Acute kidney injury and nephritic/nephrotic syndrome

Question 1

Functions of kidney

Answer 1

• Excretion of toxins
• Control of sodium and electrolytes potassium
• Acid base balance
• Fluid balance
• Blood pressure
• Activation vitamin D, phosphate excretion
• Anaemia, Production of erythropoeitin

Question 2

Nephron filtration

Answer 2

Bowman’s capsule - 100% filtrate produced
Proximal tubule - 80% filtrate reabsorbed - Active and passive absorption
Loop of henle - 6% filtrate reabsorbed - H2O and salt conservation
Distal tubule - 9% filtrate reabsorbed - variable reabsorption, active secretion
Collecting tubule - 4% filtrate reabsorbed - variable salt and H2O reabsorption

Urine vol = 1% total filtrate volume

Question 3

AKI stage 1 - serum creatinine and urine output criteria

Answer 3

Increase in serum creatinine of 26 micromol/litre or more within 48 hrs or 1.5 to 2-fold increase from baseline

Less than 0.5ml/kg/hr for more than 6 hrs

Question 4

AKI stage 2 - serum creatinine criteria and urine output criteria

Answer 4

Increase in serum creatinine to more than 2 to 3-fold from baseline

Less than 0.5 ml/kg/hr for more than 12 hrs

Question 5

AKI stage 3 - serum creatinine criteria and urine output criteria

Answer 5

Increase in serum creatinine to more than 3-fold from baseline or serum creatinine more than 354 micromol/litre with an acute increase of at least 44 micromol/litre

Less than 0.3mol/kg/hr for 24 hrs or anuria for 12 hrs

Question 6

Rise in serum creatinine > 50% baseline

Answer 6

Baseline creatinine of 80 mmol/L

Rises to 120 mmol/L

Significant kidney injury

This is the moment to act – it is too late when the creatinine reaches 400

Remember what the normal creatinine for the patient is , slight femal normal may be 60 so 50% change is serum creatinine will be 90
Large muscular man normal may be 110 mmol/l

Question 7

Causes of AKI - pre-renal

Answer 7

Decrease in perfusion pressure resulting in ischaemia or infarction

Low BP, low circulating volume
MI, GI Bleed, septic shock,dehydration

Renal artery stenosis

VERY LIKELY

Question 8

Causes of AKI - renal

Answer 8

Direct toxic effects
Drugs,

Overproduction leading to blockage of the tubules
Rhabdomyolysis, myeloma,

Inflammation in the kidney
GN, interstitial nephrits, ATN(acute tubular necrosis)

UNLIKELY

Question 9

Causes of AKI - post-renal

Answer 9

Outflow obstruction

Which level

Stones, ureteric strictures, BPH, retention, urethral strictures

UN-LIKELY

Question 10

Symptoms and signs of renal disease

Answer 10

• Fluid overload
• Abnormalities of K/Na/HCO3
• Abnormalities urea/creatinine
• Abnormalities blood pressure
• Symptoms and signs of other organ disease (can present acutely or chronically)

Question 11

Causes of polyuria

Answer 11

Post relief of obstruction
Drinking large volumes (?diabetes)
Some forms of AKI
Rare endocrine causes

Question 12

Management of polyuria

Answer 12

Encourage the patient to drink
Depending on your assessment of fluid balance
Provide iv fluids to match the output+/- additional input if dry
Once renal function is beginning to improve reduce to 75% of urine output

Question 13

Management of oliguria

Answer 13

Depending on your assessment of fluid balance

If you have given 2-3 litres and cant see blood on the floor ask for help…..