Renal

Question 1

What are some causes of AKI? Categorise them

Answer 1

Prerenal:
- volume depletion
- reduced cardiac output
- systemic vasodilation => renal hypoperfusion
- drugs e.g. NSAIDs, ACE-i

Renal:
- acute tubular necrosis
- acute interstitial nephritis
- vascular
- glomerular

Postrenal:
- obstruction - stones, tumours, strictures, prostatic hypertrophy

Question 2

What urine analysis findings can help investigate AKI?

Answer 2

🔹urine dipstick
- urinary tract infection: leucocytes +/- nitrites
- glomerulonephritis: haematuria + leucocytes
- acute interstitial nephritis: leucocytes by themselves

🔹microscopy, culture and sensitivity if any evidence of UTI on the urine dipstick

🔹protein:creatinine ratio if glomerulonephritis is suspected

Question 3

What is the NICE criteria for diagnosis of AKI?

Answer 3

Any of the following:
🔹rise in serum Cr of >=26umol/L / 48hrs

🔹>50% inc in serum Cr over past 7 days

🔹UO < 0.5ml/kg/hr for >6 hrs

Question 4

What is the RIFLE criteria? What is AKIN criteria?

Answer 4

RIFLE - Risk, Injury, Failure, Loss, End-stage renal disease
Uses serum Cr and UO to classify kidney injury
:::::
AKIN - uses stages 1-3 to classify AKI

Question 5

What is the KDIGO classification?

Answer 5

Staging of AKI

1 = Cr x 1.5-1.9 or >26umol/L / 48 hrs
:: = UO < 0.5 ml/kg/hr > 6hrs

2 = Cr x 2.0-2.9
:: = UO < 0.5 ml/kg/hr >12hrs

3 = Cr x >3.0 baseline or >353.6 umol/L
:: = UO < 0.3 ml/kg/hr >24hr or anuria > 12hrs

Question 6

What is the management of AKI?

Answer 6

Replace fluids
Hold nephrotoxics and review meds (NSAIDs, aminoglycosides, ACE-i, ARB, diuretics)
Treat underlying cause

Question 7

What are some early and late clinical manifestations of CKD?

Answer 7

Early:
- fatigue (toxins, anaemia from reduced EPO)
- polyuria/nocturia
- HTN
- puffiness/swelling - fluid retention

Late:
- reduced UO
- fluid overload
- uraemia - N+V, anorexia, metallic taste, pruritis
- Neuro - poor concentration, fatigue, seizures, coma
- CVD
- anaemia
- bone and mineral disease - bone pain, fractures, renal osteodystrophy
- metabolic acidosis - Kussmaul breathing, confusion, lethargy

Question 8

What causes anaemia in CKD?

Answer 8

• reduced EPO levels
• reduced erythropoiesis due to toxic effect of uraemia on bone marrow
• reduced iron absorption
• anorexia/nausea due to uraemia
• reduced red cell survival
• blood loss due to capillary fragility and poor platelet function
• stress ulceration => blood loss

Question 9

What is the management of mineral bone disease in CKD?

Answer 9

aim to reduce phosphate and PTH levels
- reduce dietary intake
- phosphate binders
- vitamin D
- parathyroidectomy in some cases

Question 10

How do ACE inhibitors have a renoprotective effect, particularly in diabetic nephropathy?

Answer 10

They cause dilation of the efferent glomerular arterioles, reducing glomerular capillary pressure and protecting the filtration barriers.