For Undergraduates

1. Acute Renal Failure
By:
Dr.Leena Hafeez

2. Definition
 Sudden and usually reversible loss of renal function which
develops over days or weeks accompanied by reduction in
urine volume.

3. Etiology

4. The etiology of ARF can be divided into 3 categories.
 PRE-RENAL
 RENAL
 POST RENAL

5. Etiology of Acute
Renal Failure
(Overview)

6. Pre Renal Acute Renal Failure

7. Causes:
Pre-renal causes of ARF include
 Heart Failure.
 Blood/Fluid loss as in major surgery,trauma,dehydration
sec. to severe diarrhea and vomiting.
 Renal artery stenosis/Occlusion.
 Diseases Affecting the arterioles.

8. Pathogenesis:
 In circumstances which dec the perfusion pressure(Heart
failure,Shock,Hypovolemia),Kidneys maintain their perfusion by
constriction of renal vasculature and selective constriction of efferent
arterioles
 Drugs like NASIDs and ACE inhibitors affect these compensatory
mechanisms.
 Prolonged hypo perfusion and drug toxicity halt these compensatory
mechanisms leading to acute decline in GFR

9. History and physical Examination
History:
History of Vomiting,Diarrhea,Surgery or Trauma with blood loss and
history of medications including diuretics,NSAIDs, ACE inhibitors,
and ARBs may be present.
Examination:
Physical signs of poor peripheral perfusion may be present.
Orthostatic hypotension,Tachycardia,Reduced jugular venous
pressure, decreased skin turgor, and dry mucous membranes are
often present in prerenal azotemia

10. Intrinsic Acute Renal Failure

11. Causes
Intrinsic causes of Acute renal failure include
 Acute tubular necrosis:
May occur as a result of Ischemia,sepsis or
Nephrotoxic drugs.
 Glomerular diseases:
Primary or Secondary glomerulonephritis
 Vascular diseases:
E.g. Vasculitis or malignant hypertension

12. Pathogenesis of ATN
 Ischemia,Nephrotoxic agents(drugs and bacteria) or a
combination of these two can cause damage to the
tubular cells leading to their necrosis. Tubular cells shed
and block the tubular lumen along with interstitial edema.
 Tubular cells regenerate from the basement membrane
resulting in recovery of renal function if the patient is
supported in the recovery phase.
 Nephrotoxic drugs leading to ATN include
I. Aminoglycosides
II. Cisplatin
III. Amphotericin B

13. Post renal Acute Renal Failure

14. Causes:
Post renal ARF occurs secondary to any obstruction in the urinary tract
which include:
 Renal stones
 Tumors
 Benign prostatic hyperplasia

15. Fig:
Post Renal
Causes of ARF

16. History and Physical Examination
 Colicky flank pain radiating to the groin suggests acute ureteric
obstruction.
 Nocturia and urinary frequency or hesitancy can be seen in
prostatic disease.
 Abdominal fullness and suprapubic pain can accompany massive
bladder enlargement.
 Definitive diagnosis of obstruction requires radiologic
investigations.

17. Phases of Acute Renal Failure

18. Phases
Acute Renal Failure is divided into 4 phases
 Initiation Phase:
 Oliguric phase:
Lasts 7-14 days. Urine output <400ml/day.
 Diuretic Phase:
Urine output can reach up to 2500ml/day. Adequate fluid replace
required for good recovery
 Recovery Phase:
GFR returns to normal. Renal parameters decline towards the normal
range

19. Investigations

20. Blood Counts
 Full Blood Count:
Anemia may show CKD
Low platelets may indicate DIC and sepsis
 Urea and Creatinine:
Daily raise may exceed up to 5mmole/day
 Serum Electrolytes:
Hyperkalemia
 Albumin:
Low Serum Albumin in nephrotic syndrome and sepsis

21. Urine Analysis
 Proteinuria may indicate glomerular disease
 Hematuria shows obstructive lesions, stone or glomerulonephritis
 Leucocytes may show infection
 Crystals can be specific of drugs or uric acid

22. Radiological Investigations
 Ultrasound:
Small kidneys suggest CKD, Asymmetric kidneys in renal vascular
diseases. Site of obstruction may be seen in post renal causes.
 Doppler Ultrasound:
To rule out renal artery stenosis
 X-ray Chest:
Pulmonary edema in fluid overload
 Nuclear Scans:
I. DMSA Scan
II. DPTA Scan Renal Artery stenosis

23. Specific Investigations:
 Renal Biopsy:
For glomerular diseases, interstitial nephritis
 Serology:
For infections like post streptococcal glomerulonephritis,
Leptospirosis.

24. Management

25. Management
1.Treat the underlying cause:
 Pre renal failure:
Restore the blood volume by transfusing Blood, Plasma or isotonic
saline carefully monitoring CVP and PWP
 Renal Cause of ARF:
I. ATN responds to restoration of renal perfusion
II. Immunosuppressive therapy for glomerulonephritis
 Post renal cause:
Prompt relive of obstruction restores the renal functions.

26. Management
2.Fluid and Electrolyte Balance:
 Strict monitoring of Intake and output
 Daily fluid intake should be equal to output+500ml
 Additional replacement required in case of abnormal losses like
Diarrhea and Vomiting.
3.Hyperkalemia:
Potassium concentration >6mmole/L can cause serious
arrthymias.Immediate intervention required
4.Metabolic Acidosis:
Restoration of blood volume will correct acidosis. Treat with sodium
bicarbonate(50ml of 8.4%) in severe cases.

27. Management
5.Proteins and energy Intake:
 Protein restriction to less than 40g/day.
 Major source of energy should be fats and carbohydrates
 Enteral and parenteral nutrition may be required in patients with
hyper catabolic states(e.g. burns and sepsis)
6.Infection Control:
Prompt diagnosis and treatment with antibiotics required
7.Avoidance of nephrotoxic drugs:
NSAIDS and ACE inhibitors may prolong ARF and should be avoided.
8.Renal replacement therapy:
May be required as supportive management

28. Prognosis
Prognosis of ARF depends upon the severity of Underlying cause
 In Uncomplicated ARF secondary to hemorrhage and Drugs mortality is
low
 ARF associated with Serious Infections and MOF mortality is 50-70%

29. Thank You