Lab 5: Biochemistry in renal disase (1) Flashcards Preview

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Flashcards in Lab 5: Biochemistry in renal disase (1) Deck (40)
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1
Q

Consequences of renal disease (4)

A
  • retention of waste products
  • disorders in red cell production and vitamin D
  • disorders in water balance/alterations in urine output
  • disorders in electrolyte balance
2
Q

What would presentation of renal disease depend on?

A
  • cause
  • glomerular/tubular dysfunction
  • number of affected nephrons
3
Q

What would the renal disease that affects glomerulus present with?

A

Glomerular renal disease:

A. Reduced filtration

  • reduced urine volume (oliguria/anuria)
  • increased plasma creatinine/urea
  • hyperkalaemia
  • hyperphosphataemia
  • metabolic acidosis

B. Damage to golomerular membrane:

  • proteinuria - large proteins
  • haematuria
4
Q

What would renal disease that affects tubules present with?

A

Tubular renal disease = reduced reabsorption:

  • polyuria, low urine osmolarity -> kidney not able to reabsorb water
  • metabolic acidosis -> kidney not able to reabsorb carbohydrate
  • proteinuria -> molecules not being reabsorbed
  • glycosuria
5
Q

Hormonal changes related to late renal disease

A
  • anaemia - due to decreased RBCs production
  • hypocalcaemia - lack of active vitamin D (so reduced Ca++ reabsorption)
6
Q

What’s uraemic syndrome ?

A

High level of waste product/ urea and creatinine

7
Q

Symptoms of the uremic syndrome

A
8
Q
A
9
Q

Tests for glomerular function - what do we look at (in relation to kidney function)?

A

Test for glomerular function

  • ability to remove waste products
  • integrity of glomerular membrane and ability to prevent large particles entering the filtrate
10
Q

Test for homronal function of the kidney - what do we look at (in terms of kidney function)?

A
  • vitamin D
  • erythropoietin
11
Q

Test for tubular function of the kidney. What do we look at, in terms of functional kidney ability?

A

Tubular function:

  • ability to adjust Na+/ K+, H+, water composition of a filtrate
  • reabsorb small proteins, amino acids, glucose
12
Q

What if GFR equivalent to?

A

GFR = clearance

Clearance = ability to remove waste products

13
Q

What’s the clearance?

A

Clearance = ability to remove waste products

The volume of plasma that is filtered by the kidneys, and from which the substance is completely cleared per unit time

14
Q

What are the criteria for an ideal marker for clearance = GFR?

A

No marker fulfils all these criteria

15
Q

Formula for the clearance

A
16
Q

Exogenous that can be used for assessment of GFR

A

Bolus injection - we time how long does it take to be cleared from the plasma

IV infusion -> and then we do clearance calculation

17
Q

Urea use in the assessment of GFR

pros and cons

A
18
Q

Creatinine use in assessment of GFR

pros and cons

A
19
Q

Cystatin C as a marker used for GFR assessment

pros and cons

A

Cystatin C is not routinely used in GFR assessment

20
Q

What’s needed to perform calculated GFR?

A

Clearance - blood and urine samples

(accurate 24 hour urine collection is needed)

21
Q

How to collect 24 hr urine?

A

Day 1

  • 8 am empty bladder (discard output)
  • commence 24 hr urine collection

(all urine passed from now until 8 am next day must be collected in the container)

Day 2

  • 8 am -> collect final urine output into the container
  • collect blood sample with 24 hr period
22
Q

Estimated (eGFR) vs calculated (GFR)

A
  • Estimated - no need to do 24 hr urine collection (concentration of the plasma used as a marker)
  • Calculated - 24 hr urine collection is needed
23
Q

Formula used for calculations of eGFR

in adults

A

(although there are many other formulas that can be used)

24
Q

Formula used for calculations of eGFR

in paediatrics

A
25
Q

Tests/ Ix used for assessment of tubular function: the ability to excrete/retain water

A
  • urine sodium, osmolarity and volume

compare with: serum sodium and osmolarity

26
Q

Tests/ Ix used for assessment of tubular function: the ability to maintain acid-balance

A
  • urine
  • blood pH
  • anion gap
  • sodium bicarbonate
27
Q

How to assess kidney ability to maintain electrolyte balance?

A
  • serum sodium and potassium
  • random urine sodium and potasium
28
Q

How to assess kidney ability to reabsorb small proteins, amino acids and glucose?

A
  • tubular proteinuria (different proteins/molecules)
  • serum and urine amino acids
  • urine glucose
29
Q

Up to what glucose level would the glucose be reabsorbed by the kidney?

A

urine glucose -> renal threshold of 11 mmol/L

30
Q

What do we measure (Ix) to check for the kidney ability to produce active vitamin D?

A
  • serum adjusted calcium
  • PTH

*if not enough vitamin D -> serum calcium will be low and PTH high (to keep calcium within normal range)

31
Q

What do we measure (Ix) to check for the kidney ability to secrete erythropoietin?

A
  • FBC -> look if there is any anaemia
  • EPO
32
Q

What criteria are there for a diagnosis of AKI?

A
33
Q

Examples of pre-renal causes of AKI

A
34
Q

Examples of intrinsic causes of AKI

A
35
Q

Examples of post-renal causes of AKI

A
36
Q

What (4) biochemical abnormalities does AKI present with?

A
  • increased urea/creatinine
  • hyponatraemia
  • hyperkalaemia
  • metabolic acidosis
37
Q

Why hyperkalaemia is more dangerous in AKI than CKD?

A

A patient is used to high levels of potassium in CKD, whereas in AKI hyperkalaemia is rapid - body does not have time to get used to

38
Q

What blood investigations do we do in AKI? (to identify the cause)

A

It’s more important to quickly identify a cause in AKI , so we can treat it quickly and prevent the progression of renal damage

39
Q

What ‘imaging’ we do as Ix in cause of AKI?

A

It’s more important to quickly identify a cause in AKI , so we can treat it quickly and prevent the progression of renal damage

40
Q

How to determine if it is pre-renal or intrinsic kidney injury?

A

Look at urea and creatinine

In pre- renal -> much higher increase in serum urea/creatinine

(because some urea is reabsorbed through tubule cells - so blood flow is slowed down, filter goes longer through the nephrone - more urea is reabsorbed)

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