renal function Flashcards
what are the main functions of the kidney
excretory
endocrine
regulatory
metabolism
how does the kidney play a role in excreting
excretes waste products and drugs
how does the kidney play a endocrine role
erythropoietin production - stimulates RBC prod. in bone marrow
renin production
prostaglandin production
how does the kidney play a regulatory role
fluid volume control and composition
BP regulation
blood pH regulation
how does the kidney play a role in metabolism
vitamin d metabolism
what are routine tests for assessing renal function
plasma
urea
eGFR
urine
what does the blood test for creatinine show
(CrCl), increased in decreased function because it is not being excreted (55-125 umol/L)
what are the limitations of the Cockcroft and gault equation
assumes average population data
unsuitable for kids and pregnancy
renal function must be stable
what shows up in plasma blood tests
creatinine
urea
eGFR
what does the blood test for urea show
nitrogenous breakdown product of protein metabolism - usually excreted - <15mmol/L = uraemia - not specific
what else can raise urea levels in the blood
dehydration
muscle injury
infection
haemorrhage
excess protein intake
what does eGFR mean
calculated using CKI-EPI as a local lab calc
what are the stages of renal impairment and the matching eGFR
normal - >90
mild - 60-89
mild/mod - 45-59
mod/sev - 30-44
severe - 15-29
end stage - <15
what shows up in urine tests when checking renal function
osmolality
specific gravity
haematuria
mid-stream urine
albumin - creatinine ratio
what does the osmolality test show about renal function
high particle conc = high osmolality
what does the specific gravity test show about renal function
solute concentration, more = higher gravity
what does the haematuria test show about renal function
blood in the urine
what does the MSU test show about renal function
UTI
what does the albumin:creatinine ratio test show about renal function
predictor of renal disease development albumin should be in blood not urine (alb/cr)
what does the proteinuria test show about renal function
albumin should be in blood not urine
what are the effects on drug absorption in CKD
uraemia reduces - D&V, GI oedema
red. calc absorption - less vit d activation
what are the effects on drug distribution in CKD
less protein and tissue binding
what are the effects on drug metabolism in CKD
○ Less vitamin D metabolism (less calcitriol production) = Less calcium absorption from gut and kidneys
○ Less insulin metabolism
Less elimination of pharmacologically active metabolites
what are the effects on drug excretion in CKD
○ Less excretion
○ Dose adjustments: Lower dose and/or increased dose interval
○ NO adjustment to LOADING DOSES
what characteristics do drugs used in renal impairment ideally need to have
wide therapeutic index
eliminated via liver
not nephrotoxic
not affected by changes in fluid balance. tissue or protein binding
