Renal

Question 1

What is the main action of renin?

Answer 1

converts angiotensin (from liver) into angiotensin I

Question 2

What is the main action of ACE (angiotensin converting enzyme)?

Answer 2

convert angiotensin I into angiotensin II in lungs

Question 3

What is the main action of angiotensin II?

Answer 3

causes vasoconstriction -> increases BP
stimulates release of aldosterone from adrenal glands
promotes hypertrophy of heart muscle cells

Question 4

What is aldosterone? Where is it released from?

Answer 4

mineralocorticoid, released by adrenal glands

Question 5

What are the main actions of aldosterone?

Answer 5

Increase sodium reabsorption from the distal tubule
Increase potassium secretion from the distal tubule
Increase hydrogen secretion from the collecting ducts

Question 6

What effect does higher sodium reabsorption have on blood pressure?

Answer 6

When sodium is reabsorbed in the kidneys, water follows it by osmosis. This leads to increased intravascular volume and, subsequently, blood pressure.

Question 7

What are the main categories of AKI causes?

Answer 7

prerenal
intrinsic
postrenal

Question 8

What are the prerenal causes of AKI?

Answer 8

ischaemia e.g. in
- renal artery stenosis
- hypovolaemia secondary to vomiting, diarrhoea

Question 9

What are some intrinsic causes of AKI?

Answer 9

intrinsic damage to glomeruli, e.g. due to drugs, toxins, immune-mediated
- glomerulonephritis
- acute tubular necrosis
- acute interstitial nephritis
- rhabdomyolysis
- tumour lysis syndrome

Question 10

What are some postrenal causes of AKI?

Answer 10

obstruction e.g.
- kidney stone in ureter, bladder
- BPH
- external compression of the ureter

Question 11

Who is at an increased risk of AKI?

Answer 11

CKD
organ failure / chronic disease
Hx of AKI
use of nephrotoxic drugs - e.g. NSAIDs, ACEi, ARBs - within the past week
use of iodinated contrast agents in the past week
age 65+

Question 12

What is oliguria?

Answer 12

reduced urine output
less than 0.5 ml/kg/hr

Question 13

How can AKI be detected?

Answer 13

U&Es - rise in electrolytes normally excreted by the kidneys
urinalysis
imaging - renal USD - if no identifiable cause for deterioration or at higher risk of urinary tract obstruction

Question 14

How is AKI managed?

Answer 14

supportive management
- fluid balance
- medication review

Question 15

Which medications are safe to continue in AKI?

Answer 15

paracetamol
warfarin
statins
aspirin
clopidogrel
beta blockers

Question 16

What treatments are available for hyperkalaemia?

Answer 16

1. IV calcium gluconate - to stabilise the cardiac membrane
2. insulin + dextrose infusion
   nebulised salbutamol
   -> to provide short term shift of K from outside into the cells
3. loop diuretics
   dialysis
   -> to remove K from the body

Question 17

What is acute tubular necrosis?

Answer 17

most common intrinsic cause of AKI
necrosis of renal tubular epithelial cells
reversible in early stages if cause is removed

Question 18

What are the main causes of acute tubular necrosis?

Answer 18

1. ischaemia - shock, sepsis
2. nephrotoxins
   - rhabdomyolysis
   - radiocontrast agent
   - lead

Question 19

What are the features of acute tubular necrosis?

Answer 19

raised urea, creatinine, potassium
muddy brown casts in urine

Question 20

What are the phases of acute tubular necrosis?

Answer 20

oliguric
polyuric
recovery

Question 21

Why do patients with CKD have anaemia?

Answer 21

reduced erythropoietin production
reduced Fe absorption

Question 22

What are the most common causes of polyuria?

Answer 22

diuretics, caffeine, alcohol
DM
lithium
HF