Renal Failure

Question 1

Describe the normal function of the kidneys (all functions), ureters and bladder?

Answer 1

It filters waste from the blood and reabsorbs important products, and is therefore vital in fluid homeostasis.

The filtered waste aka urine feeds into the collecting ducts of the kidneys and into the ureters (peristaltic) were it is transported to the bladders.

The bladder is filled and once it stretches to a certain amount it voids however this is also under conscious control and therefore we can learn to suppress this reflex aka continence.

Other functions of the kidney include:
Acid/Base balance
Electrolyte balance
BP control
Vit D and EPO production

Question 2

Describe the anatomical location of the kidneys ureters and bladder.

Answer 2

Kidneys are retroperitoneal organs located between T12 and L3 with the left kidney usually slightly higher than the right.

Ureters leave the pelvis of the kidneys and travel obliquely towards the bladder.

Bladder is a extrapertioneal muscular urine reservoir which lies just deep to the pubic symphysis.

Question 3

What are the pre-renal causes of renal failure?

Answer 3

Pre-renal: (40-70%)

• Volume depletion (haemorrhage, severe vomiting or diarrhoea, burns, inappropriate diuresis)
• Oedematous states: cardiac failure, cirrhosis, nephrotic syndrome.
• Hypotension (cariogenic shock, sepsis, anaphylaxis)

Renal hypo-perfusion:

• Renal aa stenosis or blockage (surgical, thromboembolic)
• Drugs: NSAIDs and ACEI due to reduction in BP maintenance systems (prostoglandins and angiotensin)

-Reduced CO: MI/arrhythmias

Question 4

What are the renal causes of renal failure?

Answer 4

Renal: (20-50%)
-Diabetic Nephropathy

• Glomerulonephritis
• Acute Tubular Necrosis (due to prolonged hypo perfusion) or tubular disease due to nephrotoxins
• Acute interstitial nephritis due to drugs (eg, NSAIDs), infection or autoimmune diseases.
• Infiltrative disease

Question 5

What are the post renal causes of renal failure?

Answer 5

Post Renal: (10%)
Ureteric obstruction———> hydronephrosis*
Bladder obstruction predisposes to UTI’s and could also cause hydronephrosis

*increased pressure causes distension and dilatation of the renal pelvis and calyces causing damage

Question 6

What can cause ureteric/bladder obstruction?

Answer 6

Extra-luminal:

• Tumour
• Prostatic hypertrophy/Ca

Mural:

• Ureteric stricture
• Pelvic mass

Luminal:
-Renal caliculi

Question 7

What are the life threatening complications of acute renal failure?

Answer 7

• Severe fluid overload causing severe pulmonary oedema. (caused by hypoproteinuria)
• Metabolic Acidosis (acid bace balance impaired)
• Hyperkalaemia

Uraemic complications:
Pericarditis
Encepalopathy

Question 8

What is the general management of a patient with a acute renal failure?

Answer 8

1. Check K+ level if raised protect heart from arrhythmias and correct K+ level
2. Monitor and correct fluid balance. (Input/output charts, clinical assessment, body weight, UO monitoring)
3. Treat underlying cause if this has not been done already

Question 9

Define dehydration and what signs/symptoms may be seen?

Answer 9

Greater than 1% of body weight loss through fluid loss.

Dry mucosal surfaces.
Fatigue.
Headache.
Impaired cognitive function.

Question 10

What are the indications for renal dialysis?

Answer 10

Uraemia:
Pericarditis
Encephalopathy

Pulmonoary oedema

Refractive hyperkalaemia (greater than 6.5mmol)

Overdose of salicyalates or ethylene glycol