Kidney Failure

Question 1

Types of renal failure :

Answer 1

1. Acute renal failure - A sudden loss of kidney function caused by an illness, an injury or toxin that stresses the kidney

Caused :
- traumatic, acute intoxication, part of multiorgan failure, infection

2. Chronic renal failure - A long n slow process where kidneys lose their ability to function (irreversible)

Caused :
- secondary to high BP, diabetes, chronic bacterial inflammation, cystic kidney, autoimmune disease

Question 2

Acute renal failure

Answer 2

• Sudden reduction in renal function, filtration (within hours) –low
  GFR
• Acute renal failure (ARF) or acute kidney injury (AKI)
• Elevated BUN and creatinine
  oliguria, water and fluids disturbances; and electrolyte
  derangement
• Normally associated with oliguria (< 30ml/hr or < 400ml/24 hours)
• Reversible if diagnosed and treated early
• Azotemia (high nitrogenous waste products)
• Anuria (<100ml/24 hours)

Question 3

Types of acute renal failure :

Answer 3

1. Pre renal
2. Post renal
3. Intrictic

Question 4

Pre renal

Answer 4

A. Causes :
• Renal
vasoconstriction
• Hypotension
• Hypovolemia
• Hemorrhage
• Renal artery
obstruction
• Shock
• Dehydration
• Heart failure

B. Impaired renal
blood flow

C. Reduced GFR
Hypoxemia,
ischemia (when
BF less 25%)
Necrosis
D. Electrolyte
imbalance,
metabolic
acidosis,
azotemia
• Oliguria
• Low GFR
• High BUN

Question 5

Pre renal azotemia

Answer 5

▪ Slow blood flow increase reabsorption of UREA
while amount of creatinine being secreted is not
significantly affected.
▪ Thus, increased BUN: Cr ratio occur in pre-renal
causes
▪ Renal hypoperfusion 🡪 GFR
▪ (without damage to the renal parenchyma)
▪ Adaptive response
▪ Maintaining a normal GFR is dependent on
adequate renal perfusion.
▪ Functional renal failure - decreased volume receptor
stimulation
▪ The primary defense against effective volume
depletion
▪ Initial compensatory defenses involve increased
adrenergic and angiotensin II activity as well as
increased aldosterone influence on the tubule; the
net effect is increased proximal and distal tubular
reabsorption.

Question 6

Intrinsic renal

Answer 6

▪ four structures of kidney 🡪 tubules, glomeruli, the
interstitium, and intra-renal blood vessels
▪ Acute tubular necrosis (ATN) - AKI from damage to
the tubules 🡪 most common type of intrinsic (75%)
▪ glomerular damage occurs in severe cases of acute
glomerulonephritis (GN).
▪ vascular damage occurs because injury to intra-renal
vessels decreases renal perfusion and diminishes GFR
▪ interstitial nephritis occurs due to an allergic reaction
to a variety medications or an infection

• Dysfunction of nephron
• impaired renal blood flow
• surgery
• Sepsis
• severe burns
• nephrotoxic (eg: antibiotics)
• diabetes mellitus
• acute glomerulonephritis
• Pyelonephritis
• Ischemia
• *Acute tubular necrosis
Causes:
Oliguria, azotemia, uremia

Question 7

Post renal arf

Answer 7

▪ Causes: Obstruction or infection from the renal
tubule to urethra:
▪ Bladder (tumour, neurogenic bladder)
▪ Ureter (calculi)
▪ Urethra (*prostatic hyperplasia)
▪ Block urine outflow
▪ ↑ pressure in Bowman’s capsule causes ↓
glomerular filtration 🡪 diminish GFR
▪ May present as anuria or intermittent urine flow
▪ Timely reversion of pre-renal or post-renal causes
usually results in prompt recovery of function, but
late correction can lead to kidney damage.