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
who should be on EPO and what is the target Hb?
all patients with Hb<100 and adequate iron stores should be on EPO
target Hb = 100-120
benefits of EPO therapy?
better quality of life
less dyspnoea
reduced left ventricular hypertrophy
what to do if patient has poor response to EPO
check:
iron stores
inflammation
B12 + folate
PTH
aluminium
malnutrition
malignancy
why do CKD patients get renal osteodystrophy
kidneys activation of vitamin D reduced, vit D reduced, reduced calcium absorbed from gut, develop osteomalacia. in response to low Ca, PTH increases, causes osteitis fibrosa. PTH increases Ca and PO4 reabsorption from bone.
another name for osteitis fibrosa?
parathyroid bone disease
renal osteodystrophy treatment?
vegan diet (restrict phosphate)
phosphate binders
vit D therapy (alfacalcidol)
what are the consequences of hyperphosphataemia
vessel calcification
calciphylaxis
cardiovascular disease in ESRD - increased risk factors?
diabetes
hypertension
L vent hypertrophy
dyslipidaemia
malnutrition
what type of vessel calcification occurs in hyperphosphataemia? (explain)
medial calcification - calcification within the medial layer of vessel walls (makes vessels more visible in scans)
cardiovascular disease in ESRD - unique risk factors?
anaemia
hyperPTH
uraemia
hyperPO4
malnutrition in CKD - why!
nauseous if eat meat/dairy, protein levels decrease
decreased appetite
features of malnourished CKD patients
low albumin relating to inflammation/infection
malnourished patients do worse on dialysis
who should you refer to the renal clinic?
anyone with rapid increase in creatinine/hypertension
stage 3 CKD with hypertension/proteinuria/haematuria/rising creatinine
any stage 4/5 CKD suitable for treatment
options for dialysis?
haemodialysis - hospital 3 times a week, blood cleaned in machine for 4 hours.
peritoneal dialysis - uses space between guts and abdominal wall, fill with fluid for 4-6 hours, drained out and repeated. waste products drift into fluid.
transplantation - young, fit. history of malignancy is contraindication.
when do you start dialysis?
creatinine clearance 9-14
