CAUSES :
A. PRERENAL
1. HYPOVOLEMIA
- HAERMORRHAGE, BURNS, DEHYDRATION
- GASTROINTESTINAL FLUID LOSS : VOMITING, SURGICAL DRAINAGE, DIARRHOEA
- RENAL FLUID LOSS - DIURETICS, OSMOTIC DIURESIS9 EG. DIABETES MELLITUS ), HYPOADRENALISM
- SEQUESTRATION IN EXTRAVASCULAR SPACE - PACREATITIS, PERITONITIS, TRAUMA, BURNS, SEVERE HYPOALBUMINEMIA
2. LOW CARDIAC OUTPUT
- DISEASES OF MYOCARDIUM, VALVES, PERICARDIUM; ARRYTHMIAS; TEMPONADE
- OTHERS - PULMONARY HYPERTENSION, MASSIVE PULMONARY EMBOLISM, POSITIVE PRESSURE MECHANICAL VENTILATION
3. ALTERED RENAL SYSTEMIC VASCULAR RESISTANCE RATIO
- SYSTEMIC VASODILATATION: SEPSIS, ANTIHYPERTENSIVES, AFTERLOAD REDUCERS, ANAESTHESIA, ANAPHYLAXIS
- RENAL VASOCONSTRICTION: HYPERCALCEMIA, NOREPINEPHRINE, EPINEPHRINE, CYCLOSPORINE, AMPHOTERICIN B
- CIRRHOSIS WITH ASCITES ( HEPATORENAL SYNDROME)
4. RENAL HYPOPERFUSION WITH IMPAIRMENT OF RENAL AUTOREGULATORY RESPONSES :
CYCLOOXYGENASE INHIBITORS, ANGIOTENSIN-CONVERTING ENZYME INHBITORS
5. HYPERVISCOCITY SYNDROME ( RARE )
- MULTIPLE MYELOMA, MACROGLOBULINEMIA, POLYCYTHEMIA
B. INTRINSIC RENAL CAUSES
1. RENOVASCULAR OBSTRUCTION ( BILATERAL OR UNILATERAL IN THE SETTING OF ONE FUNCTIONING KIDNEY )
- RENAL ARTRY OBSTRUCTION : ATHEROSCLEROTIC PLAQUE, THROMBOSIS, EMBOLISM, DISSECTING ANEURYSM, VASCULITIS
- RENAL VEIN OBSTRUCTION : THROMBOSIS, COMPRESSION
2. DISEASE OF GLOMERULI OR RENAL MICROVASCULATURE
- GLOMERULONEPHRITIS & VASCULITIS
- HEMOLYTIC UREMIC SYNDROME, THROMBOTIC THROMBOCYTOPENIC PURPURA, DISSEMINATED INTRAVASCULAR COAGULATION, TOXEMIA OF PREGNANCY, ACCELERATED HYPERTENSION, RADIATION NEPHRITIS, SLE, SCLERODERMA
3. ACUTE TUBULAR NECROSIS
- ISCHEMIA : AS FOR PRERENAL ARF ( HYPOVOLEMIA, LOW CARDIAC OUTPUT, RENAL VASOCONSTRICTION, SYSTEMIC VASODILATATION), OBSTETRIC COMPLICATIONS ( ABRUPTIO PLACENTA, PPH )
- TOXINS :
* EXOGENOUS - RADIOCONTRAST, CYCLOSPORIN, ANTIBIOTICS, CHEMOTHERAPY, ORGANIC SOLVENTS, ACETAMINOPHEN, ILLEGAL ABORTIFACIENTS
* ENDOGENOUS - RHABDOMYOLYSIS, HEMOLYSIS, URIC ACID, OXALATE, PLASMA CELL DYSCRASIA( EG. MYELOMA)
4. INTERSTITIAL NEPHRITIS
- ALLERGIC : BETA-LACTAMS, SULPHONAMIDES, RIFAMPICIN, NSAIDS, DIURETICS, CAPTOPRIL
- INFECTIONS : BACTERIAL ( AC PYELONEPHRITIS, LEPTOSPIROSIS), VIRAL ( CYTOMEGALOVIRUS), FUNGAL ( CANDIDIASIS )
- INFILTRATION : LYMPHOMA, LEUKEMIA, SARCOIDOSIS
- IDIOPATHIC
5. INTRATUBULAR DEPOSITION & OBSTRUCTION
- MYELOMA PROTEINS, URIC ACID, OXALATE, ACYCLOVIR, METHOTREXATE, SULPHONAMIDES
6. RENAL ALLOGRAFT REJECTION
C. POSTRENAL ARF
1. URETERIC : CALCULI, BLOOD CLOT, SLOUGHED PAPILLAE, CANCER, EXTERNAL COMPRESSION( RETROPERITONEAL FIBROSIS)
2. BLADDER NECK : NEUROGENIC BLADDER, PROSTATIC HYPERTROPHY, CALCULI, CANCER, BLOOD CLOT
3. URETHRA : STRICTURE, CONGENITAL VALVE, PHIMOSIS
OTHER TESTS -
* SERUM SODIUM - MAY BE HIGH OR LOW
* SERUM POTASSIUM - HIGH OR NORMAL
* PARATHYROID HORMONE LEVELS - HIGH IN CHR RENAL FAILURE
* SERUM CREATININE - HIGH
* BLOOD UREA & BUN - HIGH
* SERUM URIC ACID - HIGH
* CREATINE KINASE( CPK ) LEVELS - HIGH
* SERUM PHOSPHATES - HIGH
* SERUM CALCIUM - LOW
* CREATININE CLEARANCE ( ML/MIN ) = (140 - AGE) X LEAN BODY WT(KG) / ( DEVIDED BY ) PLASMA CREATININE ( MG / ML ) X 72
* FRACTIONAL EXCRETION OF SODIUM(FENA) = URINE SOD X PLASMA CREATININE X 100 / ( MULTIPLIED BY ) PLASMA CREATININE X URINE CREATININE
* BUN/PLASMA CR. RATIO - IF > 20:1( PRERENAL AZOTEMIA) & 10-15:1 THEN OLGURIC AC RENAL FAILURE
* URINE SODIUM - < 20 ( PRERENAL AZOTEMIA ) & > 40 ( OLIGURIC AC RENAL FAILURE )
* URINE OSMOLALITY - >500 ( PRERENAL AZOTEMIA & < 350 ( OLIGURIC AC RENAL FAILURE )
* FRACTIONAL EXCRETION OF SOD - < 1% ( PRERENAL AZOTEMIA) & >2% ( OLIGURIC AC RENAL FAILURE )
* URINE / PLASMA CREATININE - >40 ( PRERENAL AZOTEMIA & <20 ( OLIGURIC AC RENAL FAILURE )
* RENAL BIOPSY