W11 Acute and Chonic Kidney Disease Flashcards
what is glomerular filtration rate
rate at which the glomerulus is filtering the blood to form the filtrate
what is the GFR for males
90 - 140 ml/min
what is the GFR for females
80-125ml/min
what criteria does the substance used to measure GFR need to fufill
completely filtered
not re-absorbed
not secreted
not metabolised by the nephron
why is inulin not used even though it meets all the criteria
it is not practical as it requires an infusion into the blood
what substance do we use
creatinine clearance is measured
what is creatinine
it is a chemical waste molecule that is generated from muscle metabolism
what is creatinine produced from
creatine which is a molecule of major importance for energy production in muscles
how is creatinine excreted
removed from the circulation by filtration and excrted in urine
What does a rising creatinine level indicate
kidneys not functioning to their full ability
what potential problem can lack of kidney function cause
loss of nutrients from the body
failure to remove toxins
affect drug treatments
affect blood pressure
what is creatinine concentration used for
determine sufficiency of kidney function
determine severity of kidney damage
monitor progression of kidney disease
what is creatinine clearance
it is a value which indicates the volume of creatinine in ml removed by the kidneys over a period of time per minute
how do we take creatinine clearance
blood is taken from the patient
this is measuring the amount of creatinine in the blood plasma
the higher the level of creatinine in the blood the slower the kidneys are working
which equation do we use to calculate the creatinine clearance
there are many but the most common is the cockcroft and gault equation
what is the cockcroft and gault equation
it states firstly that factor known as F which is a constant
male = 1.23 female = 1.04
F x (140-age) x weight / serum clearnace
units = ml/min
what is eGFR
estimated glomerular filtration rate
how is egfr different from gfr
the labs calculate egfr using a different equation and its units are
ml/min/1.73m^2
what is eGFR used for
can be used to guide dosage for most drugs in patients of an average build
in what patients must creatitine clearance be measured
DOACs
Nephrotoxic
> 75 years
Extreme of muscle mass
Drugs that are renally excreted
Narrow therapeutic index drugs
what does DOACs stand for
direct-acting oral anticoagulants
what can serum creatinine be affected by
The amount of muscle tissue you have
High protein in diet
Exercise particularly in muscle building
Any injuries involving damage to the muscle
Malnutrition leading to dramatic weight loss
What does AKI stand for
Acute Kidney Injury
what does AKI replace
acute renal failure
define acute
develops over hours or days
how common are AKI’s
1 in 5 patients in A&E
13-18% of all hospital admission
where is AKI common in
patients who are at risk or who are acutely ill or who have had a major surgery
What are the risk factors for AKI
Age > 75 Previous AKI PRe existing CKD (eGFR <60ml/kg/1.73m^2) Heart failure Atherosclerotic peripheral vascular disease (PVD) Deabetes mellitus Liver Disease Debility and Dementia
What are triggers for AKI
Sepsis or Infection Hypotension Hypovolaemia (dehydration, bleeding) Nephrotoxic medications e.g. gentamicin, NSAIDS, iodinated contrast Anti-Hypertensives
What are the 3 classifications of AKI
Pre renal
Renal
Post Renal
what is a pre renal aki
inadequate perfusion, not enough blood at sufficient pressure to allow filtering
what is a renal aki
cellular damage, damage to the cells that make filtering mechanism possible
what is a post renal aki
obstruction, urine unable to drain adequately system backed up
what are the main causes of a pre renal aki
intravascular volume depletion
- haemorrahge
- vomiting
- diarrhoea
decreased arterial pressure
- heart failure
- sepsis
nephrotoxic medication
- ACEIs
- ARBs
- NSAIDs
what are the main causes of post renal aki
kidney stones
benign prostatic hyperplasia
CNS disorders that may affect outflow such as stroke
how do we manage a pre renal AKI
hydration with IV fluids
how do we manage a post renal AKI
refer patient to a urologist
how do we manage an intrinsic AKI
treat the damage if possible
what is a general rule of thumb for AKI management
hold all nephrotoxic medications
adjust doses of all other medications that are prescribed
what can further complications include
Hyperkalaemia
Metabolic acidosis
Fluid overload
Uraemic encephalopathy (high levels urea in the blood)
How do we manage hyperkaelemia in people who have an AKI
restrict dietary potassium
treat insulin or salbutamol causing a shift of potassium from the blood stream into cells
Potassium persistently high, patietns may need to undergo urgent dialysis
How do we manage acidosis
solution to neutralize the pH of the blood often IV sodium bicarbonate is given and often these patients are admitted to HDU / ITU
how do we manage oedema in people who have an AKI
give a loop diuretic e.g. furosemide whic his often given IV at a high dose
monitor serum creatine as there is a risk of worsening pre renal aki through dehydration
not all patients will be responsive so if persistently fluid overloaded patient may need to go through dialysis
how do we manage uraemic encephalopathy
undergo urgent renal replacement therapy (dialysis to remove the toxic urea from the blood
what complications require dialysis
hyperkalaemia
oedema
uraemic encephalopathy
what does nephrotoxic mean
Nephrotoxicity is one of the most common kidney problems and occurs when your body is exposed to a drug or toxin that causes damage to your kidneys. When kidney damage occurs, you are unable to rid your body of excess urine, and wastes.
give some examples of nephrotoxic potential medicines
ACEIs ARBs NSAIDs Diuretics Aminogylcosides Iodinated contrast agents
what is chronic kidney disease
abnormalities of kidney function or structure present for more than 3 months with implications for health
what prompts can lead to taking the GFR
persistant microalbuminuria
persistent proteinuria
pesrsistant haematuria
