6. Renal system Flashcards
What is the renal system?
= responsible for the removal of wastes, as well as fluid and electrolyte balance
Two main causes of kidney disease
- diabetes and hypertension are the two main causes of chronic kidney disease
Function of the kidney
- filters blood (1.2L min)
- excretes unwanted waste products toxins and metabolic wastes)
- Regulates fluid and electrolyte balance
Biochemical changes (changes in electrolytes) that you would see with someone with acute renal failure and chronic renal failure
- Hyperkalaemia (kidney cannot excrete potassium) leads to abdominal cramping, muscle weakness, paralysis and cardiac arrest
o Caused by Excessive oral intake, renal failure, deficit of aldosterone, use of potassium sparing diuretic drugs, crush injuries or burns (K+ leaks out), prolonged or severe acidosis may displace potassium from cells - Hypernatremia (kidney cannot excrete excessive sodium) leads to high blood pressure, muscle twitching, weakness and disorientation
- Hypermagnesemia leads to a decrease in blood pressure, decreased heart rate, coma and cardiac arrest
- Hypercalcemia leads to muscle spasms, abnormal heart rhythm
What is chronic kidney disease (CKD)
= progressive loss of kidney function
- The destruction of renal mass with irreversible sclerosis and loss of nephrons leads to progressive decline in GFR
- GFR is clinically indicated by kidney damage or a decreased kidney glomerular
Progression of chronic kidney disease
5 stages
- Normal Kidney function (high GFR > 90ml)
- Mild kidney damage –> Kidney attempts to compensate for renal damage by hyperfiltration
- Moderate kidney damage Hyperfiltration through the nephrons, causes further loss of function
- Severe kidney damage - severe reduction of GFR (15-29 ml/min)
- End stage kidney disease - established kidney failure (<15ml/min)
What are the factors contributing to chronic kidney disease
= Long term hypertension and diabetes
- congestive heart failure
- lupus
- sickle cell anemia
- polycystic kidney disease
- analgesic neuropathy
What is anemia?
= A condition in which the blood doesn’t have enough healthy red blood cells. (deficiency of RBC)
Why might anemia occur as a result of chronic kidney disease?
- Iron deficiency Occurs as a result of CKD = body uses iron to make RBC – therefore the iron deficiency leads to anaemia
- When kidneys are diseased or damaged, they do not make enough EPO. As a result, the bone marrow makes fewer red blood cells, causing anaemia
What is Acute kidney injury?
- AKI is a sudden decline in kidney function and leads to disorders of acid/base, electrolyte and fluid balance.
- RIFLE staging system was required
R- risk I – injury F - failure L – loss E - end stage renal failure
What does pre-renal, intrarenal (intrinsic) and post renal mean?
Pre renal = problems with blood supply
intrarenal (intrinsic) = damage to kidney
Post renal = obstruction of urinary tract
Discuss the
pre-renal (problems with blood supply)
of Acute kidney injury
- Hypovolaemia (volume depletion) – haemorrhage, vomiting, renal fluid loss
- Low cardiac output – disease of myocardium, pulmonary
- Alterations in renal system vascular resistance ratio
- Renal hypoperfusion
- Hyper viscosity syndrome e.g. polycythaemia
Clinical signs thirst, tachycardia, orthostatic dizziness, reduced JVP, reduced axillary sweating, dry mucous membranes
discuss the
intrarenal (intrinsic)
of acute kidney injruy
- Diseases of the glomeruli or renal microvasculature e.g. SLE, glomerulonephritis
- Acute tubular necrosis e.g. ischaemia, toxins
- Intestinal nephritis e.g. NSAIDs, Lymphoma
Clinical signs fever, joint pain, flank pain, headache, dizziness, confusion, seizure, oliguria, oedema, hypertension, heart failure
discuss the
post renal
of acute kidney injury
Obstruction
- Calculi
- Cancer causing obstruction
- Prostatic hypertrophy
- Stricture of the urethra
Clinical signs suprapubic and flank pain, Colicky pain
What is chronic renal failure?
= progressive loss of kidney function
Pre renal of chronic renal failure?
sudden reduction in blood flow in kidney
- poor cardiac function
- chronic liver failure
- atherosclerosis of the renal arteries
Intrarenal of chronic renal failure?
changes within the kidneys
- diabetic nephropathy - most common cause of CFT, chronic glomerular, nepritis, vasculitis, polycystic kidney disease
Post-renal of chronic renal failure?
Obstructions can cause urinary backflow and put pressure on the kidneys.
- Examples include: kidney stones, bladder outlet obstruction, retroperitoneal fibrosis
what is an upper urinary obstruction?
= a blockage of the passage of urine (can occur at any site along the tract)
causes of an upper urinary obstruction?
- Narrowing of the ureter or urethra
- Compression due to either a congenital defect or physical compression from a blood vessel, scaring, tumour or abdominal inflammation
- Renal calculi (kidney stones)
- Malignancy in either the renal pelvis, ureter, prostate or bladder
Effect on the kidney function of urinary obstruction:
effect depends on size of obstruction
- Initially the urine backs up which leads to the dilation of the ureter, renal pelvis and calyces
- Within 14 days it will affect both the proximal and distal part of nephron
- Within 28 days the backflow of urine will lead to the glomeruli becoming damaged and consequently the renal cortex and medulla will decrease in size
- total obstruction = leads to damage of renal tubule in 4 hours and is irreversible if not corrected within 4 weeks
