Kidney diseases and functions Flashcards
Name the function of the kidneys
- Homeostasis; regulates and maintains the the body states at various-different parameters
- > elimination of waste
- > water homeostasis
- > acid base homeostasis; need to pass enough enough H+ ions to prevent acidosis
- > electrolyte homeostasis
- > blood pressure control
- Excretion of drugs and drug metabolites
- Metabolic/ Endocrine
- > synthesis of hormones; Vitamin D, Erythipoietin, Renin
How would you measure kidney function?
the serum creatinine which is the traditional measure
- influenced by gender, ethnicity, age, body mass, diet
What does the graph for GFR vs plasma creatinine look like?
- as kidney function declines, the creatinine levels increase (GFR decreases)
- not sensitive to small changes
- non-linear relationship to kidney function
- doesn’t take long-term changes into account
How would you estimate the GFR?
- calculate from creatinine, age, gender, ethnicity
- better reflection of kidney function
- best measure for use in stable renal function
Is CKD irreversible or reversible?
irreversible and tends to progress
How many stages of CKD are there?
CKD 1-5
stage 5 is the worst it shows kidney failure of levels of 0-15 eGFR
CKD 4- Severe decrease in GFR ; 15-29; feeling tired and insulin doses and drug tablets
CKD 3- moderate CKD; 30-59
CKD2- kidney damage but mild; 60-89
CKD 1- kidney damage but normal GFR; >90
What occurs with CKD 5?
- end stage renal failure
- insufficient renal function to sustain life/health
- > haemodialysis
- > peritoneal dialysis
- > kidney transplantation
death
- there are renal replacement therapies are essential to prevent progression of kidney failure7
Who has CKD?
- common
- most of it unrecognised
- diabetes and renovascular disease lead to CKD and most common
- more common with older age
What are the risk factors for CKD?
- increased age
- hypertension (highest risk)
- diabetes
- smoking
- poor education
Causes of CKD
- systemic diseases; diabetes, hypertension, atherosclerotic disease
- immune mediated diseases; IPA nephropathy
- infectious diseases; HIV, HBV, HCV, TB
- genetic diseases; polycystic kidneys
- arterial disease; atherosclerosis
- obstruction; tumours, stones, fibrosis
With chronic glomerulonephritis, what happens to the glomeruli and tubules?
sclerosed glomeruli and atrophied tubules
What is the pathology of CKD?
- thickening of basement membrane; capillary walls become weak and bleed and leak protein; slow blood flow
- mesangial expansion
- > hyperglycaemia stimulates increased matrix production by mesengial cells
- > stimulation of TGF-beta release
- glomerulosclerosis
- > due to intraglomerular hypertension or ischaemic damage
- high levels of sugarcane also make vessels to become narrow and clogged
Explain the vascular disease- renal artery stenosis
- low blood flow
- consequence of poor diet and diabetes
- both or one of the arteries leading to the kidneys becomes narrowed
- cant use an ACE inhibitor
- we want to constrict the afferent arterial to maintain BP and glomerular pressure
List the complications of CKD
- anaemia
- hypertension
- disturbed calcium
- CVD
- Bone disease
- immune suppression
- bleeding tendency
- treatment complications
What does the failure of fluid homeostasis lead to?
- inability to concentrate urine
- > loss of diurnal rhythm of urine excretion
- > limited rate of water excretion
- inability to excrete water load
- > oedema
- > hypertension
What is the treatment for fluid overload?
- diuretics
- salt restriction
- fluid restriction
if doesnt work then dialysis and transplant
What do electrolytes such as sodium do and cause?
- major cause of hypertension and fluid overload; damage to vessels and blood flow
- sodium must be within normal range
What do electrolytes such as potassium do and cause?
- enormous functional reserve to excrete potassium
- severe hyperkalaemia when GFR <10ml/min
- due to:
- > excessive load
- > interference with potassium excretion; acidosis with volume contraction and diabetic nephropathy
What ECG changes are seen with hyperkalaemia?
- tall T waves
- long QRS interval
- long PR interval
- cardiac arrest
-> alterations in membrane excitability
what is the treatment to prevent hyperkalaemia and hypernatraemia?
- salt restriction
- K+restriction
- dialysis and transplants if all else fails; drugs that act as K+ binders
State the equation for the carbonic acid buffer system and how this system works
CO2 + H20 H2CO3 H+ + HCO3-
- increasing H+ due to failure to excrete acid leads to increase in HCO3- and so increase in CO2 and H20
the CO2 is removed by lungs to maintain pH
there is an accumulation of hydrogen acid
What are the effects of acidosis?
- increased respiratory drive; breathless
- chest pain
- confusion
- bone pain
- demineralisation of bone
What is the treatment for metabolic acidosis?
- sodium bicarbonate
What does Vitamin D, renin and erythropoietin control?
Vitamin D- calcium metabolism
Erythropoietin- haemoglobin production
Renin- control of blood production
what is hypertension? and what mechanisms occur?
- high BP
- accelerates decline of kidney function
- contributes to CV risk
mechanisms:
- sodium retention
- volume expansion
- RAS activation
- sympathetic nervous system activity
- endothelial dysfunction
What is the treatment for hypertension?
- salt restriction
- diuretics
- RAS blockade
- other antihypertensive med
What happens when excretory function reaches failure?
- accumulation of toxic waste products
- > creatinine rises only after significant renal damage
- > nitrogenous waste retention occurs
- > urate retention then occurs
- > phosphate retention then will occur
what is the treatment for uraemia?
- dialysis or transplantation
why is protein restriction not used as treatment for uraemia?
due to it causing malnutrition which weakens the individual further
what happens when drugs fail to be excreted?
- many drugs are usually excreted by the kidney but the metabolism of these drugs will be impaired by renal failure
- toxicity due to accumulation of the drug will lead to:
insulin-> hypoglycaemia
opiates-> narcosis
anitbiotics-> encephalopathy
sedatives-> respiratory arrest
digoxin-> cardiac arrythmias
explain the purpose of dialysis?
dialysis removes the waste products and excess body fluids from the individual when the kidneys are failing to excrete these substances
explain what is narcosis
it is when a patient is in a state of unconsciousness or arrested activity due to narcotics or chemicals in the body
how can you prevent drug toxicity?
you can modify the prescription according to the renal function
- adjust the dose when needed
- adjust the frequency when and if needed
What three diseases show the greatest risk of harm when a patient has all of them?
CKD, CVD, diabetes
Why does CKD progress?
- major modifiable risk factors
- > uncontrolled underlying disease
- > hypertension
- > proteinuria
- > smoking
What is the treatment for the CKD?
- control underlying diseases
- treat hypertension
- ACEi/ARB
- stop smoking
what is acute kidney injury?
a rapid decline in kidney function and kidneys stop working properly
how can AKI be detemined?
Stage 1- >26umol/L increase
Stage 2- 100-200% increase
Stage 3- >200% increase or >354umol/L or needs dialysis
urine output
S1- <0.5ml/kg/hour for 6 hours
S2- <0.5ml/kg/hour for 12 hours
S3- <0.3ml/kg/hour for 24 hours or anuria for 12 hour or needs dialysis
Who is at risk of AKI?
- older age
- diabetes mellitus people
- people with hypertension
- heart disease
- liver disease
- CKD
what medication Is needed for AKI?
- ACEi/ARB
- Gentamicin
- Vancomycin
- Chemotherapy
Name the causes of AKI?
- pre-renal; perfusion failure
- renal; intrinsic disease of the kidney
- post-renal; obstruction of the urinary system
What is the purpose of renal auto regulation?
maintain constant eGFR/BP across diff blood pressure
What worsens perfusion failure?
- RAS blockade
- NSAID
- diuretics
- antihypertensives
how does BV and BP affect perfusion failure?
high BP+ high BV leads to high Renal perfusion and so normal urine production
normal levels of BP and BV lead to normal levels of renal perfusion and urine production which maintains perfusion
low BP and low BV leads to normal renal perfusion and urine production
low BP and low BV lead to low renal perfusion and low urine production; this is AKI