Renal

Question 1

GFR

Answer 1

The volume of filtrate produced by the glomeruli of both kidneys each minute.
Beth derived by a 24hr sample of urine (nor practical ; eGFR used in practice)

Question 2

EGFR

Answer 2

Reported under U&E blood results
Calculated via equations
Normalised to a standard body surface area of 1.73m2
Lab results do not state specific eGFR> 60ml/min
May over/under estimated Renal function in patients of extreme body weight (may lead to over / under dosing of meds )
Also can be unreliable in certain ethnic Groups

It therefore should not be used in calculating drug doses when :
Patients are of extreme weights
Drug has a narrow therapeutic window

Question 3

Creatinine

Answer 3

Breakdown product of muscle and completely removed by glomerular filtration.
Increased cr = increased renal impairment

A reduced muscle mass may have a falsely low reading of cr and therefore over estimation of cr and vice versa

Question 4

CrCl

Answer 4

Crcl (ml/min) = (140-age) x weight (kg) x constant / serum cr (micromol/L)

Constant = 1.23 (M) 1.04 (F)

More accurate than eGFR for calculating drug doses as it also considers the patients weight.

Question 5

EGFR V CRCL.

Answer 5

Compare to both to see if they are the same or different
CRCL RECOMMENDED-
drugs with narrow therapeutic windows
Patients at extremes of body weight
Elderly patients
Chemotherapy
If manufacture advices ie DOACS

LIMITATIONS TO CRCL
cr levels need to be stable
Inaccuracies at extremes of body weight - need to use ideal / adjusted body weight

Question 6

AKI

Answer 6

Sudden reduction in kidney function.
Common and serious problem

Question 7

AKI DIAGNOSIS

Answer 7

Rise in serum cr of 26 micromol/L or more within 48hrs
50% or greater rise in serum creatinine known or presumed to have happened in the last seven days
Fall in urine output to less than 0.5ml/kg/hr for more than 6 hours in adults and more than 8 hours in children and young people
25% or greater fall in eGFR in children or young people in the last 7 days

Question 8

AKI causes

Answer 8

Pre renal - reduced blood flow to the kidneys
Renal - structural damage to the kidneys
Post- renal - obstruction to outflow from kidneys

Question 9

How can NSAIDS cause drug induced Pre renal AKI

Answer 9

NSAIDS inhibit synthesis of prostaglandins which causes dilation of the afferent arteriole and as a result the afferent arterioles narrow , this lowers the pressure in the glomerular caPillaries leading to a reduced filtration rate

Question 10

How do ACE inhibitorsn and ARBs cause drug induced pre renal AKI

Answer 10

After filtration blood exsits through the efferent arteriole . ACE inhibitors and ARBs cause widening of the efferent arteriole which slows the flow of blood and reduced the glomerular filtration rate

Question 11

What affects do diuretics have on kidney

Answer 11

Diuretics can cause increased or excessive preoduction of urine exacerbating hypo plasmin and reducing renal flow.

Question 12

AKI signs and symptoms

Answer 12

EXCRETION OF FLUID DECREASED
reduced urine output
Peripheral / pulmonary oedema

REDUCED K EXCRETION
HYperkalemia

REDUCED ACID EXCRETION
metabolic acidosis