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renal function Flashcards

1
Q

what do the kidney do

A

regulate the extracellular fluid volume and electrolyte composition compensate for daily variation in water and electrolyte intake.
they from urine in which potentially waste products of metabolism are excreted
they are endocrine organs which produce a number of hormone
They are controlled by other hormones

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2
Q

what hormones do the kidneys produce

A

erythropoietin
active form of vitamin D (calcitriol)
renin

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3
Q

what hormones control the kidneys

A

anti-diuretic hormone (ADH)
parathyroid hormone

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4
Q

the kidneys are full of nephrons. What are nephron

A

functional unit in the kidney is the nephron

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5
Q

what are nephrons made up of

A

glomerulus
proximal convoluted tubule
loop of henle
distal convoluted tubule

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6
Q

where does the filtration process take place in the kidneys

A

in the cortex

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7
Q

what process occurs at the glomerulus of the nephron

A

filtration- proximal tubule collects a filtrate from the blood containing water and low molecular weight solutes

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8
Q

put in order the terms (secretion, excretion, filtration and reabsorption) in accordance to renal function

A

filtration, reabsorption, secretion, excretion

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9
Q

what does GFR stand for and what is it

A

Glomerular filtration rate is how much filtrate is produced in a given time

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10
Q

why does the GFR decline with age

A

loss of functional nephrons so therefore the GFR provides an index of number of functioning glomeruli and estimates a degree of renal impairment

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11
Q

the GFR is equal to the maximum rate that the plasma can be cleared of any substance into urine, how can the amount cleared be calculated?

A

measuring the urinary concentration
multiplying by vol. of urine
dividing by the plasma concentration of substance
clearance= UV/P = ml mil^-1

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12
Q

what is creatinine

A

waste product of metabolism in muscle tissue
it is secreted by the kidneys

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13
Q

what is creatinine clearance

A

the volume of plasma that is cleared of creatinine per unit time

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14
Q

what does a progressive rise in plasma creatinine indicate

A

decline in renal function

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15
Q

why is there a lower level of plasma creatinine in women and children

A

because they have lower muscle mass

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16
Q

where does urea come from

A

liver makes urea from amino groups removed from spare amnio acids

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17
Q

when does concentration of urea increase

A

at low urine flow rates e.g dehydration because when urine is flowing more freely through the tubules there is more time for reabsorption to occur

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18
Q

when can low levels of urea occur

A

anorexia, malabsorption, liver failure

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19
Q

when can high levels of urea occur (uraemia)

A

pre-renal, renal and post renal disease

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20
Q

why is proteunurea an abnormal finding

A

because the glomerular filter should retain protein in the blood stream.

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21
Q

how can proteinuria be detected

A

dipsticks- indicates that there is damage to the glomerular filter

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22
Q

what is microalbuminurea and how much dame does it suggest to the glomerular filter

A

when there is small amounts of albumin in the urine suggests slight damage to the glomerular filter

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23
Q

what does it mean if there is immunoglobulins in the urine

A

damage to glomerular filter is severe

24
Q

what is the condition called when there is a very large amount of protein in the urine

A

nephrotic syndrome

25
Q

what is the main loss in nephrotic syndrome and what does it lead to

A

albumin and it leads to hypoalbuminaemia

26
Q

why do the low levels of albumin in the blood stream lead to oedema

A

because there is a low plasma osmotic pressure and it leads to secondary hyperaldosteronism

27
Q

what can cause nephrotic syndrome

A

glomerulonephritis
systematic lupus erythemarosis (SLE)
diabetic nephropathy

28
Q

what is renal failure?

A

it is defined as the cessation of kidney function. It can be acute or chronic

29
Q

how long does it take for acute kidney injury (AKI) to form?

A

kidneys fail over a period of days and is rapid
it is also reversible

30
Q

How long does it take for chronic kidney disease (CKD) to form?

A

develops over months and years and results in end stage kidney disease (ESKD)
and is irreversible

31
Q

Why is chronic kidney disease (CKD) irreversible?

A

because there is a progressive loss of functioning nephrons

32
Q

what can acute kidney injury arise from?

A

variety of problems effecting the kidneys and/or their circulation

33
Q

what indicates acute kidney injury

A

rapid increase in serum urea and creatinine
urine output falls to less than 400ml/day (oliguria), or no urine at all (anuria)

34
Q

what are the three classifications of AKI

A

pre- renal, post-renal, renal

35
Q

what is pre-renal AKI

A

kidney is failing to receive the proper blood supply

36
Q

what is post renal AKI

A

when the urinary drainage is impaired because of an obstruction. urine outflow from the kidney is obstructed and there is back pressure in the renal pelvis and at the renal pyramids.
That pressure will stop the glomerular filtration from happening

37
Q

what causes the renal classification for AKI

A

there is damage to the kidney tissue by some process or some disease.

38
Q

what can cause pre-renal injury

A

it can be caused by a decrease in plasma volume due to blood loss, burns, prolonged vomiting/ diarrhoea
there can be diminished cardiac output or occlusion of renal artery

39
Q

what happens to the biochemistry in AKI

A

increased serum urea and creatinine however the urea rises a lot higher than the creatinine because the reduced flow of filtrate through the tubules gives a longer time for reabsorption processes to occur

serum urea can also be increased due to trauma and muscle break down.

metabolic acidosis arises due to the inability to secrete hydrogen ions through the kidney so the hydrogens ions and retained in the plasma and they acidic the blood

hyperkalaemia occurs where blood potassium concentrations rise due to reduced filtration

increased urine osmolality

40
Q

what can post renal AKI do

A

post renal factors can cause a reduction in renal function which is caused by poor drainage of urine so back pressure builds up in Bowmans capsules so filtration at glomeruli is decreased

this can be caused by- renal stones, cancer pf prostate or cervix

41
Q

what is acute tubular necrosis

A

if pre/post renal damage is not corrected then patients can develop renal damage where the tubules can be damaged and cells can die

42
Q

other than pre/post renal failure what else can cause acute tubular necrosis

A

acute blood loss, septic shock, renal diseases e.g. glomerulonephritis, nephrotoxins- toxic damage from drugs

43
Q

what is the biochemistry of acute tubular necrosis

A

in early stages there I a slight increase in serum urea and creatinine
then there is a rapid rise over a period of days

44
Q

what are the three phases that patients with AKI go through

A

Oliguric phase- glomerular impairment predominates

Diuretic phase- there is a higher unite output and GFR improves but tubular function remain impaired

Recovery phase- renal dysfunction resolves

45
Q

what can the body not do with CKD

A

Unable to reabsorb water normally- because the tubes lose the ability to reabsorb water and concentrate urine
This can lead to polyuria with fixed, low osmolality

GFR becomes low because tubules can not excrete sodium to balance dietary intake
This can lead to sodium and water retention and worsening hypertension and oedema.

There is a disturbance in potassium metabolism- hyperkalaemia is a feature of advanced kidney disease and poses a threat to like because of the effect it has on the heart.
The ability to secrete potassium declines as GFR declines.

46
Q

in CKD how is acid/base balance disturbed

A

can’t regenerate bicarbonate and can no longer excrete hydrogen ions in urine
the retention of hydrogen ions causes metabolic acidosis

47
Q

how is calcium and phosphorus disturbed in CKD

A

serum phosphate increases due to low GFR

Serum calcium increases- this is because the ability to make calcitriol (active form of vitamin d) decreases therefore calcium absorption from GI tract decreases and hypocalcaemia occurs.

48
Q

what happens when hypocalcaemia occurs

A

the parathyroid gland is stimulated to restore the low levels of calcium but that can lead to secondary hyperparathyroidism as the parathyroid gland is working hard to restore the calcium to normal.

49
Q

how can tubular dysfunction happen

A

rarely happens on its own but it is sometimes it can happen because of inherited conditions like inability to acidify urine and cystinuria

usually tubular dysfunction is secondary to other conditions in the kidney for example nephrotic drugs or acute kidney injury

50
Q

acute tubular necrosis

A

Sudden death of the cells that line the tubules these cells are sensitive to low oxygen so therefore are damaged by ischaemia and toxins

51
Q

what happens with tubular dysfunction

A

inability to produce concentrated urine

52
Q

what does the anti-diuretic hormone do in tubular function

A

influences water balance which is essential for reabsorption of water making the urine more concentrated up

53
Q

how can tubular function be assessed in terms of osmolality

A

measure urine concentration by osmolality and compare with plasma osmolality

54
Q

what is the definition of urine osmolality

A

urine osmolality is directly proportional to osmotic work done by the kidney therefore is a correct measure of concentrating power

urine specific gravity (dipstick) usually proportional to osmolality but gives higher result if there is glycosuria or proteinuria

55
Q

what is normal urine: plasma ratio and what does it mean when ratio is equal to or less than 1

A

3:1

if ratio is less than 1 it means renal tubules not reabsorbing water

56
Q

what is a fluid deprivation test

A

used in attempt to find cause of excessive polyuria

57
Q
A

blood science (4 decks)

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