6. Renal system

Question 1

What is the renal system?

Answer 1

= responsible for the removal of wastes, as well as fluid and electrolyte balance

Question 2

Two main causes of kidney disease

Answer 2

• diabetes and hypertension are the two main causes of chronic kidney disease

Question 3

Function of the kidney

Answer 3

• filters blood (1.2L min)
• excretes unwanted waste products  toxins and metabolic wastes)
• Regulates fluid and electrolyte balance

Question 4

Biochemical changes (changes in electrolytes) that you would see with someone with acute renal failure and chronic renal failure

Answer 4

• Hyperkalaemia (kidney cannot excrete potassium)  leads to abdominal cramping, muscle weakness, paralysis and cardiac arrest
  o Caused by  Excessive oral intake, renal failure, deficit of aldosterone, use of potassium sparing diuretic drugs, crush injuries or burns (K+ leaks out), prolonged or severe acidosis may displace potassium from cells
• Hypernatremia (kidney cannot excrete excessive sodium)  leads to high blood pressure, muscle twitching, weakness and disorientation
• Hypermagnesemia  leads to a decrease in blood pressure, decreased heart rate, coma and cardiac arrest
• Hypercalcemia  leads to muscle spasms, abnormal heart rhythm

Question 5

What is chronic kidney disease (CKD)

Answer 5

= progressive loss of kidney function

• The destruction of renal mass with irreversible sclerosis and loss of nephrons leads to progressive decline in GFR
• GFR is clinically indicated by kidney damage or a decreased kidney glomerular

Question 6

Progression of chronic kidney disease

5 stages

Answer 6

1. Normal Kidney function (high GFR > 90ml)
2. Mild kidney damage –> Kidney attempts to compensate for renal damage by hyperfiltration
3. Moderate kidney damage Hyperfiltration through the nephrons, causes further loss of function
4. Severe kidney damage - severe reduction of GFR (15-29 ml/min)
5. End stage kidney disease - established kidney failure (<15ml/min)

Question 7

What are the factors contributing to chronic kidney disease

Answer 7

= Long term hypertension and diabetes

• congestive heart failure
• lupus
• sickle cell anemia
• polycystic kidney disease
• analgesic neuropathy

Question 8

What is anemia?

Answer 8

= A condition in which the blood doesn’t have enough healthy red blood cells. (deficiency of RBC)

Question 9

Why might anemia occur as a result of chronic kidney disease?

Answer 9

• Iron deficiency Occurs as a result of CKD = body uses iron to make RBC – therefore the iron deficiency leads to anaemia
• When kidneys are diseased or damaged, they do not make enough EPO. As a result, the bone marrow makes fewer red blood cells, causing anaemia

Question 10

What is Acute kidney injury?

Answer 10

• AKI is a sudden decline in kidney function and leads to disorders of acid/base, electrolyte and fluid balance.
• RIFLE staging system was required

R- risk  I – injury  F - failure  L – loss  E - end stage renal failure

Question 11

What does pre-renal, intrarenal (intrinsic) and post renal mean?

Answer 11

Pre renal = problems with blood supply

intrarenal (intrinsic) = damage to kidney

Post renal = obstruction of urinary tract

Question 12

Discuss the

pre-renal (problems with blood supply)

of Acute kidney injury

Answer 12

1. Hypovolaemia (volume depletion) – haemorrhage, vomiting, renal fluid loss
2. Low cardiac output – disease of myocardium, pulmonary
3. Alterations in renal system vascular resistance ratio
4. Renal hypoperfusion
5. Hyper viscosity syndrome e.g. polycythaemia

Clinical signs  thirst, tachycardia, orthostatic dizziness, reduced JVP, reduced axillary sweating, dry mucous membranes

Question 13

discuss the

intrarenal (intrinsic)

of acute kidney injruy

Answer 13

1. Diseases of the glomeruli or renal microvasculature e.g. SLE, glomerulonephritis
2. Acute tubular necrosis e.g. ischaemia, toxins
3. Intestinal nephritis e.g. NSAIDs, Lymphoma

Clinical signs  fever, joint pain, flank pain, headache, dizziness, confusion, seizure, oliguria, oedema, hypertension, heart failure

Question 14

discuss the

post renal

of acute kidney injury

Answer 14

Obstruction

• Calculi
• Cancer causing obstruction
• Prostatic hypertrophy
• Stricture of the urethra

Clinical signs  suprapubic and flank pain, Colicky pain

Question 15

What is chronic renal failure?

Answer 15

= progressive loss of kidney function

Question 16

Pre renal of chronic renal failure?

Answer 16

sudden reduction in blood flow in kidney

• poor cardiac function
• chronic liver failure
• atherosclerosis of the renal arteries

Question 17

Intrarenal of chronic renal failure?

Answer 17

changes within the kidneys

• diabetic nephropathy - most common cause of CFT, chronic glomerular, nepritis, vasculitis, polycystic kidney disease

Question 18

Post-renal of chronic renal failure?

Answer 18

Obstructions can cause urinary backflow and put pressure on the kidneys.

• Examples include: kidney stones, bladder outlet obstruction, retroperitoneal fibrosis

Question 19

what is an upper urinary obstruction?

Answer 19

= a blockage of the passage of urine (can occur at any site along the tract)

Question 20

causes of an upper urinary obstruction?

Answer 20

• Narrowing of the ureter or urethra
• Compression due to either a congenital defect or physical compression from a blood vessel, scaring, tumour or abdominal inflammation
• Renal calculi (kidney stones)
• Malignancy in either the renal pelvis, ureter, prostate or bladder

Question 21

Effect on the kidney function of urinary obstruction:

Answer 21

effect depends on size of obstruction

• Initially the urine backs up which leads to the dilation of the ureter, renal pelvis and calyces
• Within 14 days it will affect both the proximal and distal part of nephron
• Within 28 days the backflow of urine will lead to the glomeruli becoming damaged and consequently the renal cortex and medulla will decrease in size
• total obstruction = leads to damage of renal tubule in 4 hours and is irreversible if not corrected within 4 weeks