Pre Renal Disease Flashcards
What is the definition of pre-renal disease?
- hypoperfusion of the kidneys
- lack of blood to the kidneys
Rre-renal disease is recognised as hypoperfusion of the kidneys, and is normally caused by an acute presentation of an illness that is reversible. When looking at a urine dipstick what would we likley see?
- bland urine
What is renal disease?
- disease that directly affect the kidneys
Renal diseases are those that directly affect the kidneys. What are some common causes of renal disease?
- autoimmune disease
- acquired or inherited renal diseases (diabetes)
- nephrotoxic drugs
- diseases of intrinsic renal blood vessels
Renal diseases are those that directly affect the kidneys and could be causes by autoimmune disease, acquired or inherited renal diseases, nephrotoxic drugs, or diseases of intrinsic renal blood vessels. These can be acute but generally cause chronic kidney disease. When looking at a urine dipstick what would we likley see?
- prescence of blood and protein
Post-renal disease is anything that affects the kidneys, that occurs after the kidneys. What conditions can cause post-renal disease?
- bilateral ureteric stones
- prostate hypertropthy
- ureteric strictures
- urethral values
Post-renal disease is anything that affects the kidneys, that occurs after the kidneys. Conditions such as bilateral ureteric stones, prostate hypertropthy, ureteric strictures and urethral values can all cause post renal disease. How can patients urine present?
- positive for blood
- with no known systemic illness
When looking at acute kidney injury, place these in order of the % that they can occur:
- pre-renal disease
- renal disease
- post-renal disease
1 - pre-renal disease (most common)
2 - renal disease
3 - post-renal disease
Pre-renal disease is the most common cause of acute kidney injury and is generally cause by a physiological cause that causes a reduction in GFR, but is reversible. If this doesnt get reversed what can happen?
- can cause injury and become pathological, BUT generally reversible, but takes a long time
- if not reversed it can lead to chronic kidney injury and renal disease
If a patient has pre-renal disease which is due to hypoperfusion, what can this lead to, specifically in the tubules?
- ischaemia and tubular necrosis
- this then becomes renal disease
In the histology image below we can see necrotic tubules. Identify labels A, B and C?
- A = bowmans capsule
- B = glomerulus
- C = tubules with little or no epithelial cells (columnar or sqaumous) as they sloth off
What are 4 precipitatiing (make worse) conditions that may cause pre-renal disease?
- old age
- preexisting CKD
- concomitant drugs
- low mean arterial pressure (< 80mmHg)
Old age, preexisting CKD, concomitant drugs and low mean arterial pressure (< 80mmHg) can all precipitate (make worse) pre-renal disease. What are the kidneys compensating mechanisms to account for the precipitating factors?
1 - release of renin trigger Angiotensin 2 release
2 - norepinephrine released by adrenal gland that raises systmeic BP
3- renin causes release of antidiuretic hormone, which retain H2O, increasing blood volume and blood pressure
Intravascular volume depletion can cause hypoperfusion, what does that mean?
- loss of blood in circulating system
- haemorrhage, diarrhoea, internal bleeding etc..
Decreased cardiac output can cause hypoperfusion, what does that mean?
- reduction in blood being pumped out of heart
- disease of heart
- pulmonary hypertension/embolism
- systemic vasodilation
- drugs
Renal vasoconstriction can cause pre-renal disease, what are a few examples of causes of this?
- norepinephrine
- liver disease
- sepsis
- hypercalcemia
Renovascular diseases can cause pre-renal disease, what are a few examples of causes of this?
- atherosclerosis (hardening, narrowing of vessels)
- thromboembolic disease (blockage of arteries)
- renal artery dissection (tearing of renal arteries)
Some drugs can cause pre-renal disease, what are a few examples of these?
- angiotension-converting enzyme inhibitors (anti-hypertensive)
- inhibition of prostaglandin synthesis by Nonsteroidal anti-inflammatory drugs during renal hypoperfusion (pain killers)
In the image below, the left image is healthy renal blood flow, but what do the arrows denote in the image on the right?
- artherosclerosis causing renal stenosis
In response to a reduction in blood flow to the glomerulus the kidneys release renin, causing activation of RAAS. Angiotensin II is able to cause constriction of efferent capillaires in the glomerulus and this increase pressure in afferent capillaries and inside the glomerules, allowing GFR back to normal levels. However, when patients taken angiotensin II inhibitors (ACE), something is stopped, what is this?
- efferent arterioles vasodilate
- glomerules pressure drops as does GFR
- hypoperfusion and acute kidney injury occurs
In a patient with acute kidney injury what drug should be discontinued and why?
- angiotensin II inhibitors (ACE) such as Ramipril
- increases hypoperfusion, reducing GFR and increasing kidney injury
In acute kidney injury the use of ACE inhibitors (Ramipril) is not advised as it reduces glomerular pressure and GFR. However, why is reducing glomerular pressure a good thing?
- chronic high pressure causes capillaries to dilate and become thickened
- capillaries become less responsive and increase risk of kidney injury
- GFR will therefore be reduced
What cells line the tubules of the kidneys?
- sqauous/cuboidal/columnar epithelial cells
- depends where in tubules
In acute tubular necrosis what happens to the epithelial cells that line the tubules?
- they are shedded off
- leaves hollow and disperced tubules
- no inflammation though
What antibiotic can cause acute tubular necrosis?
- vancomyosin
What anti-inflammatory/painkillers can cause acute tubular necrosis?
- NSAIDs including COX inhibitors
What anti-hypertensives can cause acute tubular necrosis?
- ACE inhibitors
- Ramipril
In pre-renal injury, which is the most common cause of acute renal injury, what are the 3 sites that can be damaged?
1 - tubules
2 - glomerula
3 - vascular (blood vessels inside the kidneys)
Any pre-renal injury that is left untreated can cause what?
- acute tubular necrosis
- this can then become toxic or ischemic
What are the progressions of acute kidney inury following hypoperfusion?
- acute kidney injury (most common cause)
- renal kidney injury/failure follows, defined as oliguria
- can develop chronic kidney disease (>3months)
When defining acute kidney injury, what is the diagnosis based on creatinine?
- increase in serum creatinine by 26.5 umol/l within 48 hours
- increase in serum creatinine to x 1.5 times baseline, which is known or presumed to have occurred within the prior 7 days;
When defining acute kidney injury, what is the diagnosis based on urine output?
- <0.5 ml/kg/h for 6 hours
What determines stage 3 of acute renal injury?
- 3 x normal serum creatinine
- initiation of dialysis
In patientds with acute kidney injury there are some generic treatments are are used for stage 1, 2 and 3, what are they?
- stop all nephrotoxic drugs
- avoid hypoglycaemia
- ensure volume and haemodynamics status
- monitor creatinine and urine
- avoid radiocontrast investigations and see alternatives
In patientds with acute kidney injury there are some generic treatments are are used for stage 1, 2 and 3, what are they. However, for stage 2 and 3, what should be done for patients?
- look at changing drug dosages
- consider administration to ICU
In patientds with acute kidney injury there are some generic treatments are are used for stage 1, 2 and 3, what are they. However, for 3 specifically, what should be done for patients?
- consider renal replacement therapy
In a patient with an acute kidney injury what haematological aspects should be checked to help diagnose the patient?
- full blood count (WBC)
- urea and electrolytes (filtration/re-absorbtion)
- C-Reactive protein (acute inflammation)
- multiple myeloma screen (pre-cursor for lymphocytes of bone cancer)
In a patient with an acute kidney injury what cultures shoukd be done to help diagnose the patient?
- blood and urine cultures
- antibiotic sensitivity
In a patient with an acute kidney injury what can be tested on urine?
- urine culture with antibiotic sensitvity
- serum dipstick
- serum microscopy
What liver viruses can cause acute kidney injury?
- hepatitis B, C and HIV
In a patient with an acute kidney injury what imaging test should be performed on the Kidney Urinary and Bladder?
- ultrasound
- X-ray
- CT (non contrast)
In a patient with an acute kidney injury what what invasive test can be perfomed to assess the risk of intrinsic renal disease?
- renal biopsy
In a patient with acute renal injury, what would we expect to see in the serum urea, creatinine and K+ levels?
- all elevated
- hyperkalaemia can be dangerous and cause cardiac arrhythmias
In a patient with acute renal injury, what would we expect to see from an arterial blood gas in the following parameters:
- pH (7.35-7.45)
- pCO2 (4.6-6.4 kPa)
- pO2 (11-15 kPa)
- HCO3- (23-30 mmol/L)
- pH (7.35-7.45) = ⬇️
- pCO2 (4.6-6.4 kPa) = ⬇️ due to increased respiration rate
- pO2 (11-15 kPa) = normal
- serum HCO3- (23-30 mmol/L) = ⬇️
- causes metabolic acidosis
In patients with acute kidney injury, what are the first line treatments?
- appropriaye fluid balance
- BP MAP >80mmHg
- administer antibiotics if risk of sepsis
In patients with stage 3 acute kidney injury, what treatment should be considered?
- renal replacement therapy dialysis (renal ward) or haemofiltration (ICU)
In patients with stage 3 acute kidney injury, renal replacement therapy dialysis (renal ward) or haemofiltration (ICU) should be considered. What are the indications for this?
- fluid overload
- hyperkalaemia
- worsening metabolic acidosis
- ureamia (waste products build up in the urine)
What is the definition of chronic kidney disease?
- abnormal renal function that persists for > 3 months
Abnormal renal function that persists for > 3 months is the definition of chronic kidney disease. There are 5 stages of chronic kidney disease, at what stage should a patient be placed on dialysis?
- stage 5
- 15ml/min/1.72m3
What is the most common cause of chronic kidney disease?
- diabetes (type 1 or 2)
