericarditis, neuropathy, or an otherwise unexplained decline in mental status.

33. A. ATN B. Glomerulo-nephritis C. Dehydration D. AIN from NSAIDs
A 22yo male with sickle cell anemia and abdominal pain who has been vomiting nonstop for 2 days. BUN=45, Cr=2.2. previous u& e normal.
A. ATN B. Glomerulo-nephritis C. Dehydration D. AIN from NSAIDs
hyaline cast, normal finding, Prerenal.

34. Prerenal ARF Hyaline casts can be seen in normal pts
NOT an abnormal finding
UA in prerenal ARF is normal
Prerenal: causes 21% of ARF in hosp. pts
Reversible
Prevent ATN with volume replacement
Fluid boluses or continuous IVF
Monitor Uop

35. Prerenal causes Intravascular volume depletion Hemorrhage
Vomiting, diarrhea
“Third spacing”
Diuretics
Reduced Cardiac output
Cardiogenic shock, CHF, tamponade, huge PE....
Systemic vasodilation
Sepsis
Anaphylaxis, Antihypertensive drugs
Renal vasoconstriction
Hepatorenal syndrome

36. Intrinsic ARF Tubular (ATN) Interstitial (AIN)
Glomerular (Glomerulonephritis)
Vascular

37. You evaluate a 57yo man w/ oliguria and rapidly increasing BUN, Cr.
ATN
Acute glomerulonephritis
Acute interstitial nephritis
Nephrotic Syndrome
muddy brown granular casts

38. Muddy brown granular casts

39. ATN Renal tubular epithelial cell casts (below)
epithelial cell cast (cells are larger than WBCs; have nuclei)

40. ATN
Broad casts (form in dilated, damaged tubules)

41. ATN Causes 1. Hypotension Relative low BP
May occur immediately after low BP episode or up to 7 days later!
2. Post-op Ischemia
Post-aortic clamping, post-CABG
3. Crystal precipitation
4. Myoglobinuria (Rhabdo)
5. Contrast Dye
ARF usually 1-2 days after test
6. Aminoglycosides (10-26%)

42. ATN—What to do Remove any offending agent
IVF
Try Lasix if euvolemic pt is anuric
Dialysis
Most pts return to baseline Cr in 7-21 days

43. 56yo woman with previously normal renal function now has BUN=24, Cr 1
56yo woman with previously normal renal function now has BUN=24, Cr Which drug is responsible?
Ibuprofen
Paracetamol
Prednisolone
WBC cast
which drug? gentamicin for SBE, motrin for RA, ASA for CAD,

44. WBC Casts
Cells in the cast have nuclei (unlike RBC casts) Acute Interstitial Nephritis

45. Acute Interstitial Nephritis
70% Drug hypersensitivity
30% Antibiotics: PCNs (Methicillin), Cephalosporins, Cipro
Sulfa drugs
NSAIDs
Allopurinol...
15% Infection
Strep, Legionella, CMV, other bact/viruses
8% Idiopathic
6% Autoimmune Dz (Sarcoid, Tubulointerstitial nephritis/Uveitis)

46. AIN from Drugs Renal damage is NOT dose-dependent
May take wks after initial exposure to drug
Up to 18 mos to get AIN from NSAIDS!
But only 3-5 d to develop AIN after second exposure to drug
Fever (27%)
Serum Eosinophilia (23%)
Maculopapular rash (15%)
Bland sediment or WBCs, RBCs, non-nephrotic proteinuria
WBC Casts are pathognomonic!
Urine eosinophils on Wright’s or Hansel’s Stain
Also see urine eos in RPGN, renal atheroemboli...

47. AIN Management Remove offending agent
Most patients recover full kidney function in 1 year

48. You evaluate a 32yo woman with HTN, oliguria, and rapidly increasing Cr, BUN.
ATN
Acute glomerulonephritis
Acute interstitial nephritis
Nephrotic Syndrome
RBC casts

49. Acute Glomerulonephritis
RBC casts: cells have no nuclei
Casts in urine: think INTRINSIC renal dz
If she had a sore throat 10 days ago, think Postinfectious Proliferative Glomerulonephritis

50. What are these?
Another pic of RBC casts; just look different

51. Glomerular Hematuria (dysmorphic RBCs) RBC casts
Lipiduria (increased glomerular permeability)
Proteinuria (may be in nephrotic range)
Fever, rash, arthralgias, pulmonary sx
Elevated ESR, low complement levels

52. Acute Glomerulonephritis Hemolytic-Uremic Syn Rhabdomyolysis
A 21y woman with Breast Cancer s/p chemo in the ER has weakness, fever, rash. WBC=15.4, Hct 24, Cr 2.9, LDH 600, CK=600. UA=3+ prot, 3+blood, 20 RBC.blood film schistocytes+++
Nephrotic Syn
Systemic Vasculitis
Acute Glomerulonephritis
Hemolytic-Uremic Syn
Rhabdomyolysis

53. TTP Order blood smear to r/o TTP TTP associated with malignancy, chemo
TTP may mimic Glomerulonephritis on UA (RBCs, WBCs)
Thrombocytopenia, anemia not consistent with nephrotic or nephritic syndrome
Need CK in the thousands to cause ARF

54. Microvascular ARF
TTP/HUS
HELLP syndrome
Plasma exchange

55. Macrovascular ARF Aortic Aneurysm
Renal artery dissection or thrombosis
Renal vein thrombus
Atheroembolic disease
New onset or accelerated HTN?
Abdominal bruits, reduced femoral pulses?
Vascular disease?
Embolic source?

56. Your 70 yo male inpatient with baseline Cr=1
Your 70 yo male inpatient with baseline Cr=1.1 had negative cardiac cath 4 days ago, now Cr=2.2 and
Renal Artery Stenosis
Contrast-Induced Nephropathy
C. Abdominal Aortic Aneurysm
D. Cholesterol Atheroemboli

58. Renal Atheroembolic disaese
1% of Cardiac caths: atheromatous debris scraped from the aortic wall will embolize
Retinal
Cerebral
Skin (Livedo Reticularis, Purple toes)
Renal (ARF)
Gut (Mesenteric ischemia)
Unlike in Contrast-Induced Nephropathy, Cr will NOT improve with IVF
Diagnosis of exclusion: will NOT show up on MRI or Renal U/S; WILL show up on renal bx
Tx: supportive

60. You’re called to the ER to see...
A 35yo woman with previously normal renal function now with BUN=60, Cr=3.5.
her K=7.8 Cxray –puledema
What do you do next

61. Send her for Stat CT with IV contrast
A pt with chronic lung disease has acute pleuritic pain and desats to 92%RA. You want to r/o PE but her Cr=1.4. Can you get a CT with IV contrast?
Send her for Stat CT with IV contrast
Send her for Stat CT without IV contrast
C. Just give her heparin
Begin IV hydration
Begin pre-procedure Mannitol
Get a VQ scan instead

62. Contrast-Induced Nephrotoxicity
Cr increases by 25% post-procedure
Contrast causes renal vasoconstriction renal hypoxia
Iodine itself may be renally toxic
If Cr>1.4, use pre-procedure prophylaxis

63. Pre-Procedure Prophylaxis
1. IVF ( 0.9NS)
1-1.5 mg/kg/hour x12 hours prior to procedure and 6-12 hours after
(N-acetylcysteine)