chronic kidney disease W2 Flashcards
case: 56 yr old man.
tiredness and itchy skin
BP 180/110
high urea
high creatinine
high potassium
low bicarbonate
low haemoglobin
low calcium
high phosphate
explain these results
poor tubule function = low bicarbonate, high potassium, high creatinine
fluid retention = hypertension
diagnostic definition of chronic kidney disease
GFR of <50ml/min for >90 days
causes of CKD?
most common = diabetes, hypertension
rarer = glomerulonephritis, cystic kidney disease, renovascular disease
how do we estimate kidney function?
serum creatinine
creatinine clearance
isotope GFRs
formulae (often used)
what is a normal GFR?
125ml/min/1.73m^2
what formulae do we currently use to estimate GFR
MDRD or CKD-EPI equation
(CKD-EPI Cystatin C equation rarely used but more accurate)
stages of CKD?
creatinine clearance (~GFR)
stage 1 = normal = 120-90
stage 2 = early CRF = 90-60
stage 3 = moderate CRF = 60-30
stage 4 = pre-ESRD = 30-15
stage 5 = ESRD = 15-0
CRF? ESRD?
chronic renal failure
end stage renal disease
when are you put on a renal transplant list!
GFR<15 (stage 5/ESRD)
how to prevent progression of CKD
control blood pressure (RAS inhibition - ACE inhibitors)
reduce proteinuria (RAS inhibition)
if diabetes, optimise glycaemic control
SGLT2 inhibitors
when do you have to worry about stage 1/2 CKD? (GFR>60)
when albuminuria is severely increased (>300mg/g or >30mg/mmol)
is proteinuria a marker or cause of progressive renal disease
both!!
how does proteinuria cause chronic interstitial fibrosis
proteinuria taken up into tubular cells, processed by lysosomes into amino acids, taken into tubular capillaries. system gets overloaded in patients with large amounts of proteinuria. cell gets overloaded and dies. fibroblasts/macrophages try remove cell, causes scarring (interstitial fibrosis)
how do ACE inhibitors decrease proteinuria
cause efferent arteriole vasodilation. drop pressure in glomerulus therefore decrease amount of protein passing through.
toxic drugs to the kidney?
NSAIDs/contrast/gentamicin
phosphate enemas
drug dosing and CKD?
lower doses of blood pressure tablets, antimicrobials etc
especially chemotherapy agents
if in doubt check BNF!!
hypertension and CKD?
cause and consequence of CKD
BP treatment goals for CKD?
normal - 130/80
DM/proteinuria - 125/75
treatment of hypertension in CKD?
low salt diet
lifestyle modifications (exercise/alcohol/smoking)
BP meds eg ACEi
high potassium in CKD - when does this occur and how is it managed?
common once GFR<25
give dietary advice
give potassium binders (sodium zirconium) but expensive - only use short term
what is much acidosis in CRF due to? why?
animal protein in food
because inability to acidify urine in CKD
phosphate/sulphates/other anions
how to treat acidosis in CKD?
replace with NaHCO3 (sodium bicarbonate)
but beware fluid overload
aim to keep serum bicarbonate >22
anaemia in CKD definition?
Hb<12 in males
Hb<11 in females
anaemia in CKD features
generally normochromic normocytic anaemia
decreased response of EPO to a hypoxic stimulus (kidneys) and decreased red cell survival in most patients
