Chronic Kidney Disease and Transplantation Flashcards
what are the features nephrotic syndrome?
- presence of proteinuria >3g in 24 hour
- oedema
- hyperlipidaemia
- lower BP
what causes oedema in nephrotic syndrome?
due to loss of hydrostatic pressure so if the liver function is good then liver might not be as bad (albumin is a good indicator).
albumin creatinine ratio 70
protein creatinine ratio 100
where is the defect typically in a patient with nephrotic syndrome?
GBM endothelial or podocyte
what are the features of nephritic syndrome?
- less oedema than nephrotic syndrome
- proteinuria <3g in 24hour
- haematuria (usually microscopic)
- higher BP
- low or normal albumin so fluid is intravascular so increased BP
why is there proteinuria but not haematuria in nephritic syndrome?
GBM is negatively charged so cannot allow protein through so less proteinuria but still haematuria
what is usually the defect in a patient with nephritic syndrome?
usually inflammatory condition
give examples of causes of nephrotic syndrome?
- IgA nephropathy (can present as nephritic)
- FSGS (focal segmental glomerular sclerosis) common in HIV patients
- minimal change disease (most common in children)
- membranous nephropathy (most common in adults)
- amyloidosis
give examples of causes of nephritic syndrome?
- good pastures
- lupus (membranous nephropathy secondary to lupus)
- glomerulonephritis
- vasculitis
define chronic kidney disease?
sustained, irreversible kidney damaged (longer than 6 weeks)
describe how eGFR is measured?
NICE guidelines-blood tests taken 90 days apart
estimated GFR using creatinine
cystatin C
urea
describe the formula use to calculate eGFR?
- MDRD (no longer used)
- EPI (ml/min/1.73m2). need body weight and height to calculate SA, depends on factors such as gender, age, race, serum creatinine)
what is the role of ACE inhibitors in patients with CKD?
they help especially with proteinuria
they are contraindicated in pregnancy, renal artery stenosis
why are older people more likely to have CKD?
drugs
co-morbidities
ageing process
GFR-go downs per 1ml per year after 45
what diseases can cause CKD to go undetected?
amyloidosis or multiple myeloma as proteins other than albumin being produced so won’t get picked up
who should be referred to a renal clinic?
patients G3b or below
what are the signs and symptoms of CKD?
- oedema-due to fluid overload and RAAS causing increased sodium and volume.
- increased BP
- metabolic acidosis
describe salt reabsorption in the kidney and what drugs act at each location?
- 60% in PCT (carbonic anhydrase inhibitor, manntiol)
- 30% LoH (furosemide=IV and oral, bumetanide=oral)
- 10% DCT (thiazides, aldosterone, spironolactone, amiloride- these don’t work when GFR<45)
- CD <1% - ADH
- diuretic resistance-increase dose
what are the options for treating CKD?
- conservative care
- renal replacement therapy
what are the methods of renal transplant therapy?
- dialysis (haemodialysis, peritoneal)
- transplant (deceased either heart beating or non heart beating OR living (related, non related, altruistic)
define kidney failure?
simply a reduction in kidney function. It is identified from; a decrease in urine output, increase in serum creatinine, decrease in estimated eGFR.
what can kidney failure be categorised based on timescale?
AKI- sudden decrease in kidney function over days or weeks
CKD- persistent decline in kidney function over longer time
acute on chronic kidney failure - sudden decrease in kidney function in someone with CKD
end stage kidney disease-insufficient kidney function to maintain life without renal replacement therapy
what type of kidney failure is reversible and what is non reversible?
AKI/acute on chronic have the potential to restore kidney function
chronic /end stage -not reversible
what is used to determine the severity of AKI?
RIFLE classification
what is used to determine the severity of CKD?
GFR
Stage 1- normal GFR, applied to people with abnormality of kidney but still working normally eg autosomal dominant polycystic kidney disease or someone with diabetes and microalbuminaemia
Stage 3 is split into 2 groups important due to risk of progressive renal failure greater in patients of 3b
how can kidney failure be classified based on site of injury?
pre renal - decreased blood flow either because of fixed obstruction (renal artery stenosis) or decreased circulating volume or blood pressure
renal - injury within kidney
post renal - obstruction between pelvis and urethra, it has to affect both kidneys to cause kidney failure.
describe the stages in CKD severity?
stage 1 - normal GFR stage 2 - 60-89ml/min stage 3a - 45-59ml/min stage 3b - 30-44ml/min stage 4 - 15-29ml/min stage 5 - <15 ml/min or RRT
what are the stages in the RIFLE criteria for AKI?
risk injury failure loss end stage kidney disease
what are the causes of pre renal failure?
True hypovolaemia (history of volume loss eg diarrhea, vomiting, burns, haemorrhag) Relative hypovolaemia (heart failure, septic shock, hepatorenal failure) Renovascular disease
what are the clues that point towards pre renal failure?
Clinical history and examination
- Cause for volume depletion
- Signs of hypovolaemia (tachycardia, hypotension esp. postural hypotension
Clues to renovascular disease
- Atherosclerotci vascular disease
- Hypertension
- Vascualr bruit
- Deteriorting renal function after ACE inhibitors or ARB
what medications can cause pre renal failure?
angiotensin 2 blockers
prostaglandin synthesis blockers
describe how ACE inhibition can cause volume depletion?
afferent arteriole pressure is generated by flow and efferent arteriole pressure is generated by resistance and usually is equal. the GFR depends on the pressure diffrence
if there is decreased flow to the afferent arteriole the pressure difference is maintained by increased resistance which is angiotensin 2 mediated vasoconstriction and GFR is maintained however if there is decreased flow to the afferent arteriole and the patient uses ACE/ARB then the pressure difference won’t be maintained and GFR will decline
how can NSAID use and ACE use lead to reduction in GFR?
pressure in afferent arteriole is maintained by pressure generated by flow which is mediated by prostaglandins causing vasodilation and pressure in efferent arteriole is generated by resistance. NSAIDs block prostaglandin synthesis and vasoconstriction results in decreased flow but the pressure is maintained by increasing resistance in efferent arteriole mediated by angiotensin 2 but with ACE/ARB the efferent arteriole cannot maintain pressure difference and subsequently there is a decreased GFR