Renal Flashcards
For any pt with renal failure need to:
- assess degree of renal impairment
- make changes
- change to safer drug
- avoid nephrotoxics
Routine tests are:
- Plasma
* Urine
Plasma routine tests
- Creatinine
- Urea
- eGFR
Urine routine tests
- ACR/Albumin:creatinine ratio
- Osmolality
- specific gravity
- proteinuria/microalbuminuria
- haematuria
- mid stream urine
Creatinine
GFR = Cr Cl
• freely filtered by kidney
• product of protein metabolism
• 24hr urine collection
Limitations in urine collection/creatinine
- accuracy of urine collection
* time delay
Cockcroft & Gault equation
CrCl = [140-age]*IBW / Plasma Cr [umol/l]
* F
(F = 1.23 males, 1.04 females)
Limitations with Cockcroft & Gault equation
- assume average population data
- unsuitable for children and pregnancy
- renal fn must be stable
normal CrCl
120ml/min
normal CR
55 - 125umol/l
Metabolism in kidney impairment
- less vitD activated
- less insulit met
- less elimination API metabolites
eGFR 4 variables
age, sex, serum Cr, ethnic origin
Stages of eGFR
1 >90 Normal 2 60-89 Mild impairment 3a 45-59 3b 30-44 Mod 4 15-29 Severe 5 <15 End stage
eGFR units
ml/min/1.73m^2
Stage 1 G1
> 90 Normal
Stage 2 G2
60-89 Mild impairement
Stage 3A G3a
45-59
Stage 3B G3b
30-44 Mod
Stage 4 G4
15-29 Severe
Severe 5 G5
<15 End Stage
Urea - what is it
Breakdown product of protein metabolism
Uraemia
Urea in blood. >15mmol/l
High urea levels also in:
- dehydration
- excess protein intake
- haemorrhage
- severe infection
- muscle injury
Proteinuria
- ACR Albumin:Creatinin Ratio
- predictor of renal disease development
- predicts risk of AE
ACR
Albumin:Creatinine Ratio
uraemia in absorption
- vomiting diarrhoea, GI, oedema
- reduce Ca2+ absorption
- phosphate binders
uraemia in distribution
- reduce protein binding in drugs eg phenytoin
* reduce tissue binding in drugs eg digoxin
kidney impairment in metabolism
- VitD - less activation
- insulin - less met
- API metabolites - less elimination
dose adjustments - kidney impairment
- reduce dose
* increase dose interval
Loading dose adjustment - kidney impairment
none
Ideal drug in renal impairment
- wide therapeutic index
- liver eliminate
- not nephrotoxic
- not affected by changes in fluid balance, tissue or protein binding
kidney fn
- regulatory
- excretory
- endocrine
pre renal failure
less renal perfusion
intrinsic renal failure
damage to renal tissue
post renal failure
obstruction to urinary flow eg • Stones • structural eg tumour • nephrotoxicity • outside urinary tract eg ovarian tumour
Eg of urinary flow obstruction
- Stones
- Structural eg tumour
- nephrotoxicity
- outside urinary tract eg ovarian tumour
AKI reversible?
Yes
AKi secondary to?
decreased circulation (pre-renal failure)
AKI is
regulatory & excretory failure
AKI defined in terms of Cr
increased Cr ≥ 26 µmol/l
AKI defined in terms of urine output
decreased urine output to <0.5ml/kg/hr for >6hrs
Risk factors AKI
- Past AKI
- pre-existing CRF
- age >65yrs
- CCF
- PVD
- DM
- hepatic disease
AKI trigger factors
- sepsis/infection
- hypovolaemia (dehydration, bleeding)
- Hypotension
- drugs eg NSAIDs, ACEIs, ARBs, Diuretics
Drugs that could trigger AKI
- NSAIDS
- ACEIs
- ARBs
- Diuretics
AKI prevention
- avoid nephrotoxic drugs
- Monitor renal function for drugs known to cause renal impairment
- Review meds known to exacerbate AKI
Meds that exacerbate AKI
ACEI,
CRB,
diuretics
Signs of AKI
- Volume depletion
* Volume overload
Volume depletion signs of AKI
- Thirst
- Fluid loss ++
- Oliguria
- Dry mucosae
- low skin elasticity
- tachycardia
- hypotension
- low JVP
Volume overload (if left untreated)
- increased orthopnoea/fluid in lungs
- increased PND/ nocturnal dyspnoea
- SOA
- Oedema
- pulmonary oedema
- pulmonary crackles
PND
paroxysmal noctural dyspnoea
Treatment of AKI - Underlying causes
- Restoration of renal perfusion - IV fluids, blood
- Dialysis
- Review drug therapy - stop/withhold nephrotoxic drugs
AKI restoration of renal perfusion
- IV fluids eg NaCl 0.9%
* Blood
AKI Loop diuretics - what,
Furosemide IV
• doses 1-2g IV over 24hrs
AKI Loop diuretics - why
- produces diuresis, which decreases tubular cell metabolic demands & renal blood flow.
- increases renal prostaglandins/PG
- caution for dehydration
AKI Furosemide max rate IV
4mg/min (higher causes ototoxicity)
Ototoxicity
damage hear, hearing loss, balance disorders, ringing/tinnitus
Dopamine in AKI why
- renal vasodilation mediated through D1 receptors.
* increases renal perfusion
Dopamine in AKI dose
- low dose (2mcg/min)
* high dose >5mcg/kg/min can cause vasoconstriction
Antibiotics in AKI
if cause is infection
CKD
Chronic Kidney Disease
CKD what is it
- Regulatory, excretory & endocrine failure
- secondary to renal tissue damage
- subtle & slow onset
- irreversible by the time pt presents with symptoms
CKI reversible?
irreversible by the time pt presents with symptoms
ESRF
End Stage Renal Failure
ESRF treatment
- renal replacement therapy needed eg.
* dialysis or transplantation
Acute on Chronic Renal Failure
• sudden fast decline due to underlying cause eg dehydration. infection, drugs
Clinical manifestations of CKD
- Urinary symptoms
- Proteinuria
- Fluid retention
- Uraemia
- Anaemia
- electrolyte disturbance
- HYP
- muscle dysfn