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