clinical renal failure & tests Flashcards
defining factor of renal failure
reduction in kidney function = low GFR
normal GFR = 100ml/min
how can you tell if a patient has kidney failure
blood tests
- creatinine (made from muscles) would be high
- urea
factors affecting eGFR
- weight (muscle mass)
- age
- gender
what is creatinine a measure for
how much muscle waste is produced and how well the kidneys get rid of that waste product
limitations of eGFR
- inaccurate if muscle mass is unusually high or low
- only valid for patients in steady-state
define acute kidney injury
- sudden rapid reduction in GFR
- happens over days/weeks
- usually reversible
describe causes of pre-renal acute kidney injury and effects
(70% due to non renal causes)
- low BP
- dehydration (signs of JVP)
- septic shock
- hemorrhage
usually low initial urinary output high creatinine hyperkalemia high phosphate may have low calcium
treatment for pre-renal acute kidney injury
fix underlying problem - rehydrate - treat bleeding - fix heart etc
describe renal acute kidney injury and effects on blood test
= acute tubular necrosis (mainly due to pre-renal)
- persistant oliguria & renal failure after correction of pre-renal cause
- may take 4-6 weeks to recover
high creatinine
low urine output
hyperkalemia
treatment for renal acute kidney failure
maintain normal BP
treat the underlying problem
if kidneys keep getting worse = dialysis
describe polyuric phase in renal acute kidney failure recovery phase
- tubules cant concentrate (urine)
- up to 20L urine a day
- need IV fluids till recovers
when creatinine levels get back to normal they should be able to concentrate their urine again and be back to normal
apart from ATN what is another cause of renal acute kidney failure
glomerulonephritis (inflammation of glomerular)
- rapid damage to filtering units
- presents with blood and protein in the urine
- diagnosed by renal biopsy
describe causes of post-renal acute kidney injury and effects
- kidney stones
- tumour
- prostate hypertrophy
- urinary retention
can identify by an ultrasound, commonly showing a blockage
describe chronic kidney failure and blood tests
- happens over months/years
- gradual decline in renal function
- irreversible
elevated creatinine
elevated urea
usually normal urine output
causes of chronic kidney disease
- diabetes
- glomerulonephritis
- hypertension
what happens during chronic kidney failure
gradual increase in creatinine due to underlying disease. This causes scarring of glomeruli and interstitium
symptoms of chronic kidney failure
- none in early stages (asymptomatic)
- usually found on blood tests
- urine output normal
uremia = symptoms of kidney failure
uremic signs
- nausea/vomiting
- itchiness
- SOB
- coma
- Swelling
- anorexia
signs of chronic kidney failure
- hypertension
- oedema
- pulmonary oedema
- raised JVP
how is chronic kidney failure diagnosed and what are the results
routine blood tests
- increased urea
- increased creatinine
- decreased GFR
- low Hb
why do patients with chronic kidney failure become anaemic
kidneys produce erythropoietin which allows the bone marrow to produce RBC
Therefore kidney failure means erythropoietin isn’t being made and neither is RBCs
what are the consequences of chronic kidney failure
- inability to metabolize vitamin D, therefore low calcium
- elevated serum phosphate
- hyperthyroidism
- decreased bone health
- calcium and phosphate buildup in BVs
- hyperkalemia –> fatal arrhythmias
main treatment for chronic kidney failure
- prevent deterioration of renal function by hypertension
e. g. prescribe ACE inhibitor
