renal Flashcards
NICE criteria for AKI
- rise in creatinine of >25micromol/L in 48hrs
- rise in creatinine of >50% in 7 days
- urine output of <0.5ml/kg/hour for >6hrs
8 risk factors for AKI
- CKD
- HF
- DM
- liver disease
- older age (>65)
- cognitive impairment
- nephrotoxic medications - NSAIDs, ACE-i
- use of contrast medium i.e. CT
categories for causes of AKI
pre-renal
renal
post-renal
3 pre-renal causes of AKI
inadequate blood supply:
- dehydration
- hypotension
- heart failure
3 renal causes of AKI
intrinsic disease:
- glomerulonephritis
- interstitial nephritis
- acute tubular necrosis
4 post-renal causes of AKI
obstruction to urine outflow:
- kidney stones
- masses (cancers)
- ureter/urethral strictures
- enlarged prostate, prostate cancer
investigations in AKI
urinalysis
US KUB
urinalysis results and what they suggest
- leucocytes and nitrites suggest infection
- protein and blood suggest acute nephritis (or infection)
- glucose suggests diabetes
treatment of AKI
treat underlying cause:
- fluid rehydration (pre-renal)
- stop nephrotoxic meds
- relieve obstruction (post-renal) e.g. insert catheter
4 complications of AKI
- hyperkalaemia
- fluid overload, heart failure and pulmonary oedema
- metabolic acidosis
- uraemia -> encephalopathy, pericarditis
6 causes of CKD
- diabetes
- hypertension
- age-related decline
- glomerulonephritis
- polycystic kidney disease
- medications: NSAIDs, PPIs, lithium
5 risk factors for CKD
- older age
- hypertension
- diabetes
- smoking
- use of medicines which affect kidneys
8 signs/symptoms of CKD
can be asymptomatic
- pruritis
- loss of appetite
- nausea
- oedema
- muscle cramps
- peripheral neuropathy
- pallor
- hypertension
investigations to diagnose CKD
U&E - eGFR
measured twice, 3 months apart
investigations for CKD
- eGFR (U&E)
- urine albumin:creatinine ratio >3mg/mmol
- haematuria (urine dip) 1+
- renal USS
staging of CKD
G and A scores:
- G score based on eGFR
- A score based on Albumin:creatinine ration
G score for CKD
G1 - eGFR >90 G2 - eGFR 60-89 G3a - eGFR 45-59 G3b - eGFR 30-44 G4 - eGFR 15-29 G5 - eGFR <15 (end-stage renal failure)
A score for CKD
A1 - ACR <3mg/mmol
A2 - ACR 3-30mg/mmol
A3 - ACR >30mg/mmol
diagnostic criteria for CKD
eGFR <60 or proteinuria
5 complications of CKD
- anaemia
- renal bone disease
- cardiovascular disease
- peripheral neuropathy
- dialysis related problems
4 criteria for specialist referral in CKD
- eGFR <30
- ACR >70mg/mmol
- accelerated progression: decrease in eGFR of 15 or 25% or 15ml/min in 1 year
- uncontrolled HTN despite 4+ antihypertensives
4 main aims of CKD management
- slow progression
- reduce risk of CVD
- reduce risk of complications
- treat complications
3 management approaches to slow progression of CKD
- optimise diabetic control
- optimise HTN control
- treat glomerulonephritis
lifestyle modifications to reduce risk of complications from CKD
- exercise
- maintain healthy weight
- stop smoking
- dietary advice regarding: phosphate, sodium, potassium and water
which medication should be prescribed in CKD to prevent CVD
atorvastatin 20mg
4 complications of CKD and associated treatments
- metabolic acidosis - oral sodium bicarbonate
- anaemia - iron supplementation and erythropoietin
- renal bone disease - vitamin D
- end stage - dialysis or renal transplant
HTN treatment in CKD and when given
ACE-i (renoprotective)
- diabetes + ACR >3
- HTN + ACR >30
- anyone with ACR >70
aims of HTN tx in CKD
maintain BP <140/90 or <130/80 if ACR >70
monitoring necessary in HTN management in CKD
serum potassium
ACE-i and CKD cause hyperkalaemia
pathophysiology of anaemia in CKD
healthy kidney cells produce erythropoietin which stimulates production of RBC
CKD = decreased kidney function = less RBC produced
why are blood transfusions not recommended for management of anaemia in CKD
can sensitise immune system (allosensitisation) so transplanted organs are more likely to be rejected
management of anaemia in CKD
‘anaemia of chronic disease;
- treat iron deficiency first (IV iron or oral iron)
- exogenous erythropoietin
3 features of renal bone disease
- osteomalacia (softening of bones)
- osteoporosis (brittle bones)
- osteosclerosis (hardening of bones)
x-ray changes in renal bone disease
- osteosclerosis (hardening) of both ends of vertebra = denser white appearance
- osteomalacia (softening) in centre of vertebra = less white appearance
pathophysiology of renal bone disease
- reduced phosphate excretion => high serum phosphate
- low active vit D => reduced calcium absorption from intestines and kidneys
- secondary hyperparathyroidism (PT glands react to low calcium and high phosphate by excreting more PTH) => increased osteoclast activity
why does osteomalacia occur in renal bone disease
increased turnover of bones without adequate calcium supply
why does osteosclerosis occur in renal bone disease
osteoblasts respond by increasing activity to match osteoclasts (due to secondary hyperparathyroidism)
new tissue is not properly mineralized due to low calcium
management of renal bone disease
- active forms of vitamin D (alfacalcidol, calcitriol)
- low phosphate diet
- bisphosphonates to treat osteoporosis
5 indications for acute dialysis and mnemonic
AEIOU
- Acidosis (severe, not responding to tx)
- Electrolyte abnormalities (severe and unresponsive hyperkalaemia)
- Intoxication (overdose of certain meds)
- Oedema (severe and unresponsive pulmonary oedema)
- Uraemia symptoms (seizure, reduced consciousness)
indications for long term dialysis
- end stage renal failure (CKD stage 5)
- acute indications continuing long term
3 main options for long-term dialysis
- continuous ambulatory peritoneal dialysis
- automated peritoneal dialysis
- haemodialysis
what is peritoneal dialysis
special dialysis solution added to the peritoneal cavity. ultrafiltration from blood to dialysis solution occurs through the peritoneal membrane (natural filtration membrane). leftover fluid with waste products filtered from blood then removed and clean dialysis fluid replaced and process repeats.
types of peritoneal dialysis
- continuous ambulatory peritoneal dialysis
- dialysis solution in peritoneum at all times
- different regimes e.g. 2L fluid inserted and changed 4x day - automated dialysis
- dialysis occurs overnight
- machine continuously replaces fluid overnight, takes 8-10hrs
5 complications of peritoneal dialysis
- bacterial peritonitis - infusion of glucose solution predisposes to bacterial growth
- peritoneal sclerosis
- ultrafiltration failure - starts to absorb dextrose in solution making filtration gradient less effective
- weight gain - absorb carbohydrates in solution
- psychosocial effect
what is haemodialysis
patients have blood filtered by haemodialysis machine e.g. 4hrs a day 3x week
need good access to blood supply
types of vascular access for haemodialysis
- tunnelled cuffed catheter
2. AV fistula
what is a tunnelled cuffed catheter for dialysis
- tube inserted into subclavian or jugular vein with tip sitting in SVA or RA
- 2 lumens (enter/exit)
- Dacron cuff ring surrounding catheter promotes healing and adhesion to make more permanent and protect against infection
what is an AV fistula
- artificial connection between an artery and a vein
- bypasses capillary system allowing high pressure blood from artery into vein
- permanent, large, easy access to blood supply
3 typical sites for AV fistula (vessels)
- radio-cephalic
- brachio-cephalic
- brachio-basilic
complications of tunnelled cuffed catheter in haemodialysis
infection
blood clots
time-frame for AV fistulas from formation to usage
requires surgical operation
4 week - 4 month maturation (needs to be made in advance of when dialysis is required)
signs to look for with AV fistula on examination
- skin integrity
- aneurysms
- palpable thrill
- stereotypical ‘machinery murmur’ on auscultation
6 complications of AV fistula
- aneurysm
- infection
- thrombosis
- stenosis
- STEAL syndrome
- high output heart failure
what is STEAL syndrome
inadequate blood supply to limb distal of AV fistula - fistula ‘STEALs’ blood from distal limb causing distal ischaemia
how does AV fistula cause high output cardiac failure
blood flows very quickly from arterial to venous system
rapid return of blood to the heart which increases pre-load to the heart which leads to hypertrophy of heart muscle and heart failure
how are patients and donors matched for kidney transplant
based on human leucocyte antigen (HLA) type A, B and C on chromosome 6
kidney transplant procedure
patients own kidneys left in place
donor kidneys blood vessels connected with patients pelvic vessels (external iliac)
donor ureter anastomosed directly with patients bladder
donor kidney placed anterior in abdomen and can be palpated in iliac fossa
typical scar for kidney transplant
‘hockey stick scar’
immunosuppressant regime after kidney transplant
tacrolimus
mycophenolate
prednisolone
can also use: cyclosporine, sirolimus, azathioprine
transplant-related complications from kidney transplant
- transplant rejection
- transplant failure
- electrolyte imbalance
immunosuppressant-related complications from kidney transplant
- ischaemic heart disease
- T2DM
- infection risk
- unusual infections: PCP, PJP, CMV, TB
- non-Hodgkin lymphoma
- skin cancer (SCC)
definition of nephritis
generic term: inflammation of the kidneys
not a diagnosis
what is nephritic syndrome
group of symptoms not a diagnosis
fit a clinical picture of having kidney inflammation
does not give diagnosis or underlying cause
features of nephritic syndrome
- haematuria (microscopic or macroscopic)
- oliguria (reduced UO)
- proteinuria (<3g in 24hrs)
- fluid retention
criteria for nephrotic syndrome
- peripheral oedema
- proteinuria >3g in 24hrs
- serum albumin <25g/L
- hypercholesterolaemia