Flashcards in Week 5 Deck (82):
What drugs vasoconstrict the afferent arteriole? What does this cause?
NSAIDs e.g. naproxen.
Causes decreased glomerular filtration rate.
What drugs vasodilator the afferent arteriole? What does this cause?
Increases glomerular filtration rate.
What drugs vasoconstrict the efferent arteriole? What does this cause?
Causes an increase in glomerular filtration.
What drugs vasodilator the efferent arteriole? What does this cause?
Causes a decrease in glomerular filtration rate.
What is renal osteodystrophy?
When the kidneys become damaged in chronic kidney disease- it means they hydrolysing vitamin D to its active form. This means that calcium isn't absorbed from the gut to replace that lost from the bone. This causes weak bones.
Acute kidney injury can be...
Pre, intra or post renal.
Causes of pre-renal AKI?
Due to hypoperfusion of the kidney e.g. from renal artery stenosis, hypovolaemia due to diarrhoea, sepsis causing hypovolaemia, hypotension due to cardiac causes e.g. MI.
What would happen if AKI wasn't treated?
It would mean the kidney would undergo acute tubular necrosis due to lack of oxygen.
How would you diagnose AKI?
Ultrasound is needed to check for obstruction and to check the size of the kidneys (to check for acute exacerbation of chronic kidney disease which will mean the kidneys are often smaller)
What would you do if the ultrasound reveals no apparent cause of hypoperfusion of the kidneys and they appear to be normal size?
Urgent renal biopsy
What is the treatment for hyperkalaemia?
Calcium gluconate 10% 10mls IV- cardioprotective against arrhythmias.
10 units of act rapid insulin and 50mls of glucose 50%IV- insulin causes potassium to move into cells and glucose prevents the subsequent hypoglycaemia it would cause.
2.5mg of salbutamol. Beta agonists cause pottasium uptake in cells.
Will the acute treatment of hyperkalaemia suffice?
Patient is most likely to need heamo-dialysis as the acute treatment is only temporary.
What are the stages of chronic kidney disease?
Stage 1- GFR normal- >90. Has to have evidence of kidney damage.
Stage 2- GFR 60-90. Need evidence of kidney damage.
Stage 3- GFR 30-59.
Stage 4- GFR of 15-30
Stage 5- GFR of less than 15 OR on renal replacement therapy.
Pathogenesis of diabetic nephropathy
High blood glucose causes release of vasoactive mediators that dilate the afferent arteriole increasing GFR. Also causes a release of growth factors causing renal hypertrophy and mesangial expansion.
This causes nodule formation and diffuse glomerulosclerosis.
This causes inflammation, proteinuria (due to GBM thickening and podocyte dysfunction) and tubulointerstitial fibrosis.
How would you diagnose diabetic nephropathy?
History of DM
Presence of other diabetic problems (if they have retinopathy they are likely to have issues with their kidney)
Renal impairment (late finding)
Describe the 3 stages of diabetic nephropathy
Stage 1: Pre
- renal hypertrophy
Stage 2: Incipient
Stage 3: Overt
-mesangial nodules (Kimmel-steil wilson lesions)
How would you prevent and manage diabetic nephropathy?
Prevention- good glycaemic control
Antihypertensive therapy- tight BP control (< 130/80) using ACE inhibitors and ARBs
How do you slow the progression of diabetic nephropathy?
What is ischaemic neuropathy?
Refers to the reduced GFR associated with reduced renal blood flow beyond the level of auto regulatory compensation.
Over time- can lead to renal atrophy and progressive CKD.
What can cause ischaemic neuropathy?
Secondary hypertension- due to atherosclerosis in the renal arteries causing stenosis
Or fibromuscular dysplagia
What occurs if the renal is under-perfused?
It activates a series of hormonal and neuronal responses resulting in an increase in systemic bp.
This is due to the increased blood pressure trying to overcome the blockage and perfuse the kidneys. It compensates a bit. When you then treat the high blood pressure- the kidneys become even more under-refused hence the AKI.
Who gets atherosclerotic renal vascular (renal artery stenosis) disease?
Older patients (greater than 50)
Males affected more than females
Clinical presentation of renal vascular disease?
AKI after treatment for hypertension
CDK with diffuse vascular disease
Flash pulmonary oedema
What investigation would you use to look into renal artery stenosis?
Renal artery US
Renal artery duplex studies
How would you treat renal artery stenosis?
Medical therapy- Statin
angiography +/- stenting.
When are ACE inhibitors as treatment for renal artery stenosis contraindicated?
When it is bilateral disease. In unilateral they protect the other kidney by lowering the bp and preventing further damage. However they also decrease GFR and if both kidneys are already affected by stenosis- the GFR will already be very low. Therefore ACE inhibitors will not be helpful.
What is fibromuscular dysplagia?
Non atherosclerotic, non-inflammatory disease of the blood vessels that results in abnormal growth in the vessel walls.
What can fibromuscular dysplagia be associated with?
Ehler danlos syndrome.
What other artery can fibromuscular dysplagia cause?
Other than the renal artery can involve the cerebral artery.
What is myeloma?
Cancer of plasma cells (B lymphocytes)
They normally produce antibodies.
What occurs in myeloma?
Multiple plasma cells accumulate in the bone marrow impairing production of normal blood cells.
They produce a paraprotein (abnormal antibody) that causes renal dysfunction.
Symptoms of myeloma?
Signs of myeloma?
Classical presentation of myeloma?
Back pain and renal failure.
Glomerular manifestations of myeloma?
Monoclonal immunoglobulin depositation.
Tubular manifestations of myeloma?
Light chain cast nephropathy
Miscellaneous renal manifestations of myeloma?
Dehydration, hypercalcaemia, contrast, bisphosphonates, NSAIDs.
How would you diagnose myeloma?
Need a high index of suspicion
Bloods- serum free light chains. Serum free electrophoresis.
Urine- presence of bence jones protein
Bone marrow and renal biopsy
Management of myeloma?
Stem cell transplant
What type of vasculitis normally affects the kidney?
How would patients present with small vessel vasculitis?
Fever, arthralgia, weight loss, malaise
What is ANCA associated small vessel vasculitis?
Necrotising polyangitis that affects capillaries, venules and arterioles.
Who gets ANCA associated small vessel vasculitis?
People tend to present in their 5,6 or 7th generation.
How would you diagnose small vessel vasculitis?
Bloods- look for raised inflammatory markers, AKI and anaemia.
Immunology- ANCA, Anti-MPO and Anti PR3
Presentation fo granulomatosis with polyangitis?
Predominantly anti PR3 antibodies
Inflammation most commonly affects the respiratory tract.
Presentation of microscopic polyangitis?
Predominantly anti MPO antibodies.
Small vessel vasculitis with no granulomas.
Presentation of eosinophilic granulomatosis?
Asthma and eosinophilia. Also sometimes skin involvement.
Management of small vessel vasculitis?
Immunosupression- steroids and cyclophosphamide.
What renal involvement do lupus patients get?
Most frequently observes abnormality if proteinuria.
A number of types of renal disease can occur and are differentiated by renal biopsy.
Describe the classification of lupus nephritis?
Class I- minimal mesangial
Class II- Mesangial proliferative
Class III- Focal proliferative
Class IV- Diffuse proliferative
Class VI-advanced sclerosing.
What is renal replacement therapy?
Either transplantation or dialysis
Two types of dialysis?
Haemodialysis and peritoneal dialysis
How does haemodialysis work?
The blood is filtered into a tube that runs alongside a semi-permeable membrane. On the other side of the tube is dialysis fluid containing water, small amounts of sodium, urea and potassium and large amounts of bicarbonate.
Due to the concentration difference- the large amounts of sodium, potassium and urea in the blood move across to the dialysis fluid creating an equilibrium. The bicarbonate moves the opposite way into the blood (to stop acidosis in the patient).
Water moves across by a negative pressure from the blood into the dialysis fluid.
How can you gain access to a patients blood?
Need to either put in a fistula or a tunnelled venous catheter.
What is a fistula?
A vein is attached directly into an artery. This makes a high pressure system and the vein starts to get bigger. This is a good place for blood to be taken as it is strong.
Pros and cons of fistulas?
Pro's- good blood flow
Cons- takes 6 weeks to prepare after surgery.
What is a tunnelled venous catheter?
A line straight into the jugular vein. Good for emergency situations e.g. AKI.
However higher risk of infection.
What is peritoneal dialysis?
Instead of using an artificial membrane- the peritoneum is used as a membrane. It can be done either over night automated peritoneal dialysis, or 4 times daily for half an hour (continuous peritoneal dialysis).
What is in the dialysis fluid in peritoneal dialysis?
High levels of glucose to attract water by osmosis.
Low levels of potassium, urea, and sodium to attract these to diffuse across.
What can go wrong with peritoneal dialysis?
Peritonitis- usually infection by staph aureus. If you cough- strep.
Thickening of the peritoneal membrane meaning water cannot diffuse across.
Hernias (increased intraabdominal pressure and interfere with dialysis)
Describe the restrictions a dialysis patient will have to endure?
Water restriction- no more than 1 litre per day
Phosphate restriction (have to take phosphate binding pills)
What metabolic complications can you get from end stage renal failure?
Leading to hypocalcaemia and release of parathyroid hormone
Low 1,25 vitamin D
Anaemia- low epo and iron deficient
Salt and water retention
When would you start a patient on dialysis?
or Urea >45
Or based on symptoms- fatigue, lethargy, nausea/vomiting, itch
Define acute kidney injury?
An abrupt reduction in kidney function defined as a serum creatinine of >26.4
Or an increase in creatinine by >50%
Or a reduction in urinary output.
KDIGO staging of AKI
Based on serum creatinine or urine output (in practice- creatinine)
Stage 1- >26 or 1.5-1.9 x reference creatinine
Stage 2- 2-2.9 x reference creatinine
Stage 3- > or = 3 x reference creatinine or >354 or need for RRT.
Stage 1- <0.5ml/kg/hour for >6 hours
Stage 2<0.5ml/kg/hour for >12 hours
Stage 3<0.3mk/kg/hour for >24 hours.
Risk factors for AKI
Chronic kidney disease
Peripheral vascular disease
How is AKI classified?
Pre-renal causes of AKI
All result in hypo perfusion of the kidney
- Hypovolaemia due to fluid/blood loss. Could be haemorrhage or D and V
-Hypoperfusion- ACEi/ARBs. NSAIDs
-Hypotension- cardiogenic shock, disruptive shock.
What does untreated pre-renal AKI lead too?
Acute tubular necrosis.
What can cause acute tubular necrosis?
Rhabdomyalysis- breakdown/injury of muscle
Sepsis and severe dehydration
Treatment of pre-renal AKI?
Assess for hydration- Cap Refill, BP, HR, UO, oedema
0.9% NaCl solution- give bolus of fluid and then reassess as necessary
If greater than 1000mls and no improvement- get help.
Causes of intrinsic renal AKI?
Disease causing inflammation or damage to the cells causing AKI
-blood vessels- vasculitis
-glomerular disease-glomerular nephritis
-tuberlar injury- acute tubular necrosis, drugs (gentamicin), rhabdomyolysis, contrast
-interstitial injury- drugs, infection, systemic
Signs and symptoms of Aki
Anorexia, fatigue, weight loss, lethargy
Nausea and vomiting
Fluid overload (oedema, SOB)
Signs- pleural and pulmonary effusions due to fluid overload
What would give you a clue that it is a renal cause?
Sore throat, rash, joint pains, D&V, haemoptysis
What initial investigations would you do into AKI?
U&E's- Potassium high?, creatinine?
FBC and coagulation screen- abnormal clotting, anaemia
Urinalysis- proteinuria, haematuria
USS- size of kidney? Obstruction?
Immunology- ANCA, Anti-GBM, ANA
When would you biopsy in AKI?
Urgent- suspected rapidly progressing GN
-Positive immunology and AKI
Semi urgent- unexplained AKI to gain a diagnosis
Rule out obstruction, volume depletion and AVN
Further treatment of AKI?
Establish good perfusion- fluid resus. If still not adequate perfusion then use inatropes/vasopressors.
Treat underlying cause- antibiotics it sepsis
Dialysis if remains anuric and uraemia.
Life threatening complications of AKI?
Ureamic pericardial effusion
What is post renal AKI?
Blockage or obstruction leading to back pressure on the kidney (hydronephrosis) and stopping of function.
Causes of post renal AKI?
Stones, cancers, strictures, extrinsic pressure.
Treatment of post renal AKI?