Kidney disease and renal failure Flashcards
What are the homeostatic functions of the kidney?
elimination of waste Water homeostasis Electrolyte homeostasis acid base homeostasis Blood pressure control
What are the metabolic/endocrine functions of the kidney?
Synthesis of hormones - Vitamin D, Erythropoietin, Renin
Excretion of drugs and drug metabolites.
What diseases can cause the kidneys to stop working?
Chronic kidney disease (CKD)
Acute Kidney Injury (AKI)
What are common causes of CKD?
Diabetes and or hypertension but also many other causes.
Usually slow and progressive onset and is often irreversible.
What are the common causes of AKI?
Rapid onset usually due to a combination of systemic illness and multiple risk factors and medication.
Usually reversible with treatment.
What is likely to develop AKI?
Elderly Diabetics Hypertension patients Heart disease patients Liver disease Patients CKD patients
Who is likely to develop CKD?
Diabetics
hypertension
Drug users especially NSAIDs
Elderly
What are the risk factors for CKD?
Increased age Hypertension Diabetes Smoking Poor education
What are some consequences due to a loss of renal function?
High mortality rate
Problems with electrolyte and water homeostasis
Acid base homeostasis issues
Endocrine irregular functionality.
what is the average cardiac output?
5L/min
What is the average renal blood flow?
1.2L/min
What is the average glomerular filtration rate?
125L/min (180-185 L/day)
What is the average urine volume?
1mL/min
1.5L/day
What controls water and electrolyte homeostasis?
ADH and renin-angiotensin system
What happens if salt and water homeostasis fails?
Inability to concentrate urine
Inability to excrete water load (oedema)
Sodium retention - hypertension, CNS dysfunction
What happens if potassium homeostasis fails?
Enormous functional reserve to excrete potassium
Severe Hyperkalaemia (when GFR <10ml/min)
Alterations in membrane excitability
Cardiac arrythmias
What causes to problems with acid base dysregulation?
Failure to excrete acid
Increase in H+
Increase in CO2 produced
Removed by lungs to maintain pH
What happens if acid base homeostasis fails?
Systemic acidosis
Symptoms of breathlessness (dyspnoea)
Physiological systems start to fail (enzyme function requires correct pH)
Cardiac muscle concentration is reduced
Acidosis drives Hyperkalaemia
What happens if vitamin D is not activated?
Hypocalcaemia
Muscle Spasms
Cardiac Rhythm problems
Hyperparathyroidism
What is hyperparathyroidism?
Bone fragility
Soft tissue calcifcation
What is caused if erythropoietin is not made?
Anaemia
What are the consequences of anaemia?
Impaired quality of life
reduced exercise capacity
impaired cognition
Transfusion requirement
Iron overload
Blood-borne infection
↑ risk of Left Ventricular Hypertrophy
↑ CV disease in patients with CKD
What happens if metabolic waste products are not excreted?
Accumulation of toxic waste products.
Can lead to confusion and heart problems
May cause Gout
May cause cardiovascular disease
Why are the metabolic waste products that would lead to heart problems, gout and confusion when accumulated?
Creatine rises after significant renal damage
Retention of nitrogenous waste
Retention of urate
Retention of phosphate
What is the role of the kidneys in drug metabolism?
Many drugs excreted by the kidney Metabolism of drugs may be impaired by renal failure
Increased risk of toxicity due to accumulation of drug
What are some complications caused by the loss of kidney function?
Anaemia Hypertension Disturbed calcium/phosphate homeostasis Cardiovascular disease
Bone disease Abnormal handling of drugs
Immune suppression Bleeding tendency
Complications of treatment
Why would you give a patient renal replacement therapy?
If they have acute or chronic kidney disease
If they are unable to maintain homeostasis functions of the kidney.
Without treatment these are terminal illnessses
What are some renal replacement therapies?
Dialysis
Conservative (palliative) care
Transplantation replaces all kidney functions
What is dialysis?
Extracorporeal therapy where fluid and solutes are removed or added to the patients blood.
How does dialysis work?
Works by separating the patients blood and the dialysis fluid with a semipermeable membrane
What is dialysis used to replace?
Used to replace the kidneys function of water, electrolyte, acid/base homeostasis and excrete metabolic waste products.
What are the types of dialysis?
Haemodialysis
Peritoneal
Where is peritoneal dialysis done?
At home
needs a permanent peritoneal catheter
Can be either continuous or overnight dialysis
How long does peritoneal dialysis last for?
8-10 years
What are the risk factors of peritoneal dialysis?
Risk of getting peritonitis
How does peritoneal dialysis work?
Dialysate is injected into the abdomen through a catheter.
This draws out the metabolic waste, electrolytes and excess fluid from the blood
This fluid is then drained out of the abdomen into a collection bag back through the catheter.
How does Haemodialysis work?
Preparation of an AV fistula or AV graft to connect a vein and artery together.
Need is placed into the vein and the blood flows out and into a dialysing machine which filters and cleans the blood.
The clean blood is then returned to the body through a needle into the artery.
What does haemodialysis require?
Needs permanent access to the circulation via an AV fistula, AV graft or central venous catheter.
How long does haemodialysis last for?
Must be done for 4 hours 3 times per week and can last indefinitely
What immunosuppressants are used for a kidney transplantation?
Steroids
Calcineurin inhibitors
Azathioprine
Mycophenolate
What are the benefits of a kidney transplant?
Better life expectancy
Better quality of life (no dialysis)
Replaces all renal functions
First choice treatment for CKD 5 (end stage kidney failure)
Who should have a kidney transplant?
Everyone with CKD 5 unless they have an absolute contraindication
What are absolute contraindications?
High peri-operative mortality
Poor life expectancy
Active malignancy
Where do the donor kidneys for a transplant come from?
Cadaveric donor
Living donor
Explain the problem of transplant immunology
Organ transferred between non-genetically identical individuals
Rejection of the graft
Driven by an allogenic response
Mechanisms that discriminate self from non-self
How can transplant immunological problems be prevented?
ABO blood group matching
HLA-A,B,DR matching
Screening for anti donor antibodies in the recipient.
