Chem Path - Acute and Chronic Kidney Flashcards
Acute Kidney Injury
What needs to be measured?
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
Pre-Renal
What is the pathophysiology?
↓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
Pre-Renal
What are some generalised causes?
Low-flow states - Heart failure and liver failure
True volume depletion - massive dehydration
Hypotension - due to sepsis or otherwise
Pre-Renal
What are some specific causes?
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)
Intrarenal
Direct tubular injury causes?
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
Intrarenal
Renal Inflammation
Glomerulonephritis
Vasculitis
Intrarenal
Infiltration
Amyloidosis
Lymphoma
Myeloma-related lymphoid disease
CKD
Staging
1-5 1 is normal 2 is mild decrease in GFR 3 is moderate 4 is severe 5 is end stage kidney failure
CKD
Stage 1
> 90
CKD
Stage 2
60-90
CKD
Stage 3
30-60
Think 3 - 30
CKD
Stage 4
15-30
CKD
Stage 5
<15 or dialysis
CKD
Marker of prognosis
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.
Causes of CKD
Diabetic nephropathy Atherosclerosis causing renal artery stenosis Hypertension Chronic glomerulonephritis Infective or obstructive uropathy
Consequences of CKD
acid-base
Renal Acidosis
Failure to excrete protons
Rx give bicarb
Hyperkalaemia
Consequences of CKD
Hormones
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
Consequences of CKD
CV
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
