Chem Path - Acute and Chronic Kidney

Question 1

Acute Kidney Injury

What needs to be measured?

Answer 1

Creatinine and Urine Output

This will allow you to stage the severity of the disease, which will influence your management.

Stages 1-3 (mild, mod, severe)

1 - ↑Cr by 1.5x-2x, urine output <0.5ml/kg/hr for 6 hrs
2 - ↑Cr by 2x-3x, urine output <0.5ml/kg/hr for 12 hrs
3 - ↑Cr by >3, urine output <0.5ml/kg/hr for 24 hrs

Question 2

Pre-Renal

What is the pathophysiology?

Answer 2

↓Renal perfusion

Can be from generalised (sepsis) or specific causes (renal ischaemia)

Cannot be ‘pre-renal’ AKI if cause is due to structural abnormality such as acute tubular necrosis

Question 3

Pre-Renal

What are some generalised causes?

Answer 3

Low-flow states - Heart failure and liver failure
True volume depletion - massive dehydration
Hypotension - due to sepsis or otherwise

Question 4

Pre-Renal

What are some specific causes?

Answer 4

Selective renal ischaemia - renal artery stenosis - caused by atherosclerosis.

DRUGS
ACEI (lead to loss of efferent arteriole tone)
NSAIDs and Calcineurin inhibitors (decrease afferent arteriole dilation)
Diuretics (hypoperfusion)

Question 5

Intrarenal

Direct tubular injury causes?

Answer 5

Ischaemia - causes tubular cell necrosis, forming a ‘plug of debris’, causing AKI

Endogenous - myoglobin - caused by rhabdomyolysis and looks brown/black. Important to check CK and hyperkalaemia
Immunoglobulins light chains can also cause damage - multiple myeloma

Exogenous - Contrast, Drugs - 3As
Aminoglycosides
Amphotericin
Acyclovir

Question 6

Intrarenal

Renal Inflammation

Answer 6

Glomerulonephritis

Vasculitis

Question 7

Intrarenal

Infiltration

Answer 7

Amyloidosis
Lymphoma
Myeloma-related lymphoid disease

Question 8

CKD

Staging

Answer 8

1-5
1 is normal
2 is mild decrease in GFR
3 is moderate
4 is severe
5 is end stage kidney failure

Question 9

CKD

Stage 1

Answer 9

> 90

Question 10

CKD

Stage 2

Answer 10

60-90

Question 11

CKD

Stage 3

Answer 11

30-60

Think 3 - 30

Question 12

CKD

Stage 4

Answer 12

15-30

Question 13

CKD

Stage 5

Answer 13

<15 or dialysis

Question 14

CKD

Marker of prognosis

Answer 14

Both GFR and albumin:creatinine ratio are markers of prognosis. Lower GFR and higher albumin:Cr means worse outcomes.

Albumin thought to increase with persistent acidosis (which is caused by CKD) and inflammation, therefore higher albumin is WORSE.

Question 15

Causes of CKD

Answer 15

Diabetic nephropathy
Atherosclerosis causing renal artery stenosis
Hypertension
Chronic glomerulonephritis
Infective or obstructive uropathy

Question 16

Consequences of CKD

acid-base

Answer 16

Renal Acidosis

Failure to excrete protons
Rx give bicarb

Hyperkalaemia

Question 17

Consequences of CKD

Hormones

Answer 17

Anaemia of Chronic (renal) disease
Loss of EPO-producing cells, stage 3-4 CKD
Rx: EPO stimulating agents

Bone Disease
2ndary Parathyroid due to loss of 1a-hydroxylase

Rx
Suppress PTH with Cinacalcet (pretends to be Ca and switches PTH off)
Reduce phosphate with diet and phosphate binders
↑Vit D receptor sensitivity - 1a-calcidol, paracalcitol

Correction can result in adymanic bone disease or renal osteodystrophy - bone disease due to kidneys

Question 18

Consequences of CKD

CV

Answer 18

Vascular calcification

Calcification caused by kidney disease - makes cardiovascular risk much higher.

Uraemic cardiomyopathy

Thought that uraemia may cause LVH, causing heart failure

Uraemia will eventually cause death