chronic kidney disease and renal failure Flashcards
what are the roles of the kidneys in health?
homeostatic function:
Electrolyte balance
Acid-base balance
volume homeostasis
excretory function: nitrogenous waste hormones peptides middle sized molecules salt and water
endocrine function:
erythropoietin
1 alpha-hydroxylate vitamin D
glucose metabolism:
gluconeogenesis
insulin clearance
what happens to the functions of the kidneys kidney failure?
homeostatic function: increased potassium decreased bicarbonate decreased pH increased phosphate salt and water imbalance
excretory function:
increased urea
increased creatinine
decreased insulin requirement
endocrine function:
decreased calcium
increased parathyroid hormone
anaemia
glucose metabolism:
no gluconeogenesis or insulin clearance
also increased cardiovascular risk
how does kidney failure present?
alll depends on the rate of deterioration
and the cause of kidney failure
some symptoms: weakness loss of appetite pale poor skin turgor tachycardia tachypnoea lethargy
why might someone be tachypneic with normal oxygen sats and clear lungs on auscultation?
Kussmaul respiration - fast, deep breaths that occur in response to metabolic acidosis.
lack of bicarbonate production in the failing kidneys leads to metabolic acidosis
so you hyperventilate to clear more CO2, increasing pH to reverse the acidosis
what happens to urea, creatinine, sodium, potassium and haemoglobin levels in kidney failure?
Urea: increases Creatinine: increases Sodium: depends on diet but may drop Potassium: increases Haemoglobin: decreases
how do you image kidneys?
best way is ultrasound
look for size, obstruction etc
what happens to salt and water balance in kidney failure?
Kidney failure tends to REDUCE secretion of salt and water leading to:
Hypertension
Oedema
Pulmonary oedema
BUT Salt and water loss may be seen in tubulointerstitial disorders – damage to concentrating mechanism
& hypovolemia may be the cause of AKI.
can be the cause or a symptom
does hyponatraemia mean reduced total body sodium?
not necessarily, it could also be excess water
what is the bicarbonate equation?
HCO3- + H+
->
why does kidney failure cause metabolic acidosis?
decreased kidney function leads to less excretion of hydrogen ions
that means there are more hydrogen ions leading to lowered pH
it also means that potassium ions will be stopped from being increased (due to the increased positive charge in the cells) so it causes hyperkalaemia
this also causes anoerxia and muscle catabolism
why does kidney failure cause hyperkalaemia?
causes:
decreased distal tubule potassium secretion
acidosis
symptoms (depending on chronicity):
cardiac arrythmias
neural and muscular activity
vomiting
what happens to an ECG in kidney failure?
Peaked T waves
P wave
- broadens
- reduced amplitude
- disappears
QRS widening
Heart block
Asystole
VT/VF
how does kidney failure cause anaemia?
erythropoietin is produced in the kidney
this is needed to make red blood cells
how does linden failure effect vitamin D
1-alpha- hydroxylase is found in the kidney
this is vital in producing functional vitamin D (1-25-dihydroxy-cholecalciferol)
so without vitamin D, there is less intestinal absorption of calcium
leading to hypocalcaemia
low levels of calcium will also mean there is less negative feedbalk on parathyroid hormone.
chronically this causes hyperparathyroidism
also phosphate retention due to chronic renal failure leds to low vitamin D and hypocalcaemia
what happens to the heart?
big increase in cardiovascular risk
caused by anaemia and hypocalcaemia
Major predictor of end stage renal failure is CKD
BUT
Major outcome for a patient with CKD is cardiovascular disease
.e. a patient with CKD is more likely to die from cardiovascular disease than end stage renal failure.
Standard cardiovascular risk:
Hypertension
Diabetes
Lipid abnormalities
Additional risks:
Inflammation
Oxidative stress
Mineral/bone metabolism disorder
how do the NICE guidelines classify kidney failure?
using GFR and proteinuria (albumin:creatinine ratio)
there’s a table
