Case 3- acute kidney disease and chronic kidney disease Flashcards
Acute kidney disease (AKI)
A sudden episode of kidney injury that happens over a few hours or days. It causes a build up of waste products in your blood and makes fluid balance harder, Can affect other organs like the brain, heart and lungs. It is treatable
Creatine levels and urinary output in AKI
In a blood test where there is an increase in creatine levels 1.5 times the baseline or more than 26.5 micro mol/L within 48 hours. Also reduced urine output at less than 0.5ml/kg/hr for over 6 hours. AKI can lead to CKD, or even acute onset chronic kidney disease.
AKI risk factors
Over 65, history of AKI and CKD, heart failure, liver disease and diabetes. Neurological or cognitive impairment, sepsis, Hypovolemia, oliguria (little urine output) and nephrotoxic drug use within the last week like ace inhibitors. When you are immunocompromised, or can be the result of toxins, cancer and cancer therapy.
3 causes of AKI
Pre-renal, renal and post renal
Pre-renal causes of AKI
Reduction of perfusion to kidneys leading to injury before the kidney. Can be due to cardiac failure or acute coronary syndrome. You can be hypovolaemic for a number of reasons such as diarrhoea or dehydration. Volume can be lost into other tissues such as cirrhosis and nephrotic syndrome. You may have a blocked renal artery such as thrombosis or stenosis but will only affect one kidney. Can be caused by drugs such as ibuprofen or ace-inhibitors (NAIDS). Can also be due to 3rd space loss which is the abnormal accumulation of fluid into an extracellular and extravascular space
Renal causes of AKI
Damage to the kidney last thing to look at. Can be Glomerulonephritis .Could be acute tubular necrosis causing odemia, Hypertension and Haematuria. Vasculitis can occur in the kidney blood vessels which are inflammation based. Can be acute tubular necrosis due to either toxic substances or ischaemia. Can be acute interstitial nephritis
Glomerulonephritis
Inflammation of the Glomerulus, this leads to damage which allows blood and protein to leak into the urine. You have different types: segmental gomerulosclerosis, membranous nephropathy and IgA nephropathy. Can present with isolated haematuria, proteinuria, nephritic and nephrotic syndrome, acute renal failure and chronic renal failure
Post renal causes of AKI
Blockage of urinary track causes a build-up of waste in the kidneys, will eventually cause damage and hydronephrosis. Can be unilateral or bilateral damage. Obstruction at any level such as tumour or stone. This will cause Hydronephrosis where the kidney swells. Blockage of the urethra will cause bilateral Hydronephrosis and will affect both kidneys.
Other causes of AKI
1) Rhabdomyolysis- damage of skeletal muscle release myoglobin into the circulation, it is toxic in the tubule
2) Crush injuries- due to a long-lie from overdose or age, presents with brown “coca-cola” urine
3) Haemolytic uraemic syndrome
Most likely cause of AKI
You first investigate pre-renal causes then post-renal and finally renal causes. Though renal causes are uncommon
Initial investigation in a pre-renal AKI cause
1) Urinary and electrolytes (U+E’s) to confirm AKI.
2) Dipstick analysis/urinary microscopy to detect micro-cultures.
3) Liver function tests and bone profile
4) Full blood count and C-reactive protein test (CRP)
5) ECG and chest X-ray
Investigations for a post renal cause
Ultrasound kidney ureter bladder (KUB) to look for evidence of obstruction like a stone or Hydronephrosis
Investigations for a renal cause
Done after post-renal and pre-renal. Immunology test and vasculitis screen. Renal biopsy may be performed
When is dialyses used?
Criteria is AEIOU Acidosis (7.1pH) Electrolytes (hypercalaemia) Intoxicants (get rid of drugs) Overload (too much fluid) Uraemia (remove urine)
Treatment for post-renal and pre-renal causes
Pre-renal treatment is about blood flow to the kidney and treating the cause, IV fluid is common. Post renal treatment is about removing the obstruction such as a urinary catheter.
The cardinal symptoms of renal disease
- No/minimal symptoms of kidney disease when it’s at an early stage.
- Later symptoms include weight loss and poor appetite
- Swollen ankles, feet or hands
- Shortness of breath
- Tiredness
- Haematuria
- Increased urinary frequency
- Difficulty sleeping (insomnia)
- Pruritis (itching)
- Muscle cramps
- Nausea and poor appetite
- Headaches
- Erectile dysfunction
Chronic kidney disease (CKD)
An abnormality of kidney structure or function, present for more then three months and has an effect on health
Normal GFR
100ml/min/1.72m
How to measure GFR
Hard to measure GFR, would need a substance that is not secreted or reabsorbed. Inulin is used to measure this as it is expensive, creatinine is used to estimate the GFR to give an eGFR. Less accurate at the normal levels of GFR, also affected by muscle mass as creatine is a by-product of muscle metabolism
Causes of CKD
Hypertension, diabetes, Glomerulopathies, urinary tract pathologies and congenital condition
Hypertensive nephropathy
Cause of CKD. Intimal thickening in pre-renal vessels cause narrowing of the lumen. Decreased blood flow to the nephron causes release of renin which activates RAAS causing further hypertension. Get a gradual ischaemic injury to the Glomerulus. Immune cells secrete growth factors (TGF-beta1) which cause mesangioblasts to secrete an extracellular matrix. Excess structural matrix leads to glomerulosclerosis.
Diabetic nephropathy
Causes CKD. Increased pressure in the nephron due to hypertension and arteriole vasoconstriction. Excess sugar due to diabetes stimulates RAAS which causes the vasoconstriction, non-enzymatic glycation is also a cause. This will result in hyperfiltration causing trauma and damage to the nephron. Such as mesangial expansion, podocytopathy, GBM thickening, Glomerulosclerosis. Can cause ischaemia as high pressure in glomerulus damages capillaries, vasoconstriction reduces blood flow to the rest of the nephron.
Glomerulopathies
Cause CKD. Disorders of the Glomerulus, may be due to nephritic and nephrotic syndrome. Thinning of the Glomerulus may result
Functions of the kidney
A WET BED Acid-base balance Water balance Electrolyte balance Toxin removal Blood pressure regulation Erythropoiesis Vitamin D activation
How does CKD affect acid base balance
In CKD blood becomes more acidic due to the inability to eliminate H+. Treat with sodium bicarbonate.
How does CKD affect water balance
CKD means unable to eliminate water from the body leading to hypervolaemia. Treat with diuretics and restrict fluid.
How does CKD affect electrolyte balance
In CKD there is less potassium excretion can cause cardiac arrhythmias, treated with low potassium diet
How does CKD affect toxin removal
Unable to remove urea in CKD to cause uraemia, cause nausea and loss of appetite. Sever effect is pericarditis.
How does CKD affect blood pressure regulation
In CKD the reduction in blood flow leads to renin secretion leading to hypertension which will worsen CKD.
How does CKD affect erythropoiesis
Erythropoietin is not produced, this makes red blood cells so can cause anaemia.
How does CKD affect vitamin D activation
The kidney is unable to activate vitamin D ion CKD, causes fall in calcium levels. The kidneys are a key organ in the regulation of bone metabolism through regulation of calcium, phosphate and vitamin D. People with CKD sometimes find their bones get weaker and thinner – osteoporosis and osteomalacia may result.
The classification of chronic kidney disease
Albumin levels- A1, A2, A3
GFR levels- G1, G2, G3q, G3b, G4, G5
Can also be classified by cause
Why do we have a multi-system approach in kidney management
The kidneys effect a lot of different systems. Can cause muscle weakness, problems in the eye and cardiac failure
Renal replacement therapy (RRT)
Is used when the symptoms are very bad. Can include kidney transplant, peritoneal dialysis, Haemodialysis. May be started when there are metabolic disturbances, fluid overload and symptom burden.
Haemodialysis
An AV fiscula may be created to increase venous blood flow. Treatment takes around 4 hours and occur multiple times week. Done at hospital. Blood is pumped through a dialyser exposing it to dialysis fluid through a semi-permeable membrane
Peritoneal dialysis
Dialyses is run into the peritoneal cavity and is then drained. Can be done at home. It’s repeated multiple times a day or over night. The dialysate is inserted into the peritoneal space and dialysis with waste product is drained from the peritoneal space. The waste products cross the semipermeable membranes into the peritoneal space.
Kidney transplant
They last 10-15 years, the donor can be living or dead. Immunosuppressive medication must be taken
